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==Introduction==

==Introduction==

Olfaction is the sense of smell, which is the ability to perceive and distinguish odours. Most '''mammals''' have a good sense of smell, but most '''birds''' generally do not. The sense of smell is well-developed in '''carnivores''' (predators) and '''ungulates''' (prey). '''Fish''' also have a fairly well-developed sense of smell. Olfactory and gustatory receptors can combine to contribute to flavour.

Olfaction is the sense of smell, which is the ability to perceive and distinguish odours. Most '''mammals''' have a good sense of smell, but most '''birds''' generally do not. The sense of smell is well-developed in '''carnivores''' (predators) and '''ungulates''' (prey). '''Fish''' also have a fairly well-developed sense of smell. Olfactory and gustatory receptors can combine to contribute to flavour.

'''Middle nasal meatus''': Between the dorsal and ventral conchae, and communicates with the paranasal sinuses.

'''Middle nasal meatus''': Between the dorsal and ventral conchae, and communicates with the paranasal sinuses.

'''Ventral nasal meatus''': The main pathway for airflow leading to the pharynx, and is positioned between the ventral nasal concha and the floor of the nasal cavity.

'''Ventral nasal meatus''': The main pathway for airflow leading to the [[Pharynx - Anatomy & Physiology|pharynx]], and is positioned between the ventral nasal concha and the floor of the nasal cavity.

'''Common nasal meatus''': The longitudinal space on either side of the nasal septum.

'''Common nasal meatus''': The longitudinal space on either side of the nasal septum.

==Histology==

==Histology==

*Olfactory epithelium is made up of olfactory cells, sustentacular cells and basal cells. The olfactory axons  and olfactory glands are present in the lamina propria.  

Olfactory epithelium is made up of '''olfactory cells''', '''sustentacular cells''' and '''basal cells'''. The olfactory axons  and olfactory glands are present in the lamina propria. The first part of the nasal cavity, from the nostrils, is lined by keratinised stratified squamous epithelium. Sebaceous glands and hairs are also present in this region. The hairs function to keep dust out of the nasal cavity. The upper part of the nasal cavity is also lined by stratified squamous epithelium, but it is no longer keratinised. The epithelium then becomes pseudostratified columnar, and is ciliated. This is typical of the respiratory system, so this type of epithelium may also be known as respiratory epithelium. Goblet cells, which produce mucous, are present in this region of the nasal cavity. Mucous and serous glands are present in the connective tissue, the lamina propria, which lies underneath the epithelium that covers the nasal conchae. The olfactory region of the nasal cavity is formed by the membrane covering the dorsal nasal conchae. Cilia in this region are formed from olfactory cells, although they are non-motile. It is the membrane that covers these cilia that contains the olfactory receptors that are sensitive to smell, after the odours have been dissolved in the serous membrane covering the epithelium. The axons of these receptors bundle together within the lamina propria. The olfactory cells gain mechanical and metabolic support from the sustentacular cells.

*The first part of the nasal cavity, from the nostrils, is lined by keratinised stratified squamous epithelium. Sebaceous glands and hairs are also present in this region. The hairs function to keep dust out of the nasal cavity.

*The upper part of the nasal cavity is also lined by stratified squamous epithelium, but it is no longer keratinised. The epithelium then becomes pseudostratified columnar, and is ciliated. This is typical of the respiratory system, so this type of epithelium may also be known as respiratory epithelium. Goblet cells, which produce mucous, are present in this region of the nasal cavity.

*Mucous and serous glands are present in the connective tissue, the lamina propria, which lies underneath the epithelium that covers the nasal conchae.

*The olfactory region of the nasal cavity is formed by the membrane covering the dorsal nasal conchae. Cilia in this region are formed from olfactory cells, although they are non-motile. It is the membrane that covers these cilia that contains the olfactory receptors that are sensitive to smell, after the odours have been dissolved in the serous membrane covering the epithelium. The axons of these receptors bundle together within the lamina propria.

*The olfactory cells gain mechanical and metabolic support from the sustentacular cells.

==Species Differences==

==Species Differences==

*Those animals with a better sense of smell have a greater vascular supply to the mucosa of the dorsal nasal conchae.

Those animals with a better sense of smell have a greater vascular supply to the mucosa of the dorsal nasal conchae.

==Links==

==Links==

[[Nasal Cavity - Anatomy & Physiology|Nasal Cavity]]

Click here for more information on the [[Nasal Cavity - Anatomy & Physiology|Nasal Cavity]].

 

[[Category:Respiratory System - Anatomy & Physiology]]

[[Category:Respiratory System - Anatomy & Physiology]]

[[Category:Special Senses - Anatomy & Physiology]]

[[Category:Special Senses - Anatomy & Physiology]]

[[Category:Image Review]]

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[[Category:To Do - A&P]]