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.Digestion is the mechanical and chemical breaking down of food into smaller components that can be absorbed into a blood stream, for instance.^ Digestion (mechanical and chemical processes {hydrolysis} break down ingested food into small molecules) .
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ Chemical digestion is the breaking down of large molecules which cannot be absorbed, into smaller pieces which can be taken into the body.

^ Digestion is the mechanical and chemical process of breaking down food into smaller compounds.
  • Digestion 19 January 2010 18:50 UTC digestion.ygoy.com [Source type: FILTERED WITH BAYES]

.Digestion is a form of catabolism: a break-down of larger food molecules to smaller ones.^ Digestion is the mechanical and chemical process of breaking down food into smaller compounds.
  • Digestion 19 January 2010 18:50 UTC digestion.ygoy.com [Source type: FILTERED WITH BAYES]

^ Food digestion is like metabolism i.e., breaking down food into small molecules.
  • Digestion 19 January 2010 18:50 UTC digestion.ygoy.com [Source type: FILTERED WITH BAYES]

^ Mechanical digestion breaks down food into smaller compounds as smaller compounds are easily absorbed.
  • Digestion 19 January 2010 18:50 UTC digestion.ygoy.com [Source type: FILTERED WITH BAYES]

.In mammals, food enters the mouth, being chewed by teeth, with chemical processing beginning with chemicals in the saliva from the salivary glands.^ Mechanical breakdown begins in the mouth by chewing (teeth) and actions of the tongue.

^ Digestion begins in the mouth with the chewing of food (mastication).
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Saliva moistens food particles, and begins the chemical digestion of carbohydrates.

.Then it travels down the esophagus into the stomach, where acid both kills most contaminating microorganisms and begins mechanical break down of some food (e.g., denaturation of protein), and chemical alteration of some.^ Digestion is the mechanical and chemical process of breaking down food into smaller compounds.
  • Digestion 19 January 2010 18:50 UTC digestion.ygoy.com [Source type: FILTERED WITH BAYES]

^ Mechanical digestion breaks down food into smaller compounds as smaller compounds are easily absorbed.
  • Digestion 19 January 2010 18:50 UTC digestion.ygoy.com [Source type: FILTERED WITH BAYES]

^ This wave forces food into the esophagus.

.After some time (typically an hour or two in humans, 4-6 hours in dogs, somewhat shorter duration in house cats, ...^ About two months ago, I ordered one of your PetAlive remedies for my cat and I then fell upon your human line of holistic remedies.
  • Maintain Normal Stomach Acid Levels & Healthy Digestive Systems Naturally 19 January 2010 18:50 UTC www.nativeremedies.com [Source type: FILTERED WITH BAYES]
  • Maintain Normal Stomach Acid Levels & Healthy Digestive Systems Naturally 19 January 2010 18:50 UTC www.enaturalremedies.com [Source type: FILTERED WITH BAYES]

^ This design handles one to two percent solids, and uses a shorter retention time, as short as two to six days.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

), the results go through the .small intestine, through the large intestine, and are excreted during defecation.^ Although 90% of all water absorption occurs in the small intestine, the large intestine absorbs enough to make it an important organ in maintaining the bodys water balance.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ Several specialized compartments occur along this length: mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.

^ The whole process of digestion involves many different organs, which are called the digestive system, and include the mouth, esophagus, stomach, small intestines, large intestines, rectum and anus.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

[1]
.Other organisms use different mechanisms to digest food.^ The pancreas uses other mechanisms for protection.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Digestion (mechanical and chemical processes {hydrolysis} break down ingested food into small molecules) .
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ This good bacteria helps in breaking down the starches of plant and other foods that human body finds difficult to digest.
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Contents

Digestive systems

.Digestive systems take many forms.^ Your digestive system is smart; it knows how to distinguish between foods that will take a while and foods that won’t.
  • Digestion | Crazy Sexy Life 19 January 2010 18:50 UTC crazysexylife.com [Source type: General]

^ The whole process of digestion involves many different organs, which are called the digestive system, and include the mouth, esophagus, stomach, small intestines, large intestines, rectum and anus.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ The Digestive System Page This page takes a very long time to download a large number of impressive photographs of the system.

A fundamental distinction is between internal and external digestion. External digestion was the first to evolve, and most fungi still rely on it.[2] .In this process, enzymes are secreted into the environment surrounding the organism, where they break down an organic material, and some of the products diffuse back to the organism.^ The enzymes help break down fats, proteins, and carbohydrates.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Digestion (mechanical and chemical processes {hydrolysis} break down ingested food into small molecules) .
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ In this chapter we will be concerned primarily with the mechanisms involved in breaking down the foodstuffs so that they can be absorbed.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

.Later, animals evolved by rolling into a tube and acquiring internal digestion, which is more efficient because more of the breakdown products can be captured, and the chemical environment can be more efficiently controlled.^ It processes your food so well that you want less because your body is more efficiently breaking down what you eat and therefore getting more of the nutrition from the food you are eating.
  • Optimal Digestion 19 January 2010 18:50 UTC www.breathing.com [Source type: FILTERED WITH BAYES]

^ Dead tissues contain enzymes which begin the chemical breakdown of their proteins; hanging meat, in a sense, begins the digestive process before the meat is even delivered to the food market.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

^ Because anaerobic digesters are expensive to install and manage, the above considerations and many others should be researched and then factored into an economic-feasibility assessment.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

[3]
.Some organisms, including nearly all spiders, simply secrete biotoxins and digestive chemicals (eg, [enzymes]) into the extracellular environment prior to ingestion of the consequent "soup". In others, once potential nutrients or food is inside the organism, digestion can be conducted to a vesicle or a sac-like structure, through a tube, or through several specialized organs aimed at making the absorption of nutrients more efficient.^ Eight digestive enzymes are responsible for chemical digestion.
  • Digestion 19 January 2010 18:50 UTC digestion.ygoy.com [Source type: FILTERED WITH BAYES]

^ Some animals use intracellular digestion , where food is taken into cells by phagocytosis with digestive enzymes being secreted into the phagocytic vesicles .

^ The liver is the clearinghouse for all nutrient absorption through the gastrointestinal system.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

Secretion systems

.Bacteria use several systems to obtain nutrients from other organisms in the environment.^ Due to its acidic environment, the stomach is also a decontamination chamber for bacteria and other potentially toxic microorganisms that may have entered your gastrointestinal system through your mouth.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Extracellular digestion occurs in the lumen (or opening) of a digestive system, with the nutrient molecules being transferred to the blood or some other body fluid.

^ The digestive system uses mechanical and chemical methods to break food down into nutrient molecules that can be absorbed into the blood.

Channel transport system

.In a channel transport system several proteins form a contiguous channel traversing the inner and outer membranes of the bacteria.^ After denaturation in the stomach, the long single-chain protein is transported to the proximal small intestine, the duodenum, which contains several types of proteases.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

It is a simple system, which consists of only three protein subunits: the ABC protein, membrane fusion protein (MFP), and outer membrane protein (OMP). .This secretion system transports various molecules, from ions, drugs, to proteins of various sizes (20 - 900 kDa).^ It has a detoxification system, in which drugs and toxins are chemically converted to molecules that can be eliminated through the kidneys (urine) or the intestine (stool).
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ The cost of an anaerobic-digestion system can vary dramatically depending on its size, intended purposes, and sophistication.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

.The molecules secreted vary in size from the small Escherichia coli peptide colicin V, (10 kDa) to the Pseudomonas fluorescens cell adhesion protein LapA of 900 kDa.^ The only proteolytic (protein-digesting) enzyme in the stomach is pepsin, which is secreted by chief cells.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ When chyme containing fatty acids and glucose enters the small intestine, it triggers enteroendocrine cells of the intestine to secrete two hormones: .

^ Carbohydrates are a varied combination of both very small and very large molecules and comprise about 40 to 45 percent of the energy supply for your body.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

[4]

Molecular syringe

A molecular syringe is used through which a bacterium (e.g. certain types of .Salmonella, Shigella, Yersinia) can inject proteins into eukaryotic cells.^ When these cells die, their hemoglobin is broken up into heme and the protein carrier.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

^ Protein carriers or channels hook-up to these nutrients and take them through the cell wall of the jejunum and into the portal vein, which carries them to the liver.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

.One such mechanism was first discovered in Y. pestis and showed that toxins could be injected directly from the bacterial cytoplasm into the cytoplasm of its host's cells rather than simply be secreted into the extracellular medium.^ Even though parietal cells secrete hydrogen ions (H+) and chloride ions (Cl-) separately into the stomach lumen, the net effect is secretion of hydrochloric acid (HCl).
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ Success was higher when the prey moved directly away, rather than towards the owls (50% and 18%, respectively).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Among these cells are enteroendocrine cells, which secrete hormones into the blood stream.

[5]

Conjugation machinery

Schematic drawing of bacterial conjugation. Conjugation diagram 1- Donor cell produces pilus. 2- Pilus attaches to recipient cell, brings the two cells together. 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell. 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili; both cells are now viable donors.
The conjugation machinery of some bacteria (and archaeal flagella) is capable of transporting both DNA and proteins. .It was discovered in Agrobacterium tumefaciens, which uses this system to introduce the Ti plasmid and proteins into the host which develops the crown gall (tumor).^ The digestive system uses mechanical and chemical methods to break food down into nutrient molecules that can be absorbed into the blood.

