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"Integument" redirects here; in botany, an integument is an outer membrane of an ovule, which later develops into a seed coat.
Integumentary system
Latin integumentum commune

The integumentary system (Etymology - Latin integumentum, from integere to cover; from in- + tegere to cover [1]) is the organ system that protects the body from damage, comprising the skin and its appendages[2][3] (including hair, scales, feathers, and nails). The integumentary system has a variety of functions; it may serve to waterproof, cushion and protect the deeper tissues, excrete wastes, regulate temperature and is the attachment site for sensory receptors to detect pain, sensation, pressure and temperature. In humans the integumentary system additionally provides vitamin D synthesis.

The integumentary system is the largest organ system. This system accounts for about 16 percent of your total body weight and covers 1.5-2m2 of surface area.[4] It distinguishes, separates, protects and informs the animal with regard to its surroundings. Small-bodied invertebrates of aquatic or continually moist habitats respire using the outer layer (integument). This gas exchange system, where gases simply diffuse into and out of the interstitial fluid, is called integumentary exchange.

Contents

Epidermis

This is the top layer of skin made up of epithelial cells. It does not contain blood vessels. Its main job is protection, absorption of nutrients, and homeostasis. In structure, it consists of a keratinized stratified squamous epithelium comprising four types of cells: keratinocytes, melanocytes, Merkel cells, and Langerhans' cells. The major cell of the epidermis is the keratinocyte, which produces keratin. Keratin is a fibrous protein that aids in protection. Millions of dead keratinocytes rub off every day. The majority of the skin on the body is keratinized. When cells are keratinized it means that it is waterproof. The only skin on the body that is non-keratinized is the lining of skin on the inside of the mouth. Non-keratinized cells allow water to "sit" atop the structure.

The epidermis contains different types of cells; the most common are: squamous cells, which are flat, scaly cells on the surface of the skin, basal cells, which are round cells, and melanocytes, which give the skin its color. The epidermis also contains Langerhan's cells, which are formed in the bone marrow and then migrate to the epidermis. They work in conjunction with other cells to fight foreign bodies as part of the body's immune defense system. Granstein cells play a similar role. Melanocytes create melanin, the substance that gives skin its color. These cells are found deep in the epidermis layer. Accumulations of melanin are packaged in melanosomes (membrane-bound granules). These granules form a pigment shield against UV radiation for the keratinocyte nuclei.

The epidermis itself is made up of four to five layers. From the lower to upper epidermis, the layers are named: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (the extra layer that occurs in places such as palms and soles of the feet), and the stratum corneum.
The stratum basale is the only layer capable of cell division, pushing up cells to replenish the outer layer in a process called terminal differentiation. The stratum corneum is the most superficial layer and is made up of dead cells, proteins, and glycolipids.

The protein keratin stiffens epidermal tissue to form fingernails. Nails grow from thin area called the nail matrix; growth of nails is 1 mm per week on average. The lunula is the crescent-shape area at the base of the nail, this is a lighter colour as it mixes with the matrix cells.

Dermis

The dermis is the middle layer of skin, composed of loose collective tissues such as collagen with elastin arranged in a diffusely bundled and woven pattern. These layers serve to give elasticity to the integument, allowing stretching and conferring flexibility, while also resisting distortions, wrinkling, and sagging. The dermal layer provides a site for the endings of blood vessels and nerves. Many chromatophores are also stored in this layer, as are the bases of integumental structures such as hair, feathers, and glands.

Subdermis (aka subcutaneous layer, hypodermis, or superficial fascia)

Although technically not part of the integumentary system, the subdermis is the layer of tissue directly underneath the dermis. It is mainly composed of connective and adipose tissue or fatty tissue. Its physiological functions include insulation, the storage of energy, and aiding in the anchoring of the skin. It also cushions the underlying body for extra protection against trauma.

Functions

The integumentary system has multiple roles in homeostasis. All body systems work in an interconnected manner to maintain the internal conditions essential to the function of the body. The skin has an important job of protecting the body and acts as the body’s first line of defense against infection, temperature change, and other challenges to homeostasis. Functions include:

Diseases and injuries

Possible diseases and injuries to the human integumentary system include:

References

  1. ^ MeSH Merriam+Webster+Dictionary}
  2. ^ MeSH Integumentary+System
  3. ^ Marieb, Elaine; Katja Hoehn (2007). Human Anatomy & Physiology (7th ed.). Pearson Benjamin Cummings. p. 142. 
  4. ^ Martini & Nath: "Fundamentals of Anatomy & Physiology" 8th Edition, pp.158,Pearson Education, 2009

Study guide

Up to date as of January 14, 2010

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BASIC SKIN PARTS:

EPIDERMIS LAYER: Dead, Alive.

DERMIS LAYER: Contains: Sweat gland, oil gland, nerves, receptors, hair, smooth muscle, blood vessels.

"FATTY LAYER": Contains: Blood vessels.


Simple English

The integumentary system is everything covering the outside of our bodies. This means skin, hair, scales, nails, sweat glands and their products (sweat and mucus). The name comes from the Latin integumentum, which means 'a covering'.

Contents

The integumentary system

Skin, hair, scales, feathers and nails make up the integumentary system.

Skin

There are two layers of skin:

  1. Epidermis
  2. Dermis
  3. Subcutaneous tissue (The subcutaneous tissue is not part of the skin, but it is in the integumentary system)

Glands

There are four types of gland:

Functions

The integumentary system has lots of different functions, it:

References

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