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From Wikipedia, the free encyclopedia

Head olfactory nerve.jpg
Section through human nose with olfactory nerve
Dogs have very sensitive noses
Latin 'Nasus'

Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for respiration in conjunction with the mouth. Behind the nose is the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes through the pharynx, shared with the digestive system, and then into the rest of the respiratory system. In humans, the nose is located centrally on the face; on most other mammals, it is on the upper tip of the snout.


Air conditioning

As an interface between the body and the external world, the nose and associated structures frequently perform additional functions concerned with conditioning entering air (for instance, by warming and/or humidifying it, also for flicking if moving and by mostly reclaiming moisture from the air before it is exhaled (as occurs most efficiently in camels). The nose often has inner hairs whose function is to stop unwanted particles from entering the lungs.

Sense of direction

The wet nose of dogs is useful for the perception of direction. The sensitive cold receptors in the skin detect the place where the nose is cooled the most and this is the direction a particular smell that the animal just picked up comes from.[1]

Structure in air-breathing forms

The nose of a tapir.

In amphibians and lungfish, the nostrils open into small sacs that, in turn, open into the forward roof of the mouth through the choanae. These sacs contain a small amount of olfactory epithelium, which, in the case of caecilians, also lines a number of neighbouring tentacles. Despite the general similarity in structure to those of amphibians, the nostrils of lungfish are not used in respiration, since these animals breathe through their mouths. Amphibians also have a vomeronasal organ, lined by olfactory epithelium, but, unlike those of amniotes, this is generally a simple sac that, except in salamanders, has little connection with the rest of the nasal system.[2]

In reptiles, the nasal chamber is generally larger, with the choanae being located much further back in the roof of the mouth. In crocodilians, the chamber is exceptionally long, helping the animal to breathe while partially submerged. The reptilian nasal chamber is divided into three parts: an anterior vestibule, the main olfactory chamber, and a posterior nasopharynx. The olfactory chamber is lined by olfactory epithelium on its upper surface and possesses a number of turbinates to increase the sensory area. The vomeronasal organ is well-developed in lizards and snakes, in which it no longer connects with the nasal cavity, opening directly into the roof of the mouth. It is smaller in turtles, in which it retains its original nasal connection, and is absent in adult crocodilians.[2]

Birds have a similar nose to reptiles, with the nostrils being located at the upper rear part of the beak. Since they generally have a poor sense of smell, the olfactory chamber is small, although it does contain three turbinates, which sometimes have a complex structure similar to that of mammals. In many birds, including doves and fowls, the nostrils are covered by a horny protective shield. The vomeronasal organ of birds is either under-developed or altogether absent, depending on the species.[2]

Elephants have prehensile noses.

The nasal cavities are exceptionally large in most mammals, typically occupying up to half the length of the skull. In some groups, however, including primates, bats, and cetaceans, the nose has been secondarily reduced, and these animals consequently have a relatively poor sense of smell. The nasal cavity of mammals has been enlarged, in part, by the development of a palate cutting off the entire upper surface of the original oral cavity, which consequently becomes part of the nose, leaving the palate as the new roof of the mouth. The enlarged nasal cavity contains complex turbinates forming coiled scroll-like shapes that help to warm the air before it reaches the lungs. The cavity also extends into neighbouring skull bones, forming additional air cavities known as paranasal sinuses.[2]

In cetaceans, the nose has been reduced to the nostrils, which have migrated to the top of the head, producing a more streamlined body shape and the ability to breathe while mostly submerged. Conversely, the elephant's nose has elaborated into a long, muscular, manipulative organ called the trunk.

The vomeronasal organ of mammals is generally similar to that of reptiles. In most species, it is located in the floor of the nasal cavity, and opens into the mouth via two nasopalatine ducts running through the palate, but it opens directly into the nose in many rodents. It is, however, lost in bats, and in many primates, including humans.[2]

In fish

Fish generally have a weak sense of smell, which is generally less important than taste in an aquatic environment. They do, however, possess a nose, although, unlike that of tetrapods, it has no connection with the mouth, nor any role in respiration. Instead, it generally consists of a pair of small pouches located behind the nostrils at the front or sides of the head. In many cases, each of the nostrils is divided into two by a fold of skin, allowing water to flow into the nose through one side and out through the other.[2]

The pouches are lined by olfactory epithelium, and commonly include a series of internal folds to increase the surface area. In some teleosts, the pouches branch off into additional sinus-like cavities, while in coelacanths, they form a series of tubes. Unlike tetrapods, the nasal epithelium of fishes does not include any mucus-secreting cells, since it is already naturally moist.[2]

In the most primitive living vertebrates, the lampreys and hagfish, there is only a single nostril and olfactory pouch. Indeed, the nostril also opens into the hypophysis. This is not necessarily, however, a primitive trait, but one that may have arisen later in the evolution of these particular groups. For example, the fossil heterostracans had paired nostrils, and these were also a very early vertebrate group.[2]

See also


  1. ^ Dijkgraaf S.;Vergelijkende dierfysiologie;Bohn, Scheltema en Holkema, 1978, ISBN 90 313 0322 4
  2. ^ a b c d e f g h Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 453-458. ISBN 0-03-910284-X. 

