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The human nose is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones and the nasal cartilages, including the nasal septum, which separates the nostrils and divides the nasal cavity into two. The nose has an important function in breathing.
The nasal septum divides the cavity into two cavities, [1] also known as fossae. [2] Each cavity is the continuation of one of the two nostrils . The nasal cavity is the uppermost part of the respiratory system and provides the nasal passage for inhaled air from the nostrils to the nasopharynx and rest of the respiratory tract .
A nostril (or naris / ˈ n ɛər ɪ s /, pl.: nares / ˈ n ɛər iː z /) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture ...
In humans and other mammals, the anatomy of a typical respiratory system is the respiratory tract.The tract is divided into an upper and a lower respiratory tract.The upper tract includes the nose, nasal cavities, sinuses, pharynx and the part of the larynx above the vocal folds.
This cycle, which is controlled by the autonomic nervous system, has a mean duration of two and a half hours but varies widely with age, body-posture, and other conditions. [5] He further observed and documented that the turbinates in the dependent nasal fossa fill when the patient is lying down. The nasal cycle is an alternation in both time ...
Providing two cavities generates turbulence within the tight spaces, allowing air to flow quicker bidirectionally. The septal nasal cartilage is also the main structure that provides the orientation of the nose, being the midline structure of the organ. With an offset septal nasal cartilage, the nose will appear crooked to the viewer.
In cetaceans, the nose has been reduced to one or two blowholes, which are the nostrils that have migrated to the top of the head. This adaptation gave cetaceans 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.
Lying between the deep processes of the supporting cells are a number of bipolar nerve cells, the olfactory cells, each consisting of a small amount of granular protoplasm with a large spherical nucleus, and possessing two processes—a superficial one which runs between the columnar epithelial cells, and projects on the surface of the mucous ...