[6]. The VirB complex of Agrobacterium tumefaciens is the prototypic system.[7]
The nitrogen fixing Rhizobia are an interesting case, wherein conjugative elements naturally engage in inter-kingdom conjugation. Such elements as the Agrobacterium Ti or Ri plasmids contain elements that can transfer to plant cells. .Transferred genes enter the plant cell nucleus and effectively transform the plant cells into factories for the production of opines, which the bacteria use as carbon and energy sources.^ The small intestinal tract cells also require energy to maintain integrity of the cell wall, and production of energy requires healthy levels of vitamin B5.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Plants store their energy by stringing together many glucose molecules into a long complex of several hundred to several thousand glucose molecules.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Inside the cell they are broken into amino acids that then enter the capillary.

Infected plant cells form crown gall or root tumors. The Ti and Ri plasmids are thus endosymbionts of the bacteria, which are in turn endosymbionts (or parasites) of the infected plant.
The Ti and Ri plasmids are themselves conjugative. Ti and Ri transfer between bacteria uses an independent system (the tra, or transfer, operon) from that for inter-kingdom transfer (the vir, or virulence, operon). Such transfer creates virulent strains from previously avirulent Agrobacteria.

Release of outer membrane vesicles

.In addition to the use of the multiprotein complexes listed above, Gram-negative bacteria possess another method for release of material: the formation of outer membrane vesicles.^ In some cases the liver holds the absorbed materials, converting them to another form, and releases them slowly.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

[8] .Portions of the outer membrane pinch off, forming spherical structures made of a lipid bilayer enclosing periplasmic materials.^ The palate forms the roof of the oral cavity and is made up of a hard anterior portion and a soft posterior portion.

.Vesicles from a number of bacterial species have been found to contain virulence factors, some have immunomodulatory effects, and some can directly adhere to and intoxicate host cells.^ Histology The lobes of the liver are made up of lobules that contain specialized epithelial cells called hepatocytes (liver cells),arranged in plates around a central vein.

^ One special kind of starch is found in some foods, such as raw, green bananas.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Some chemicals in food (caffeine) may directly stimulate G cells.

While release of vesicles has been demonstrated as a general response to stress conditions, the process of loading cargo proteins seems to be selective.[9]

Phagosome

A phagosome is a vacuole formed around a particle absorbed by phagocytosis. .The vacuole is formed by the fusion of the cell membrane around the particle.^ By providing the membrane around all your cells, fats are vital for insulating your body from the outside world.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

.A phagosome is a cellular compartment in which pathogenic microorganisms can be killed and digested.^ Thermophilic digestion kills more pathogenic bacteria, but it has higher costs due to maintaining higher temperatures, and thermophilic digesters may be less stable.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

Phagosomes fuse with lysosomes in their maturation process, forming phagolysosomes. .In humans, Entamoeba histolytica can phagocytose red blood cells.^ The phagocytosis of aged red blood cells liberates iron, globin, and bilirubin (derived from heme).
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ Phagocytosis: The Kupffer's cells phagocytize worn-out red and white blood cells, and also some bacteria.

^ Bile contains some of the materials of red blood cells which have come to the end of their life span, about 120 days.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

[10]
Trophozoites of Entamoeba histolytica with ingested erythrocytes

Gastrovascular cavity

.The gastrovascular cavity functions as a stomach in both digestion and the distribution of nutrients to all parts of the body.^ What is the primary digestive function of the stomach?
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ Primary function of stomach is to receive food, mix it with gastric juice, begin digestion of proteins, and move food to the small intestine.

^ Part of the digestion process, then, is the selective transport of nutrients through the cell wall that lines your intestinal tract.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

.Extracellular digestion takes place within this central cavity which is lined with the gastrodermis, the internal layer of epithelium.^ The mucosa contains many cavities lined with glandular epithelium.

^ The stomach secretions do, in fact, digest the lining layer and proceed to the muscular layer, producing the ulcer "crater".
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

^ The most important part of digestion takes place in the small intestine , where most chemical digestion and absorption of food occurs.
  • Maintain Normal Stomach Acid Levels & Healthy Digestive Systems Naturally 19 January 2010 18:50 UTC www.nativeremedies.com [Source type: FILTERED WITH BAYES]

.This cavity has only one opening to the outside that functions as both a mouth and an anus: waste and undigested matter is excreted through the mouth/anus, which can be described as an incomplete gut.^ The mouth opens into the oropharynx through the fauces.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ The small intestine begins at the pyloric sphincter of the stomach, coils through the central and inferior part of the abdominal cavity, and eventually opens into the large intestine.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ As the beak opens and closes, each movement propels the water droplet one step closer to the bird's mouth.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

Aboral end
Oral end
Mouth
Oral end
Aboral end
    Exoderm
    Gastroderm
    Mesoglea
    Digestive cavity
Medusa (left) and polyp (right)[11]
.In a plant such as the Venus Flytrap that can make its own food through photosynthesis, it does not eat and digest its prey for the traditional objectives of harvesting energy and carbon, but mines prey primarily for essential nutrients (nitrogen and phosphorus in particular) that are in short supply in its boggy, acidic habitat.^ At various times and under various conditions, ceca are the site for (1) fermentation and further digestion of food (especially for the breakdown of cellulose) and absorption of nutrients, (2) production of antibodies, and (3) the use and absorption of water and nitrogenous components (Clench 1999).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Most foods you eat are a mixture of all of these different molecules, and since you need a variety of types of nutrients, your body must be able to digest these varied types of molecules in food.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ When you eat foods with starch, like corn or potatoes, your body digests this very large carbohydrate in much the same way as it digests protein.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

[12]
Venus Flytrap (Dionaea muscipula) leaf

Specialized organs and behaviors

Catalina Macaw exhibits its seed shearing beak.
Squid beak and ruler for size comparison.
Teeth of a Carcharodon megalodon.
Rough illustration of a ruminant digestive system.
.To aid in the digestion of their food animals evolved organs such as beaks, tongues, teeth, a crop, gizzard, and others.^ Although we might not think of it as such, the stomach is a muscular organ that contracts and expands in order to mix the food with digestive juices.
  • Maintain Normal Stomach Acid Levels & Healthy Digestive Systems Naturally 19 January 2010 18:50 UTC www.nativeremedies.com [Source type: FILTERED WITH BAYES]

^ A Price Worth Paying -- Birds don't need teeth to grind their food; they solve the mashing problem with a powerful gizzard.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Complex carbohydrates that resist the enzyme degradation, such as fiber and resistant starch, remain, as do a small amount of other food molecules and nutrients that have escaped the digestion process.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

Beaks

.Macaws primarily eat seeds, nuts, and fruit, using their impressive beaks to open even the toughest seed.^ Hawfinches are seed-eaters & use their bills to crack open large, hard seeds .
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Macaws use their strong hook-like bills to feed on nuts.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.First they scratch a thin line with the sharp point of the beak, then they shear the seed open with the sides of the beak.^ It wasn't clear how they could catch them; birds that hunt flying insects usually have short beaks to help them open their mouths wide.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

The mouth of the squid is equipped with a sharp horny beak mainly made of chitin[13] and cross-linked proteins. .It is used to kill and tear prey into manageable pieces.^ Typically, raptor prey are killed by the talons of the contracting foot being driven into their bodies; if required, the hooked bill is used to kill prey being held by the talons (check this short video of an owl trying to eat a moth ).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Eagles (and hawks ) are diurnal raptors & use their hook-like bills to tear apart large prey.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.The beak is very robust, but does not contain any minerals, unlike the teeth and jaws of many other organisms, including marine species.^ Weight has been minimized by the loss of teeth &, in many birds, limited jaw musculature.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

[14] The beak is the only indigestible part of the squid.

Tongue

.The tongue is skeletal muscle on the floor of the mouth that manipulates food for chewing (mastication) and swallowing (deglutition).^ Digestion begins in the mouth with the chewing of food (mastication).
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Swallowed food passes from the mouth into the oropharynx and laryngopharynx, the muscular contractions of which help propel food into the esophagus and then into the stomach and then to the pyloric valve.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ Mucus lubricates the food so it can easily be moved about in the mouth, formed into a ball, and swallowed.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

It is sensitive and kept moist by saliva. .The underside of the tongue is covered with a smooth mucous membrane.^ It is composed of skeletal muscle covered with mucous membrane.

.The tongue is utilised to roll food molecules into a bolus before being transported down the esophagus through the use of peristalsis.^ It passes a bolus into the stomach by peristalsis.

^ This wave forces food into the esophagus.

