Nose

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Nose

Anatomically, a nose is a protuberance in vertebrate

Vertebrate

Vertebrates are members of the subphylum Vertebrata, chordates with Vertebras or Vertebral columns. The grouping sometimes includes the hagfish, which have no vertebrae, but are genetically quite closely related to lampreys, which do have vertebrae....
s that houses the nostril

Nostril

A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation....
s, or nares, which admit and expel air for respiration

Respiration (physiology)

In animal physiology, respiration is the transport of Oxygen from the outside air to the cells within Tissue s and the transport of carbon dioxide in the opposite direction....
in conjunction with the mouth

Mouth

The mouth, buccal cavity, or oral cavity is the first portion of the alimentary canal that receives food and begins digestion by mechanically breaking up the solid food particles into smaller pieces and mixing them with saliva....
. and behind the nose is the olfactory mucosa

Olfactory mucosa

The olfactory mucosa is an organ made up of the olfactory epithelium and the lamina propria, or mucus secreting glands, behind the epithelium. The mucus protects the olfactory epithelium and allows odors to dissolve so that they can be detected by olfactory receptor neurons....
and the sinuses

Paranasal sinus

Paranasal sinuses are air-filled spaces, communicating with the nasal cavity, within the bones of the skull and face....
.

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Encyclopedia

Anatomically, a nose is a protuberance in vertebrate

Vertebrate

Nostril

Respiration (physiology)

Mouth

Olfactory mucosa

Paranasal sinus

Paranasal sinuses are air-filled spaces, communicating with the nasal cavity, within the bones of the skull and face....
. Behind the nasal cavity

Nasal cavity

The nasal cavity is a large air-filled space above and behind the nose in the middle of the face....
, air next passes through the pharynx

Pharynx

FunctionsThe pharynx is part of the digestive system and respiratory system of many organisms.Because both food and Earth's atmosphere pass through the pharynx, a flap of connective tissue called the epiglottis closes over the trachea when food is swallowed to prevent choking or Pulmonary aspiration....
, shared with the digestive system, and then into the rest of the respiratory system

Respiratory system

A respiratory system?s function is to allow gas exchange. The space between the alveoli and the capillaries, the anatomy or structure of the exchange system, and the precise physiological uses of the exchanged gases vary depending on the organism....
. In humans, the nose is located centrally on the face; on most other mammal

Mammal

Mammals are a class of vertebrate animals whose name is derived from their distinctive feature, mammary glands, with which they feed their young....
s, it is on the upper tip of the snout

Snout

The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw....
.

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

Elephant

Elephants are large land mammals of the order Proboscidea and the family Elephantidae. There are three living species: the African Bush Elephant, the African Forest Elephant and the Asian Elephant ....
's nose has elaborated into a long, muscular, manipulative organ called the trunk.

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 camel

Camel

Camels are even-toed ungulates within the genus Camelus. The dromedary, one-humped or Arabian camel has a single hump and is well known for its healthy low fat milk, and the Bactrian camel has two humps....
s). The nose hairs are able to stop unwanted particles from entering the lungs.

Smelling

In most mammals, the nose is the primary large organ for smelling

Olfaction

Olfaction refers to the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates....
. As the animal sniffs, the air flows through the nose and over structures called turbinate

Turbinate

In anatomy, a nasal concha is a long, narrow and curled bone shelf which protrudes into the breathing passage of the nose. Turbinate bone refers to any of the scrolled spongy bones of the Nasal Cavity in vertebrates....
s in the nasal cavity. Turbulent flow will promote mixing of the air in the nasal cavity allowing the molecules of a newly inhaled breath of air to reach the sensitive epithelium as fast as possible. Laminar flow would imply a stationary layer of air around the epithelium only to be entered by diffusion. Sniffing will cause more turbulence also. At the olfactory epithelium, odor

Odor

An odor or odour is a volatilized chemical compound, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction....
molecules carried by the air dissolve in the fluid covered cilia of the olfactory receptor neuron

Olfactory receptor neuron

An olfactory receptor neuron, also called an olfactory sensory neuron, is the primary transduction cell in the olfactory system....
s, where they bind to specific receptor proteins

G protein-coupled receptor

G protein-coupled receptors , also known as seven transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptor, and G protein-linked receptors , comprise a large protein family of transmembrane receptors that sense molecules outside the Cell and activate inside signal transductio...
causing a depolarization

Depolarization

In biology, depolarization is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations....
of the receptor cell. At the glomeruli dendrites of many receptor cells sensitive to the same kind of odor converge and from there a signal is forwarded to the brains olfactory region.

Sense of direction

The wet nose

Rhinarium

The rhinarium is the wet, naked surface around the nostrils of the nose in most mammals. Colloquially it might be called a "wet snout".Mammals with rhinariums tend to have a stronger sense of olfaction, and the loss of the rhinarium in the haplorrhine primates is related to their decreased reliance on olfaction, being associated with o...
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.

Nose

Air conditioning

Smelling

Sense of direction

See also