The nose is the organ that extends outward in the middle of the face between the eyes and mouth.
The shape and look of the nose is dependent on the ethmoid bone and the nasal septum which is the cartilage that separates the two nostrils.
The evolutionary hypotheses of nose development in humans propose that noses are alterations of the angles of the skull because of bipedalism. Because of the change in diet that has come with modern time and the change of the skull, this caused the change of the nose’s shape. Another hypothesis is the idea that downward facing nostrils protect naval cavities from precipitation.
The nose starts to form four weeks into the gestation period and by the end of the first trimester, the main mechanisms of the nose are formed. These consist of multiple external and internal parts. The part at which the nasal bones and the frontal bones meet is the nasal root located at the top of the nose. The cartilage down the center of the nose is referred to as the anterior nasal spine.
The nose is responsible for the sense of smell and air conditioning. The part of the nose that is in charge of smelling is the olfactory system.
At the end of the nasal passage at the nasal root there is a small area of olfactory neurons that have the ability to come in contact with the air. There are bunches of cilia in the nostrils pair with molecules and the neurons to trigger the sense of smell.
Air conditioning is the other main function of the nose that is the act of changing and manipulating the air that is taken in to make it more breathable. Hairs in the nose act as filters and work to block large chunks of debris and other particles from the respiratory system. To get rid of the particles and allergens that irritate the mucosa in the nasal cavities, a sneeze can be triggered.
Image Caption: Nose diagram. Credit: The Emirr/Wikipedia (CC BY 3.0)