^ Your body uses a number of enzymes to cut down a large, linear starch chain into the small individual units that are linked together, the glucose molecules, which can then be absorbed in the intestines.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

The sublingual region underneath the front of the tongue is a location where the oral mucosa is very thin, and underlain by a plexus of veins. This is an ideal location for introducing certain medications to the body. .The sublingual route takes advantage of the highly vascular quality of the oral cavity, and allows for the speedy application of medication into the cardiovascular system, bypassing the gastrointestinal tract.^ The organs that collectively perform digestion and absorption compose the digestive system and are usually divided into two main groups: those composing the gastrointestinal (GI) tract or alimentary canal and accessory structures.

^ The major portion of saliva is secreted by the salivary glands, which lie outside the mouth and pour their contents into ducts that empty into the oral cavity.

^ A salivary gland is any cell or organ that releases a secretion called saliva into the oral cavity.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

Teeth

.Teeth (singular, tooth) are small whitish structures found in the jaws (or mouths) of many vertebrates that are used to tear, scrape, milk and chew food.^ Weight has been minimized by the loss of teeth &, in many birds, limited jaw musculature.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ The whole process of digestion involves many different organs, which are called the digestive system, and include the mouth, esophagus, stomach, small intestines, large intestines, rectum and anus.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ Digestion begins in the mouth with the chewing of food (mastication).
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

Teeth are not made of bone, but rather of tissues of varying density and hardness. The shape of an animal's teeth is related to its diet. .For example, plant matter is hard to digest, so herbivores have many molars for chewing.^ The mouth is formed by the cheeks, hard and soft palates, lips, and tongue, which aid mechanical digestion in the process of mastication (chewing food and mixing it with saliva).

The teeth of carnivores are shaped to kill and tear meat, using specially-shaped canine teeth. .Herbivores' teeth are made for grinding food materials, in this case, plant parts.^ A Price Worth Paying -- Birds don't need teeth to grind their food; they solve the mashing problem with a powerful gizzard.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Normal teeth, shown in Figure 284 , are covered with an extremely hard material (enamel), which can cut most foods and grind others.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

^ Feces , the material eventually eliminated from the bowel, is made up in part of indigestible food residues, the normal bacteria of the colon, and, to a very large extent, water.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

Crop

.A crop, or croup, is a thin-walled expanded portion of the alimentary tract used for the storage of food prior to digestion.^ So if your digestion is slow or weak, a good dash of hot sauce in your food will prove useful.
  • digestion « FOX News Health Blog « FOXNews.com 19 January 2010 18:50 UTC health.blogs.foxnews.com [Source type: General]

^ The movement of the food, or chyme, through the digestive tract is very important.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ The intestinal brush border (the absorptive surface of the small intestine) can be negatively affected by food allergies, which cause inflammation along the intestinal tract wall.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

In some birds it is an expanded, muscular pouch near the gullet or throat. .In adult doves and pigeons, the crop can produce crop milk to feed newly hatched birds.^ Crop 'milk' is rich in proteins, fats, & vitamins and is produced by proliferation & sloughing off of epithelial cells that line the crop.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

[15]
Certain insects may have a crop or enlarged oesophagus.

Abomasum

Herbivores have evolved cecums (or an abomasum in the case of ruminants). Ruminants have a fore-stomach with four chambers. These are the rumen, reticulum, omasum, and abomasum. .In the first two chambers, the rumen and the reticulum, the food is mixed with saliva and separates into layers of solid and liquid material.^ Chewing the food cuts and grinds it while mixing it with saliva.
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^ It delivers the saliva-mixed food from the mouth to the stomach and serves as an air lock between the outside world and the digestive tract.
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^ Anaerobic digestion works in a two-stage process to decompose organic material (i.e., volatile solids) in the absence of oxygen.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

Solids clump together to form the cud (or bolus). .The cud is then regurgitated, chewed slowly to completely mix it with saliva and to break down the particle size.^ Chewing the food cuts and grinds it while mixing it with saliva.
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.Fiber, especially cellulose and hemi-cellulose, is primarily broken down into the volatile fatty acids, acetic acid, propionic acid and butyric acid in these chambers (the reticulo-rumen) by microbes: (bacteria, protozoa, and fungi).^ In the first stage, the volatile solids in manure are converted into fatty acids by anaerobic bacteria known as “acid formers.” In the second stage, these acids are further converted into biogas by more specialized bacteria known as “methane formers.” With proper planning and design, this anaerobic-digestion process, which has been at work in nature for millions of years, can be managed to convert a farm’s waste-stream into an asset.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

^ The food that makes it into the large intestine is primarily fiber, and the large intestine contains an ecosystem of bacteria that can ferment much of this fiber, producing many nutrients necessary for the health of the colon cells.
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^ By fermenting the fiber your body couldn't directly digest, these healthy colonic bacteria also produce short-chain fatty acids that the cells of the colon use for their own nourishment.
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.In the omasum water and many of the inorganic mineral elements are absorbed into the blood stream.^ Thus, all of the products of digestion which enter the blood stream are brought into close contact with the cells of the liver before being passed on to the heart.
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The abomasum is the fourth and final stomach compartment in ruminants. .It is a close equivalent of a monogastric stomach (eg, those in humans or pigs), and digesta is processed here in much the same way.^ When you eat foods with starch, like corn or potatoes, your body digests this very large carbohydrate in much the same way as it digests protein.
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^ In duodenal ulcers, gastric juice entering the duodenum may digest a portion of the duodenal lining; the consequences are in many ways the same as those in gastric ulcer.
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.It serves primarily as a site for acid hydrolysis of microbial and dietary protein, preparing these protein sources for further digestion and absorption in the small intestine.^ The structure of the mucosa of the small intestine favors absorption of digested materials.
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^ At various times and under various conditions, ceca are the site for (1) fermentation and further digestion of food (especially for the breakdown of cellulose) and absorption of nutrients, (2) production of antibodies, and (3) the use and absorption of water and nitrogenous components (Clench 1999).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Digestion in the Duodenum, the Liver, and Pancreas :      The duodenum, the first portion of the small intestine, plays a special part in the digestive process.
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.Digesta is finally moved into the small intestine, where the digestion and absorption of nutrients occurs.^ The structure of the mucosa of the small intestine favors absorption of digested materials.
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^ What little digestible material remains in the small intestine is digested and reabsorbed in the large intestine.
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^ The attachments of the small intestine are so loose that almost any type of motion can occur.
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.Microbes produced in the reticulo-rumen are also digested in the small intestine.^ What little digestible material remains in the small intestine is digested and reabsorbed in the large intestine.
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^ The structure of the mucosa of the small intestine favors absorption of digested materials.
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^ The majority of starch is also digested in the duodenum and jejunum, the first and second segments of the small intestine.
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Specialized behaviors

A flesh fly "blowing a bubble". One explanation of this behaviour is that the fly regurgitates its food into a bubble in order to increase the concentration of its food by evaporating excessive water content
.Regurgitation has been mentioned above under abomasum and crop, referring to crop milk, a secretion from the lining of the crop of pigeons and doves with which the parents feed their young by regurgitation.^ Crop 'milk' is rich in proteins, fats, & vitamins and is produced by proliferation & sloughing off of epithelial cells that line the crop.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

[16].
.Many sharks have the ability to turn their stomachs inside out and evert it out of their mouths in order to get rid of unwanted contents (perhaps developed as a way to reduce exposure to toxins).^ The importance of the esophagus' ability to separate the mouth and stomach can be seen in the condition known as GERD (gastroesophageal reflux disease), in which the esophageal barrier is not effective, so the acid contents of the stomach can escape into the esophagus.
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.Other animals, such as rabbits and rodents, practice coprophagia behaviors - eating specialized feces in order to re-digest food, especially in the case of roughage.^ When you eat foods with starch, like corn or potatoes, your body digests this very large carbohydrate in much the same way as it digests protein.
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^ Red-tailed Hawks subsist primarily on rodents and larger mammals such as skunks and rabbits.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Complex carbohydrates that resist the enzyme degradation, such as fiber and resistant starch, remain, as do a small amount of other food molecules and nutrients that have escaped the digestion process.
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.Capybara, rabbits, hamsters and other related species do not have a complex digestive system as do, for example, ruminants.^ Complex carbohydrates that resist the enzyme degradation, such as fiber and resistant starch, remain, as do a small amount of other food molecules and nutrients that have escaped the digestion process.
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^ Cogeneration Power Sources Access to 11 articles discussing engines and other technologies used with a methane-digester system to generate power.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

^ Contains news and media articles on digester systems from BioCycle, Agri News, and other resources.
  • Anaerobic Digestion of Animal Wastes: Factors to Consider 19 January 2010 18:50 UTC www.attra.org [Source type: Academic]

.Instead they extract more nutrition from grass by giving their food a second pass through the gut.^ Their kidneys extract nitrogenous wastes from the bloodstream, but instead of excreting it as urea dissolved in urine as we do, they excrete it in the form of uric acid.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.Soft fecal pellets of partially digested food are excreted and generally consumed immediately.^ With a change in diet from medium-small mussels (Mytilus edulis) to a diet of soft food pellets, gizzard mass was reduced by almost 50% in about 8 days.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ A switch back to a soft food pellet diet caused a further decline in gizzard mass.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