External links

1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

NOSE (D.Eng. nosu, cf. Dutch news, Swed. nos, snout; the connexion with O.Eng. nasu is obscure, cf. Ger. Nase, Lat. nares, nostrils, nasus, nose, Fr. nez), the organ of the sense of smell in man and other animals (see Olfactory System). The projecting feature above the mouth, to which the word is usually restricted in man, is, in the case of the lower animals, called snout or muzzle, or, if much prolonged, proboscis or trunk. "Nostril," the external opening into the nose, is from O.Eng. nosthyrl (thyrl or th y rl, hole or opening).

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Bible wiki

Up to date as of January 23, 2010

From BibleWiki

Anthropologists who consider the nose an important racial index (Topinard, Bertillon, Deniker, and others) in their classifications of varieties of noses have one class which they call "Jewish," or "Semitic"—prominent, arched, and "hooked" noses. It has been pointed out that this Semitic nose appears in ancient Egyptian monuments, in figures representing Semites. On the other hand, some authors show that this form of nose is not characteristically Semitic, because the modern non-Jewish Semites, particularly such as are supposed to have maintained themselves in a pure state, as the Bedouin Arabs, do not possess this characteristic nose at all. Their noses are as a rule short, straight, and often "snub," or concave. Luschan holds that the hook-nose is by no means characteristic of the Semites, and contends that the small number of arched noses that are found among the Jews is due to ancient intermixture with the Hittites in Asia Minor. He shows that other races also, as the Armenian, for instance, who have a good portion of Hittite blood in their veins, have hook-noses.

Among the modern Jews the hook-nose is not as frequently encountered as popular belief and caricaturists would lead one to believe. In the appended table are given figures of the percentage of four varieties of noses—straight ("Greek"), aquiline, or arched ("Jewish," "Semitic"), flat and broad, and "snub," or retroussé:

see table

From these figures it can be seen that the majority of noses in Jews are straight, or what is popularly known as "Greek." Over 60 per cent of the noses of Jews in the table above are of this variety, in some groups exceeding even 80 per cent. "Jewish" or arched noses are in the minority, less than 25 per cent being of this kind; in Poland, Elkind found only 6.5 per cent of Semitic noses among the Jews in Warsaw; Weissenberg, in South Russia, only 10 per cent; Yakowenko, in Lithuania, 9.79 per cent. The proportion of "snub" noses—from 3 to 6 per cent—is of interest.

Jewish "Nostrility."

A comparison of the statistics of noses in Jews and non-Jews in Russia and Galicia shows that the percentage of straight noses is about the same in both; aquiline and hook-noses are somewhat more frequently met with among the Jews, while "snub" noses are oftener encountered on non-Jewish faces. The "Jewish" nose is thus seen by statistical evidence to be not the one which is prominent, hooked, or arched. The question why artists and scientists have always considered a certain nose characteristic of the Jew has been variously explained. Beddoe claims that it is due to a characteristic tucking up of the wings. Joseph Jacobs concludes that "thenose does contribute much toward producing the Jewish expression, but it is not so much the shape of its profile as the accentuation and flexibility of the nostrils." From his composite photographs of Jewish faces he shows that when the nose is covered the Jewish expression disappears entirely, and that it is the "nostrility" which makes these composites "Jewish." "A curious experiment illustrates this importance of the nostril toward making the Jewish expression. Artists tell us that the best way to make a caricature of the Jewish nose is to write a figure 6 with a long tail (Fig. 1); now remove the turn of the twist as in Figure 2, and much of the Jewishness disappears; and it vanishes entirely when we draw the continuation horizontally as in Figure 3. We may conclude, then, as regards the Jewish nose, that it is more the Jewish nostril than the nose itself which goes to form the characteristic Jewish expression." Ripley agrees with Jacobs on this point, and concludes that next to dark hair and eyes and a swarthy skin the nostrils are the most distinctive feature among the Jews ("Races of Europe," p. 395).

The relation of the breadth of the nose to its length, known as the "nasal index," has been considered one of the best means of distinguishing the various races of mankind. Those in whom the breadth of the nose exceeds 85 per cent of its height are considered as platyrhine; those in whom the width of the nose is less than 70 per cent of its height are leptorhine; and lastly those races in which the width of the nose varies between 70 and 85 per cent of its height are classed as mesorhine. Measurements of Jewish noses show that they are mostly leptorhine, or narrow-nosed, as can be seen from the following table:

see table

Bibliography: N. D. Elkind, Evrei, Moscow, 1903; Joseph Jacobs, On the Racial Characteristics of Modern Jews, in Journal of the Anthropological Institute, 1886, xv. 23-62; A. A. Ivanowski, Ob Antropologitchekom Sostave Naselenia Rossii, Moscow, 1904; Oscar Hovorka, Die Aeussere Nase, Vienna, 1893; P. Topinard, Eléments d'Anthropologie Générale, Paris, 1885; S. Weissenberg, Die Südrussischen Juden, in Archiv für Anthropologie, 1895, vol. xxiii.

This entry includes text from the Jewish Encyclopedia, 1906.

Simple English

[[File:|thumb|right|Close-up of a human's nose]]

Elephants have long noses called trunks

A nose is a body part which allows animals to smell things. The nose also helps animals breathe. It has parts that make it work and send messages to the brain. The nose's parts include smell receptors and nerve connectors to receptors. In humans, the nose is on the front of the face. The power of the nose varies for animals. For example, dogs have a stronger sense of smell than humans.

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