Human Nose: Anatomy and Olfactory System

The forward section of the nasal cavity within and above each nostril is called as a vestibule. This region of the nose is lined by stratified squamous epithelium on which stiff hairs are present which prohibit entry of dust particles coming along with the inspired air. 

The nasal cavity opens to the outside environment through the external nostrils (nares).

Nose is a most important sense organ of smell. The human nose can detect approximately 10,000 different odours. Nose also helps in the process of respiration.

Above the uppermost concha, is the olfactory bulb. It processes information about odours.
The entire nasal cavity is lined by a moist mucous membrane supplied with a large number of blood vessels.
The mucous membrane also has fine hair-like projections called the cilia which collect any debris entering the nasal cavity.
Apart from the cilia, the mucous membrane also has several cells. Some of these cells are called as secretory cells. Secretory cells secrete a thick, viscous fluid called as the mucous.

Flavour is a combination of taste and smell while eating or sipping. There are two types of receptors like gustato receptors and olfactory receptors which are involved in the sense of taste and smell respectively.

The mucous membrane of the nasal cavity contains specialized receptors responsible for the sense of smell. These are known as olfactory receptors. Optic and auditory receptors are for vision and hearing respectively.

The receptors for smell are located in the olfactory epithelium in the nose or nasal chamber thus, whatever comes near to our nose we can immediately sense its smell.

Bowman's glands are branched tubular glands in the olfactory mucous membrane. The structure of the Bowman's glands consists of an acinus in the lamina propria and a secretory duct going out through the olfactory epithelium. Bowman's glands secrete proteins, such as lysozyme, amylase and IgA similar to serous glands. 

 Both olfactory receptors and sound receptors have cilia. The different senses are taste, smell, vision and auditory senses. In humans, specialized sensory receptors are present in distinct sense organs that detect the sensory stimuli and transmit the stimuli as nerve impulses to the brain.

The following are disorders of olfaction: Anosmia inability to smell. ysosmia things smell different from memory or expectation. Hyperosmia an abnormally acute sense of smell. Hyposmia decreased ability to smell.

(A)Audition is the sense of hearing.