They also produce normal droppings, which are not eaten.
.Young elephants, pandas, koalas, and hippos eat the feces of their mother, probably to obtain the bacteria required to properly digest vegetation.^ Digestive enzyme support can also be obtained from fresh pineapple or papaya, which contain the enzyme bromelain, and other fresh vegetables and herbs.
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.When they are born, their intestines do not contain these bacteria (they are completely sterile).^ They can be remedied by restoring the normal intestinal bacteria.
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^ Along with these movements, the small intestine secretes from its lining innumerable digestive enzymes which complete the disintegration and dissolution of its contents.
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.Without them, they would be unable to get any nutritional value from many plant components.^ The remainder consists of insoluble and indigestible materials and has no nutritional value to animals, though it makes very good fertilizer for some plants.
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In earthworms

.An earthworm's digestive system consists of a mouth, pharynx, esophagus, crop, gizzard, and intestine.^ The 'canal' includes the oral cavity, pharynx, esophagus (which includes a crop in some birds), stomach (proventriculus & gizzard), small intestine, & large intestine.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

The mouth is surrounded by strong lips which act like a hand to grab pieces of dead grass, leaves, and weeds, with bits of soil to help chew. .The lips break the food down into smaller pieces.^ Bile emulsifies fats (or, in other words, breaks fats down into tiny particles).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Before proceeding with this discussion, it may be helpful to identify the major foods and their components as well as the enzymes which break them down.
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^ Sometimes a piece of food which is large is taken into the esophagus.
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.In the pharynx the food is lubricated by mucus secretions for easier passage.^ Proventriculus - also called the glandular stomach; receives food from the esophagus & secretes mucus, HCl, and pepsinogen.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.The esophagus adds calcium carbonate to neutralize the acids formed by food matter decay.^ Stoichimetrically, a material containing 1% S will require 31.25 metric tons of calcium carbonate to neutralize the acid produced by 1000 metric tons of the material.

^ Add the specified amount and strength of acid based on the carbonate rating.

Temporary storage occurs in the crop where food and calcium carbonate are mixed. The powerful muscles of the gizzard churn and mix the mass of food and dirt. .When the churning is complete, the glands in the walls of the gizzard add enzymes to the thick paste which aid in the chemical breakdown of the organic matter.^ Dead tissues contain enzymes which begin the chemical breakdown of their proteins; hanging meat, in a sense, begins the digestive process before the meat is even delivered to the food market.
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^ Digestive enzymes, which are organic catalysts, accelerate food breakdown and are usually named after the substance broken down.
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^ These enzymes, mixed with the slurry of material leaving the stomach, continue the chemical breakdown of the principal foodstuffs.
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.By peristalsis the mixture is sent to the intestine where friendly bacteria continue chemical breakdown.^ These enzymes, mixed with the slurry of material leaving the stomach, continue the chemical breakdown of the principal foodstuffs.
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^ Cooking foods at home continues the process of breakdown, both mechanically and chemically.
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.This releases carbohydrates, protein, fat, and various vitamins and minerals for absorption into the body.^ It produces and secretes many of the enzymes necessary for digestion, which include the enzymes that digest protein (trypsin, chymotryosin, carboxypeptidase, and elastase), enzymes that digest fat (lipase and phospholipase), and the enzyme that digests carbohydrate (alpha-amylase).
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^ When you eat foods with starch, like corn or potatoes, your body digests this very large carbohydrate in much the same way as it digests protein.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

^ The fat-soluble vitamins (vitamins A, D, K, and E), as discussed above, are absorbed with fat miscelles, and therefore require fat to be present for their full absorption.
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Overview of vertebrate digestion

.In most vertebrates, digestion is a multi-stage process in the digestive system, starting from ingestion of raw materials, most often other organisms.^ In order to make these estimates, a multi-stage methodology was employed that is often taught in courses on international strategic planning at graduate schools of busines ...
  • digestion - Lulu.com 19 January 2010 18:50 UTC www.lulu.com [Source type: General]

^ Normal teeth, shown in Figure 284 , are covered with an extremely hard material (enamel), which can cut most foods and grind others.
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^ In order to make these estimates, a multi-stage methodology was employed that is often taught in courses on international strategic planning at graduate schools of business ...
  • digestion - Lulu.com 19 January 2010 18:50 UTC www.lulu.com [Source type: General]

.Ingestion usually involves some type of mechanical and chemical processing.^ In the digestive process, these foods are broken down mechanically and chemically until the breakdown products are small enough so that they can be absorbed.
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^ Cooking foods at home continues the process of breakdown, both mechanically and chemically.
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Digestion is separated into four steps:
  1. Ingestion: placing food into the mouth (entry of food in the digestive system),
  2. Mechanical and chemical breakdown: mastication and the mixing of the resulting bolus with water, acids, bile and enzymes in the stomach and intestine to break down complex molecules into simple structures,
  3. Absorption: of nutrients from the digestive system to the circulatory and lymphatic capillaries through osmosis, active transport, and diffusion, and
  4. Egestion (Excretion): Removal of undigested materials from the digestive tract through defecation.
Underlying the process is muscle movement throughout the system through swallowing and peristalsis. .Each step in digestion requires energy, and thus imposes an "overhead charge" on the energy made available from absorbed substances.^ For example, ground beef requires less mechanical breakdown in digestion than does the meat from which it is made.
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^ The monosaccharide products of carbohydrate digestion, glucose and galactose, are actively absorbed through the intestine by a process that requires energy.
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^ The Digestion of the Principal Foods Note : Substances in the top row must be broken down by enzymes in order to be absorbed, while substances in the lowest row can be absorbed without difficulty.
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Differences in that overhead cost are important influences on lifestyle, behavior, and even physical structures. Examples may be seen in humans, who differ considerably from other hominids (lack of hair, smaller jaws and musculature, different dentition, length of intestines, cooking, etc).
.The major part of digestion takes place in the small intestine.^ The ileum is the final part of the small intestine.
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^ Part of the digestion process, then, is the selective transport of nutrients through the cell wall that lines your intestinal tract.
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^ The majority of carbohydrate hydrolysis occurs in the small intestine; that is, these carbohydrates are mainly transported to the small intestine before they are cut into the monosaccharides glucose, galactose, and fructose.
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.The large intestine primarily serves as a site for fermentation of indigestible matter by gut bacteria and for resorption of water from digesta before excretion.^ The food that makes it into the large intestine is primarily fiber, and the large intestine contains an ecosystem of bacteria that can ferment much of this fiber, producing many nutrients necessary for the health of the colon cells.
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^ Fiber is called soluble or insoluble, depending on its ability to take up water and to be fermented in the large intestine.
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^ Fiber travels through your gastrointestinal tract intact and ends up in the large intestine, where it provides nutrition for the intestinal bacteria that ferment it.
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In mammals, preparation for digestion begins with the cephalic phase in which saliva is produced in the mouth and digestive enzymes are produced in the stomach. Mechanical and chemical digestion begin in the mouth where food is chewed, and mixed with saliva to begin enzymatic processing of starches. .The stomach continues to break food down mechanically and chemically through churning and mixing with both acids and enzymes.^ Once the food-acid-enzyme mixture leaves the stomach, it is called chyme.
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^ When the food enters the fundus and body of the stomach, the lining of the fundus (called the gastric fundal mucosa) produces hydrocholoric acid (HCl).
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^ After chewing, the food's next stop is the stomach, where an adequate amount of stomach acid (hydrochloric acid) is the next necessity.
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Absorption occurs in the stomach and gastrointestinal tract, and the process finishes with defecation.[1]

Human digestion process

Salivary glands Parotid gland Submandibular gland Sublingual gland Pharynx Tongue Esophagus Pancreas Pancreatic duct Stomach Ileum Anus Rectum Vermiform appendix Cecum Descending colon Ascending colon Transverse colon Bile duct Duodenum Gallbladder Liver Oral cavity
Upper and Lower human gastrointestinal tract
.The whole digestive system is around 9 meters long.^ The whole process of digestion involves many different organs, which are called the digestive system, and include the mouth, esophagus, stomach, small intestines, large intestines, rectum and anus.
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In a healthy human adult this process can take between 24 and 72 hours.

Phases of gastric secretion

.
  • Cephalic phase - This phase occurs before food enters the stomach and involves preparation of the body for eating and digestion.^ What is the cephalic phase of gastric digestion and what occurs?
    • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

    ^ Phases of human digestion Cephalic phase - This phase occurs before food enters the stomach and involves preparation of the body for eating and digestion.
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ Digestion is how our bodies absorb nutrients from the food we eat.
    • Digestion, digestion problems, colostrum 19 January 2010 18:50 UTC colostrum.lifetips.com [Source type: General]

    .Sight and thought stimulate the cerebral cortex.^ Sight and thought stimulate the cerebral cortex .
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ The thought, sight, smell, or taste of food causes the cerebral cortex and hypothalamus to send impulses to the medulla oblongata, which sends parasympathetic signals via the vagus nerve to the submucosal plexus.

    .Taste and smell stimulus is sent to the hypothalamus and medulla oblongata.^ Taste and smell stimulus is sent to the hypothalamus and medulla oblongata .
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ The cerebral cortex and the feeding center in the hypothalamus send nerve impulses to the medulla oblongata.
    • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

    After this it is routed through the vagus nerve and release of acetylcholine. Gastric secretion at this phase rises to 40% of maximum rate. .Acidity in the stomach is not buffered by food at this point and thus acts to inhibit parietal (secretes acid) and G cell (secretes gastrin) activity via D cell secretion of somatostatin.
  • Gastric phase - This phase takes 3 to 4 hours.^ Thus, this study demonstrates substantial adjustments of pH and gastric motility in incubating King Penguins, which may contribute to the inhibition of digestive gastric processes.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ Proventriculus - also called the glandular stomach; receives food from the esophagus & secretes mucus, HCl, and pepsinogen.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ In these large ceca, food particles are acted upon by cecal secretions, bacteria, and fungi and nutrients can be absorbed.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    It is stimulated by distention of the stomach, presence of food in stomach and decrease in pH. .Distention activates long and myentric reflexes.^ Distention activates long and myentric reflexes.
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ This phase is mediated by short and long reflexes and activates the secretion of gastrin.
    • Digestion and Absorption of Food - Biology Online 19 January 2010 18:50 UTC www.biology-online.org [Source type: Academic]

    This activates the release of acetylcholine which stimulates the release of more gastric juices. As protein enters the stomach, it binds to hydrogen ions, which lowers the pH of the stomach to around pH 1-3. Inhibition of gastrin and HCl secretion is lifted. .This triggers G cells to release gastrin, which in turn stimulates parietal cells to secrete HCl.^ The release of acetylcholine by the parasympathetic fibers stimulates the secretion of gastrin by the G cells.

    ^ What ionic compound do parietal cells secrete?
    • SLU Physiology lab - Digestion - Stark 19 January 2010 18:50 UTC starklab.slu.edu [Source type: Reference]

    ^ HCl release is also triggered by acetylcholine and histamine .
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    .HCl release is also triggered by acetylcholine and histamine.
  • Intestinal phase - This phase has 2 parts, the excitatory and the inhibitory.^ Intestinal phase - This phase has 2 parts, the excitatory and the inhibitory.
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ HCl release is also triggered by acetylcholine and histamine .
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ This triggers intestinal gastrin to be released.
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    .Partially-digested food fills the duodenum.^ Partially-digested food fills the duodenum .
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ Once the food bolus is partially digested, it moves on to the duodenum.

    ^ The bile then comes in contact with the partially-digested food in the duodenum .

    .This triggers intestinal gastrin to be released.^ This triggers intestinal gastrin to be released.
    • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

    ^ When food first contacts the intestines, it stimulates the cells of the duodenum to release a hormone called intestinal gastrin, believed to be identical to gastrin.

    ^ Once food is in the stomach, its presence there triggers the release of the hormone, gastrin into the blood system.
    • Effects of Antacids on Pepsin 19 January 2010 18:50 UTC biology.clc.uc.edu [Source type: FILTERED WITH BAYES]

    Enterogastric reflex inhibits vagal nuclei, activating sympathetic fibers causing the pyloric sphincter to tighten to prevent more food from entering, and inhibits local reflexes.

Oral cavity

.In humans, digestion begins in the oral cavity where food is chewed.^ The muscular walls of the esophagus produce wave-like contractions ( peristalsis ) that help propel food from the oral cavity to the stomach.
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.Saliva is secreted in large amounts (1-1.5 litres/day) by three pairs of exocrine salivary glands (parotid, submandibular, and sublingual) in the oral cavity, and is mixed with the chewed food by the tongue.^ The 'canal' includes the oral cavity, pharynx, esophagus (which includes a crop in some birds), stomach (proventriculus & gizzard), small intestine, & large intestine.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ The muscular walls of the esophagus produce wave-like contractions ( peristalsis ) that help propel food from the oral cavity to the stomach.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ In these large ceca, food particles are acted upon by cecal secretions, bacteria, and fungi and nutrients can be absorbed.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.There are two types of saliva.^ There are two types of saliva.
  • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

^ There are basically two types of food on earth.
  • Optimal Digestion 19 January 2010 18:50 UTC www.breathing.com [Source type: FILTERED WITH BAYES]
  • Optimal Digestion. 19 January 2010 18:50 UTC www.aboutbreathing.com [Source type: FILTERED WITH BAYES]

^ There are two different types of vitamins, classified by the fluid in which they can be dissolved: water -soluble vitamins (all the B vitamins and vitamin C) and fat-soluble vitamins (vitamins A, D, and K).
  • Food and Nutrient Digestion - Overview 19 January 2010 18:50 UTC www.nutristrategy.com [Source type: Reference]

.One is a thin, watery secretion, and its purpose is to wet the food.^ One is a thin, watery secretion, and its purpose is to wet the food.
  • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

^ Your food may spend as long as 4 hours in the small intestine and will become a very thin, watery mixture.
  • Your Digestive System 19 January 2010 18:50 UTC kidshealth.org [Source type: General]

^ There is a thin epithelium, no villi, a few glands secreting mucus, and a thick muscle layer, which propels the food by peristalsis.
  • HUMAN DIGESTION 19 January 2010 18:50 UTC www.wiziq.com [Source type: General]

.The other is a thick, mucous secretion, and it acts as a lubricant and causes food particles to stick together and form a bolus.^ In these large ceca, food particles are acted upon by cecal secretions, bacteria, and fungi and nutrients can be absorbed.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

The saliva serves to clean the oral cavity and moisten the food, and contains digestive enzymes such as salivary amylase, which aids in the chemical breakdown of polysaccharides such as starch into disaccharides such as maltose. .It also contains mucous, a glycoprotein which helps soften the food into a bolus.^ This 'juice' contains a bicarbonate solution that helps neutralize the acids coming into the intestine from the stomach plus a variety of digestive enzymes.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

Swallowing transports the chewed food into the oesophagus, passing through the oropharynx and hypopharynx. .The mechanism for swallowing is coordinated by the swallowing center in the medulla oblongata and pons.^ This reflex is coordinated by the vomiting center in the medulla oblongata.
  • Digestion and Absorption of Food - Biology Online 19 January 2010 18:50 UTC www.biology-online.org [Source type: Academic]

^ The mechanism for swallowing is coordinated by the swallowing center in the medulla oblongata and pons .
  • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

^ Sensory impulses travel to the vomiting center in the medulla oblongata, which initiates motor responses.

.The reflex is initiated by touch receptors in the pharynx as the bolus of food is pushed to the back of the mouth.^ The bolus of food moves to the PHARYNX and is swallowed (a complex reflex activity).

^ The reflex is initiated by touch receptors in the pharynx as the bolus of food is pushed to the back of the mouth.
  • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

^ The food bolus is swallowed by an involuntary reflex action through the pharynx (the back of the mouth).
  • HUMAN DIGESTION 19 January 2010 18:50 UTC www.wiziq.com [Source type: General]

Pharynx

.The pharynx is the part of the neck and throat situated immediately posterior to (behind) the mouth and nasal cavity, and cranial, or superior, to the esophagus.^ The 'canal' includes the oral cavity, pharynx, esophagus (which includes a crop in some birds), stomach (proventriculus & gizzard), small intestine, & large intestine.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.It is part of the digestive system and respiratory system.^ Although not part of the digestive system in an anatomical sense, some birds, like hawks and owls , use their feet and talons to capture prey.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

Because both food and air pass through the pharynx, a flap of connective tissue, the epiglottis closes over the trachea when food is swallowed to prevent choking or asphyxiation.
.The oropharynx is that part of the pharynx which lies behind the oral cavity and is lined by stratified squamous epithelium.^ The 'canal' includes the oral cavity, pharynx, esophagus (which includes a crop in some birds), stomach (proventriculus & gizzard), small intestine, & large intestine.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.The nasopharynx lies behind the nasal cavity and like the nasal passages is lined with ciliated columnar pseudostratified epithelium.^ Villi are lined with columnar epithelium (EP), including goblet cells (arrows) that secrete mucus.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

Like the oropharynx above it the hypopharynx (laryngopharynx) serves as a passageway for food and air and is lined with a stratified squamous epithelium. It lies inferior to the upright epiglottis and extends to the larynx, where the respiratory and digestive pathways diverge. At that point, the laryngopharynx is continuous with the esophagus. During swallowing, food has the "right of way", and air passage temporarily stops.

Esophagus

The esophagus is a narrow muscular tube about 25 centimeters long which starts at pharynx at the back of the mouth, passes through the thoracic diaphragm, and ends at the cardiac orifice of the stomach. .The wall of the esophagus is made up of two layers of smooth muscles, which form a continuous layer from the esophagus to the open and contract slowly, over long periods of time.^ The muscular walls of the esophagus produce wave-like contractions ( peristalsis ) that help propel food from the oral cavity to the stomach.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.The inner layer of muscles is arranged circularly in a series of descending rings, while the outer layer is arranged longitudinally.^ The inner layer of muscles is arranged circularly in a series of descending rings, while the outer layer is arranged longitudinally.
  • Digestion System Hinojosa 19 January 2010 18:50 UTC www.slideshare.net [Source type: Reference]

^ These waves are generated by pacemaker cells in the longitudinal smooth muscle layer and are spread out by gap junctions.
  • Digestion and Absorption of Food - Biology Online 19 January 2010 18:50 UTC www.biology-online.org [Source type: Academic]

^ The muscularis has three (rather than two) layers of smooth muscle: an outer longitudinal layer, a middle circular layer, and an inner oblique layer.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

At the top of the esophagus, is a flap of tissue called the epiglottis that closes during swallowing to prevent food from entering the trachea (windpipe). .The chewed food is pushed down the esophagus to the stomach through peristaltic contraction of these muscles.^ It is a muscle and contracts to move the food along the path to the stomach.

^ Waves of muscle contractions called peristalsis force food down through the esophagus to the stomach.
  • Digestive System 19 January 2010 18:50 UTC kidshealth.org [Source type: FILTERED WITH BAYES]

^ Food then reaches the stomach through the pharynx and esophagus.
  • Digestion and Absorption of Food - Biology Online 19 January 2010 18:50 UTC www.biology-online.org [Source type: Academic]

It takes only about seven seconds for food to pass through the esophagus and no digestion takes place.

Stomach

.The stomach is a small,'J'-shaped pouch with walls made of thick, elastic muscles, which stores and helps break down food.^ The enzymes help break down fats, proteins, and carbohydrates.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ The muscular walls of the esophagus produce wave-like contractions ( peristalsis ) that help propel food from the oral cavity to the stomach.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.Food which has been reduced to very small particles is more likely to be fully digested in the small intestine, and stomach churning has the effect of assisting the physical disassembly begun in the mouth.^ With a change in diet from medium-small mussels (Mytilus edulis) to a diet of soft food pellets, gizzard mass was reduced by almost 50% in about 8 days.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ It also indicates which foods are most likely to be digested well together.
  • digestion - Lulu.com 19 January 2010 18:50 UTC www.lulu.com [Source type: General]

^ The 'canal' includes the oral cavity, pharynx, esophagus (which includes a crop in some birds), stomach (proventriculus & gizzard), small intestine, & large intestine.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.In ruminants who are able to digest fibrous material (primarily cellulose), use fore-stomachs and repeated chewing to further the disassembly.^ At various times and under various conditions, ceca are the site for (1) fermentation and further digestion of food (especially for the breakdown of cellulose) and absorption of nutrients, (2) production of antibodies, and (3) the use and absorption of water and nitrogenous components (Clench 1999).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.Rabbits and some other animals pass material through their entire digestive systems twice.^ Although not part of the digestive system in an anatomical sense, some birds, like hawks and owls , use their feet and talons to capture prey.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

Most birds ingest small stones to assist in mechanical processing in gizzards.
.Food enters the stomach through the cardiac orifice where it is further broken apart and thoroughly mixed with gastric acid, pepsin and other digestive enzymes to break down proteins.^ The enzymes help break down fats, proteins, and carbohydrates.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ The gastric reflux allows material in the gizzard to reenter the proventriculus for additional treatment with acid and pepsin.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Bile emulsifies fats (or, in other words, breaks fats down into tiny particles).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.The enzymes in the stomach also have an optimum, meaning that they work at a specific pH and temperature better than any others.^ Adjustments of gastric pH, motility and temperature during long-term preservation of stomach contents in free-ranging incubating King Penguins.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

The acid itself does not break down food molecules, rather it provides an optimum pH for the reaction of the enzyme pepsin and kills many microorganisms that are ingested with the food. It can also denature proteins. This is the process of reducing polypeptide bonds and disrupting salt bridges which in turn causes a loss of secondary, tertiary or quaternary protein structure. .The parietal cells of the stomach also secrete a glycoprotein called intrinsic factor which enables the absorption of vitamin B-12.^ Proventriculus - also called the glandular stomach; receives food from the esophagus & secretes mucus, HCl, and pepsinogen.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

Other small molecules such as alcohol are absorbed in the stomach, passing through the membrane of the stomach and entering the circulatory system directly. Food in the stomach is in semi-liquid form, which upon completion is known as chyme.
The transverse section of the alimentary canal reveals four (or five, see description under mucosa) distinct and well developed layers within the stomach:
  • Serous membrane, a thin layer of mesothelial cells that is the outermost wall of the stomach.
  • Muscular coat, a well-developed layer of muscles used to mix ingested food, composed of three sets running in three different alignments. .The outermost layer runs parallel to the vertical axis of the stomach (from top to bottom), the middle is concentric to the axis (horizontally circling the stomach cavity) and the innermost oblique layer, which is responsible for mixing and breaking down ingested food, runs diagonal to the longitudinal axis.^ The muscular walls of the esophagus produce wave-like contractions ( peristalsis ) that help propel food from the oral cavity to the stomach.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    .The inner layer is unique to the stomach, all other parts of the digestive tract have only the first two layers.
  • Submucosa, composed of connective tissue that links the inner muscular layer to the mucosa and contains the nerves, blood and lymph vessels.
  • Mucosa is the extensively folded innermost layer.^ Photomicrograph (50X) of a cross section through the proventriculus showing folds of mucous membrane (P); deep proventricular glands (GP); capsule (connective tissue) around the glands (arrow head); muscle layer (m); serosa (connective tissue) with blood vessels (S), and the lumen (L) (From: Catroxo et al.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ Once produced, the B-lymphocytes migrate to lymphoid tissue in other parts of the body & the bursa of Fabricius atrophies.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ Lymphoid ceca are not important in digestion but contain lymphocytes (white blood cells) that produce antibodies (Clench 1999).
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    It can be divided into the epithelium, lamina propria, and the muscularis mucosae, though some consider the outermost muscularis mucosae to be a distinct layer, as the it develops from the mesoderm rather than the endoderm (thus making a total of 5 layers). .The epithelium and lamina are filled with connective tissue and covered in gastric glands that may be simple or branched tubular, and secrete mucus, hydrochloric acid, pepsinogen and rennin.^ The cuticle is secreted by simple tubular glands (see photomicrograph below).
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ Photomicrograph (210X) of longitudinal section of the gizzard showing folds of mucous membrane lined by simple prismatic epithelium (P); simple tubular glands (Gs) in the lamina propria constituted by connective tissue (Lp); secretion of glands (S) that are continuous with the cuticle (or koilin); (C), part of muscle layer (m), interpersed with bundles of connective tissue (Tc) (From: Catroxo et al.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ Proventriculus - also called the glandular stomach; receives food from the esophagus & secretes mucus, HCl, and pepsinogen.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    The mucus lubricates the food and also prevents hydrochloric acid from acting on the walls of the stomach.

Small intestine

.After being processed in the stomach, food is passed to the small intestine via the pyloric sphincter.^ The stomach prepares the food for complete digestion in the small intestine.

^ The second phase of digestion begins when food passes from the stomach into the small intestine.
  • Digestive Enzymes Improve Digestion even with Occasional Indigestion Heartburn with bromelain pepsin, papain. 19 January 2010 18:50 UTC www.lifeplusvitamins.com [Source type: FILTERED WITH BAYES]

^ The stomach processes the food into a usable form ( chyme ) for entry into the small intestine.

The majority of digestion and absorption occurs here after the milky chyme enters the duodenum. Here it is further mixed with three different liquids:
.
  • Bile, which emulsifies fats to allow absorption, neutralizes the chyme and is used to excrete waste products such as bilin and bile acids.^ Their kidneys extract nitrogenous wastes from the bloodstream, but instead of excreting it as urea dissolved in urine as we do, they excrete it in the form of uric acid.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ Bile emulsifies fats (or, in other words, breaks fats down into tiny particles).
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ For example, passive absorption of nutrients such as fat-soluble vitamins is not subject to modulation by diet.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    Bile is produced by the liver and then stored in the gallbladder. .The bile in the gallbladder is much more concentrated.
  • Pancreatic juice made by the pancreas.
  • Intestinal enzymes of the alkaline mucosal membranes.^ Emulsification is important because it physically breaks down fats into particles than can then be more easily digested by enzymes (lipase produced by intestinal cells and the pancreas).
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    ^ This 'juice' contains a bicarbonate solution that helps neutralize the acids coming into the intestine from the stomach plus a variety of digestive enzymes.
    • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

    The enzymes include maltase, lactase and sucrase (all three of which process only sugars), trypsin and chymotrypsin.
.As the pH level changes in the small intestines and gradually becomes basic, more enzymes are activated further that chemically break down various nutrients into smaller molecules to allow absorption into the circulatory or lymphatic systems.^ At various times and under various conditions, ceca are the site for (1) fermentation and further digestion of food (especially for the breakdown of cellulose) and absorption of nutrients, (2) production of antibodies, and (3) the use and absorption of water and nitrogenous components (Clench 1999).
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ The enzymes help break down fats, proteins, and carbohydrates.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Nevertheless, intestinal glucose transport rates do not vary with dietary carbohydrate levels in American Robins, House Sparrows, and Yellow-rumped Warblers.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.Small, finger-like structures called villi, each of which is covered with even smaller hair-like structures called microvilli improve the absorption of nutrients by increasing the surface area of the intestine and enhancing speed at which nutrients are absorbed.^ Villi are projections from the intestinal wall that increase the amount of surface area available for absorption.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ Further increasing the surface area are the numerous microvilli of the cells lining the surface of the villi.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.Blood containing the absorbed nutrients is carried away from the small intestine via the hepatic portal vein and goes to the liver for filtering, removal of toxins, and nutrient processing.^ Inside each villus are blood vessels that absorb nutrients for transport throughout the body.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.The small intestine and remainder of the digestive tract undergoes peristalsis to transport food from the stomach to the rectum and allow food to be mixed with the digestive juices and absorbed.^ The 'canal' includes the oral cavity, pharynx, esophagus (which includes a crop in some birds), stomach (proventriculus & gizzard), small intestine, & large intestine.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ The muscular walls of the esophagus produce wave-like contractions ( peristalsis ) that help propel food from the oral cavity to the stomach.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

^ This 'juice' contains a bicarbonate solution that helps neutralize the acids coming into the intestine from the stomach plus a variety of digestive enzymes.
  • Bird Digestion 19 January 2010 18:50 UTC people.eku.edu [Source type: Academic]

.The circular muscles and longitudinal muscles are antagonistic muscles, with one contracting as the other relaxes.^ The longitudinal muscles contract, increasing the pressure.

^ Made primarily of cardiac muscle, the heart serves as two separate pumps, one for pulmonary circulation and the other for systemic circulation.
  • BioEd Online Slides: digestion, human systems, human anatomy, pancreas 19 January 2010 18:50 UTC www.bioedonline.org [Source type: Academic]

^ Take a deep breath, raising the soft palate, closing the epiglottis, relaxing the circular muscles at the bottom of the esophagus, contracting the diaphragm so that it presses downward on the stomach, and contracting the abdominal wall muscles to increase the pressure in the abdominal cavity.

When the circular muscles contract, the lumen becomes narrower and longer and the food is squeezed and pushed forward. .When the longitudinal muscles contract, the circular muscles relax and the gut dilates to become wider and shorter to allow food to enter.^ It can be subdivided into circular muscle (which squeezes the gut when it contracts) and longitudinal muscle (which shortens the gut when it contracts).
  • BiologyMad A-Level Biology 19 January 2010 18:50 UTC www.biologymad.com [Source type: FILTERED WITH BAYES]

^ The longitudinal muscles contract, increasing the pressure.

^ What is the word for the coordinated wave of smooth muscle contraction that propels a bolus of food forward through the esophagus?
  • Human Physiology, Stark, Digestion 19 January 2010 18:50 UTC starklab.slu.edu [Source type: Academic]

Large intestine

After the food has been passed through the small intestine, the food enters the large intestine. Within it, digestion is retained long enough to allow fermentation due to the action of gut bacteria, which breaks down some of the substances which remain after processing in the small intestine; some of the breakdown products are absorbed. In humans, these include most complex saccharides (at most three disaccharides are digestible in humans). In addition, in many vertebrates, the large intestine reabsorbs fluid; in a few, with desert lifestyles, this resorption makes continued existence possible.
In humans, the large intestine is roughly 1.5 meters long, with three parts: the cecum at the junction with the small intestine, the colon, and the rectum. The colon itself has four parts: the ascending colon, the transverse colon, the descending colon, and the sigmoid colon. The large intestine absorbs water from the bolus and stores feces until it can be egested. .Food products that cannot go through the villi, such as cellulose (dietary fiber), are mixed with other waste products from the body and become hard and concentrated feces.^ You’ll understand your body, know what can go wrong, and wh y certain foods can be bad for you.
  • digestion - Lulu.com 19 January 2010 18:50 UTC www.lulu.com [Source type: General]

The feces is stored in the rectum for a certain period and then the stored feces is eliminated from the body due to the contraction and relaxation through the anus. The exit of this waste material is regulated by the anal sphincter.

Skye digestion

The presence of fat in the small intestine produces hormones which stimulate the release of lipase from the pancreas, largely to the liver for further processing, or to fat tissue for storage.

Digestive hormones

Action of the major digestive hormones
.There are at least five hormones that aid and regulate the digestive system in mammals.^ To make things quick and easy for the reader, each listing is assigned a “Raven Digestion Score” based on a five star system.
  • digestion - Lulu.com 19 January 2010 18:50 UTC www.lulu.com [Source type: General]

There are variations across the vertebrates, as for instance in birds. Arrangements are complex and additional details are regularly discovered. For instance, more connections to metabolic control (largely the glucose-insulin system) have been uncovered in recent years.
  • Gastrin - is in the stomach and stimulates the gastric glands to secrete pepsinogen(an inactive form of the enzyme pepsin) and hydrochloric acid. .Secretion of gastrin is stimulated by food arriving in stomach.^ The presence of food dilutes the hydrochloric acid, so stomach pH is a little higher when food is present, stimulating the secretion of more gastric juice.
    • Effects of Antacids on Pepsin 19 January 2010 18:50 UTC biology.clc.uc.edu [Source type: FILTERED WITH BAYES]

    ^ Gastrin and nerve impulses stimulate contraction of the lower esophageal sphincter, increase motility of the stomach, and relax the pyloric sphincter.
    • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

    ^ Gastrin causes the stomach to produce an acid for dissolving and digesting some foods.

    .The secretion is inhibited by low pH .
  • Secretin - is in the duodenum and signals the secretion of sodium bicarbonate in the pancreas and it stimulates the bile secretion in the liver.^ These same hormones also stimulate bile secretion into the duodenum.

    ^ Secretin stimulates the secretion of bile that is rich in bicarbonate ions.

    ^ Secretions from the liver and pancreas are used for digestion in the duodenum.

    This hormone responds to the acidity of the chyme.
  • Cholecystokinin (CCK) - is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gall bladder. This hormone is secreted in response to fat in chyme.
  • Gastric inhibitory peptide (GIP) - is in the duodenum and decreases the stomach churning in turn slowing the emptying in the stomach. Another function is to induce insulin secretion.
  • Motilin - is in the duodenum and increases the migrating myoelectric complex component of gastrointestinal motility and stimulates the production of pepsin.

Significance of pH in digestion

.Digestion is a complex process which is controlled by several factors.^ How is the digestive process controlled?

^ Anaerobic Digestion (AD) is a process whereby organic waste is broken down in a controlled, oxygen free environment by bacteria naturally occurring in the waste material.
  • Anaerobic Digestion (AD) Technical Pages. Anaerobic treatment and disposal. 19 January 2010 18:50 UTC www.anaerobic-digestion.com [Source type: FILTERED WITH BAYES]
  • Anaerobic Digestion (AD) Technical Pages. Anaerobic treatment and disposal. 19 January 2010 18:50 UTC www.anaerobic-digestion.com [Source type: FILTERED WITH BAYES]

^ Complex carbohydrates that resist the enzyme degradation, such as fiber and resistant starch, remain, as do a small amount of other food molecules and nutrients that have escaped the digestion process.
  • WHFoods: How Does Digestion Work and How Can I Improve Mine? (Animated graphics) 19 January 2010 18:50 UTC www.whfoods.com [Source type: FILTERED WITH BAYES]

.pH plays a crucial role in a normally functioning digestive tract.^ It functions best at a pH of 5-6, so its role is limited.

^ Describe the importance of the pH level in various regions of the digestive tract.

^ Faulty digestion also plays a role in toxicity of our system.
  • Poor Digestion Can Cause Fatigue 19 January 2010 18:50 UTC www.naturalways.com [Source type: FILTERED WITH BAYES]

.In the mouth, pharynx, and esophagus, pH is typically about 6.8, very weakly acidic.^ Several specialized compartments occur along this length: mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.

^ Mouth, pharynx, esophagus, stomach, small intestines (duodenum, jejunum, ileum), large intestines (ascending colon, transverse colon, descending colon), rectum, anus .
  • DIGESTION 19 January 2010 18:50 UTC www.auburn.edu [Source type: Academic]

^ When food is first swallowed, it passes from the mouth into the pharynx, a funnel-shaped tube that extends from the external nares to the esophagus posteriorly and the larynx anteriorly.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

.Saliva controls pH in this region of the digestive tract.^ Describe the importance of the pH level in various regions of the digestive tract.

^ It seems probable that this control is in reserve, although there are parts of the digestive tract in which it is of paramount importance.
  • Unit VI - Digestion 19 January 2010 18:50 UTC www.nd.edu [Source type: FILTERED WITH BAYES]

Salivary amylase is contained in saliva and starts the breakdown of carbohydrates into monosaccharides. .Most digestive enzymes are sensitive to pH and will not function in a low-pH environment like the stomach.^ What is the intestinal enzyme that functions to digest fat?
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ There are two basic categories: digestive enzymes which work in the stomach breaking down food particles before their...
  • digestion news and articles 19 January 2010 18:50 UTC www.naturalnews.com [Source type: FILTERED WITH BAYES]

^ Pepsinogen needs the low stomach pH and hydrochloric acid for conversion to pepsin.
  • Effects of Antacids on Pepsin 19 January 2010 18:50 UTC biology.clc.uc.edu [Source type: FILTERED WITH BAYES]

A pH below 7 indicates an acid, while a pH above 7 indicates a base; the concentration of the acid or base, however, does also play a role.
pH in the stomach is very acidic and inhibits the breakdown of carbohydrates while there. The strong acid content of the stomach provides two benefits, both serving to denature proteins for further digestion in the small intestines, as well as providing non-specific immunity, retarding or eliminating various pathogens.[citation needed]
.In the small intestines, the duodenum provides critical pH balancing to activate digestive enzymes.^ The intestinal phase of gastric digestion is due to activation of receptors in the small intestine.
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

^ Duodenum First 30cm of the small intestine.

^ What is the intestinal enzyme that functions to digest fat?
  • Digestion 19 January 2010 18:50 UTC www1.fccj.edu [Source type: Academic]

.The liver secretes bile into the duodenum to neutralise the acidic conditions from the stomach.^ These same hormones also stimulate bile secretion into the duodenum.

^ When a bit of fat enters the duodenum, a chemical message is sent to the brain which then signals the stomach to cease releasing more material into the duodenum until it has taken care of the fat.
  • Digestion 19 January 2010 18:50 UTC www.tuberose.com [Source type: FILTERED WITH BAYES]

^ CCK is secreted by the duodenum, the first segment of the small intestine, and causes the release of digestive enzymes and bile from the pancreas and gall bladder, respectively.

Also the pancreatic duct empties into the duodenum, adding bicarbonate to neutralize the acidic chyme, thus creating a neutral environment. .The mucosal tissue of the small intestines is alkaline, creating a pH of about 8.5, thus enabling absorption in a mild alkaline in the environment.^ The enzymes in the small intestine require a slightly alkaline environment to work.
  • Digestion 19 January 2010 18:50 UTC www.tuberose.com [Source type: FILTERED WITH BAYES]

^ Absorption occurs largely in the small intestine...
  • Digestion and Absorption – FREE Digestion and Absorption information | Encyclopedia.com: Find Digestion and Absorption research 19 January 2010 18:50 UTC www.encyclopedia.com [Source type: Academic]

^ Absorption of lipids by cells in the small intestine.

Uses of animal gut by humans

  • The stomachs of calves have commonly been used as a source of rennet for making cheese.
  • The use of animal gut strings by musicians can be traced back to the third dynasty of Egypt. In the recent past, strings were made out of lamb gut. With the advent of the modern era, musicians have tended to use strings made of silk, or synthetic materials such as nylon or steel. Some instrumentalists, however, still use gut strings in order to evoke the older tone quality. Although such strings were commonly referred to as "catgut" strings, cats were never used as a source for gut strings.
  • Sheep gut was the original source for natural gut string used in racquets, such as for tennis. .Today, synthetic strings are much more common, but the best gut strings are now made out of cow gut.
  • Gut cord has also been used to produce strings for the snares which provide the snare drum's characteristic buzzing timbre.^ What I am writing for The Pub is much more thought out and much less garbled.
    • Entrails: June 26th, 2009 « The Arena 20 September 2009 12:35 UTC thearenablog.net [Source type: FILTERED WITH BAYES]

    ^ I’ll be out for much of the night, but I’m more than happy you came.
    • Entrails: June 26th, 2009 « The Arena 20 September 2009 12:35 UTC thearenablog.net [Source type: FILTERED WITH BAYES]

    While the snare drum currently almost always uses metal wire rather than gut cord, the North African bendir frame drum still uses gut for this purpose.
  • "Natural" sausage hulls (or casings) are made of animal gut, especially hog, beef, and lamb. Similarly, Haggis is traditionally boiled in, and served in, a sheep stomach.
  • Chitterlings, a kind of food, consist of thoroughly washed pig's gut.
  • Animal gut was used to make the cord lines in longcase clocks and for fusee movements in bracket clocks, but may be replaced by metal wire.
  • The oldest known condoms, from 1640 AD, were made from animal intestine.[17]

See also

References

  1. ^ a b Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1. OCLC 32308337. 
  2. ^ Dusenbery, David B. (1996). “Life at Small Scale”, pp. 113-115. Scientific American Library, New York. ISBN 0-7167-5060-0.
  3. ^ Dusenbery, David B. (2009). Living at Micro Scale, p. 280. Harvard University Press, Cambridge, Mass. ISBN 978-0-674-03116-6.
  4. ^ Wooldridge K (editor) (2009). Bacterial Secreted Proteins: Secretory Mechanisms and Role in Pathogenesis. Caister Academic Press. ISBN 978-1-904455-42-4. 
  5. ^ Salyers, A. A. & Whitt, D. D. (2002). Bacterial Pathogenesis: A Molecular Approach, 2nd ed., Washington, D.C.: ASM Press. ISBN 1-55581-171-X
  6. ^ Cascales E & Christie P.J. (2003). "The versatile Type IV secretion systems". Nat Rev Microbiol 1 (2): 137–149. doi:10.1038/nrmicro753. 
  7. ^ Christie PJ, Atmakuri K, Jabubowski S, Krishnamoorthy V & Cascales E. (2005). "Biogenesis, architecture, and function of bacterial Type IV secretion systems". Ann Rev Microbiol 59: 451–485. doi:10.1146/annurev.micro.58.030603.123630. 
  8. ^ Chatterjee, SN and J Das. "Electron microscopic observations on the excretion of cell wall material by Vibrio cholerae." "J.Gen.Microbiol." "49" : 1-11 (1967) ; Kuehn, MJ and NC Kesty. "Bacterial outer membrane vesicles and the host-pathogen interaction." Genes Dev.and then the 19(22):2645-55 (2005)
  9. ^ McBroom, AJ and MJ Kuehn Release of outer membrane vesicles by Gram-negative bacteria is a novel envelope stress response. Mol. Microbiol. 63(2):545-58 (2007)
  10. ^ Boettner DR, Huston CD, Linford AS, et al. (January 2008). "Entamoeba histolytica phagocytosis of human erythrocytes involves PATMK, a member of the transmembrane kinase family". PLoS Pathog. 4 (1): e8. doi:10.1371/journal.ppat.0040008. PMID 18208324. PMC 2211552. http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.0040008. 
  11. ^ Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 76–97. ISBN 0030259827. 
  12. ^ Leege, Lissa. "How does the Venus flytrap digest flies?". Scientific American. http://www.sciam.com/article.cfm?id=how-does-the-venus-flytra. Retrieved 2008-08-20. 
  13. ^ Clarke, M.R. (1986). A Handbook for the Identification of Cephalopod Beaks. Oxford: Clarendon Press. ISBN 0-19-857603-X. 
  14. ^ Miserez, A; Li, Y; Waite, H; Zok, F (2007). "Jumbo squid beaks: Inspiration for design of robust organic composites". Acta Biomaterialia 3: 139–149. doi:10.1016/j.actbio.2006.09.004. 
  15. ^ Gordon John Larkman Ramel (2008-09-29). "The Alimentary Canal in Birds". http://www.earthlife.net/birds/digestion.html. Retrieved 2008-12-16. 
  16. ^ Levi, Wendell (1977). The Pigeon. Sumter, S.C.: Levi Publishing Co, Inc. ISBN 0853900132. 
  17. ^ "World's oldest condom". Ananova. 2008. http://www.ananova.com/news/story/sm_1870958.html?menu=news.quirkies.sexlife. Retrieved 2008-04-11. 

External links


Simple English

Digestion is the way that an organism changes a substance into nutrients. This happens in the gastrointestinal system. Humans start digesting food in the mouth. Food is chewed by the teeth. Food is swallowed, which means it goes through the oesophagus. It goes into the stomach, where it is mixed with acid.

After we swallow food, it travels down a muscular tube to the stomach. There, it is mashed into a mixture like soup. The mixture passes into the small intestine, where tiny bits of food pass into the bloodstream. The food that is still left goes into the large intestine. Finally, waste products leave the body. Digestion usually takes about 18 hours. Food stays in the stomach for about three hours.[1] If uncoiled, the small intestine would be about six meters (20 feet) long.[2] Most digestive tracts are about as long as a bus.[2]

Food slowly enters the small intestine from the stomach. This is where nutrients are taken into the blood. It then enters the large intestine. Water is taken away from it. The food that is left is called feces. The feces are stored in the rectum until it can leave the body through the anus.

References

  1. Morris, Neil; Ting Morris (1998). Jim Miles, Lynne French. ed (in English). Children's First Encyclopedia. Branka Surla, Rosie Alexander. II Bardfield Centre, Great Bardfield, Essex CM7 4SL: Miles Kelly Publishing Ltd. ISBN 1-84084-332-2. 
  2. 2.0 2.1 (in English) My First Book on the Human Body. 4 North Parade, Bath, BA1 1LF, UK: Robert Frederick Ltd. 2004. ISBN 0-7554-3506-0. 

Other websites


Citable sentences

Up to date as of December 20, 2010

Here are sentences from other pages on Digestion, which are similar to those in the above article.








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