Sense Organ - Nose - Anatomy of Nose & Physiology of Olfaction

Sense Organ - Nose - Anatomy of Nose & Physiology of Olfaction

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  ANATOMY OF NOSE& PHYSIOLOGY OF OLFACTION By: Dr.S.Kameshwaran.,M.Pharm.,Ph.D
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  THE NOSE ₡ Thenose is the organ of smell ₡ Located in the middle of the face. ₡ The internal part of the nose lies above the roof of the mouth. The nose consists of: External meatus: ₡ Triangular-shaped projection in the center of the face. External nostrils: ₡ Two chambers divided by the septum. Septum: ₡ Made up primarily of cartilage and bone and covered by mucous membranes.
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   The cartilagealso gives shape and support to the outer part of the nose. Nasal passages:  Passages that are lined with mucous membranes and tiny hairs (cilia)  It helps to filter the air. Sinuses:  Four pairs of air-filled cavities,  lined with mucous membranes.
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  Nasal cavity: Nasal Vestibule,Nasal Septum, Nasal Valve, Lateral nasal Wall, Choana Bony Structure: Maxilla, Ethmoid, Palatine, Inferior Turbinate, Sphenoid. Functional apparatus: Turbinate, Meatus, Nasolacrimal duct orifice
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  NASAL CONCHA (TURBINATE) The turbinates are located laterally in the nasal cavities  Turbinates are composed of pseudostratified columnar, ciliated respiratory epithelium with a thick, vascular, and erectile glandular tissue layer.  The turbinates divide the nasal airway into four groove-like air passages, Types of turbinates: ₡ Superior turbinates ₡ Middle turbinates ₡ Inferior turbinates
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  ♠ The superiorturbinates are smaller structures, connected to the middle turbinates by nerve-endings, and serve to protect the olfactory bulb. ♠ The middle turbinates are smaller. ♠ Most inhaled airflow travels between the inferior turbinate and the middle meatus ♠ The inferior turbinates are the largest turbinates, The turbinates are responsible for ► Air flow direction ► Filtration - mucous and cilia ► Heating, ► Humidification of air inhaled through the nose.
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  SMELL RECEPTOR: ♣ Mucusmembrane of the nose cavity have smell receptors connected to the olfactory nerve. ♣ Located Within Nose (Receptors for Cr. Nerve I) ♣ The smell receptors interact with the molecules of these vapors and transmit the sensations to the brain. ♣ The smell receptors are sensitive to seven types of sensations that can be characterized as camphor, musk (Kathuri), flower, mint, ether, Acrid (Strong), Putrid (very unpleasant) ♣ The sense of smell is sometimes temporarily lost when a person has a cold.
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  Smell receptors  Olfactoryreceptors  Chemoreceptors  Respond to changes in chemical concentrations  Chemicals must be dissolved in the mucus of the nose to activate smell receptors
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  Magnify chemicals in food nasal cavity nerve Brain sensorycell mucus lining inside
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  PHYSIOLOGY OF SMELL CHEMICALSIN THE FOOD ↓ DURING BREATHING SOME CHEMICALS ENTER OUR NOSE ↓ CHEMICALS DISSOLVE IN THE MUCUS OF NOSE ↓ STIMULATE THE OLFACTORY RECEPTORS ↓ THEY PRODUCES THE ELECTRIC SIGNALS ↓ SIGNALS WERE RELAYED IN TO OLFACTORY BULB ↓ TRANSMITTED TO HIGHER CENTRE OF THE BRAIN ↓ BRAIN TO GIVE US THE ODOR OF THE FOOD.
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  Why do warmfoods have stronger flavor than cold foods? This is because when food is heated, more chemicals in food diffuse into the air. Do you know ?
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  Some medicine isunpleasant to take. You can hold your nose while taking the medicine. This helps take away the unpleasant feeling.
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  Our tongue canonly distinguish about 4 different tastes. But our nose can distinguish about 4000 different chemicals. Thus, when our nose is also used to sense the food, the food ‘tastes’ better. Our nose can tell us not only the sweet taste of ice-cream, but also whether it is chocolate flavour or not.
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  20  Smelling disordersinclude: − Anosmia: total loss of sense of smell − Dysosmia: distorted sense of smell − Hyperosmia: increased sensitivity to smell − Presbyosmia: loss of smell from normal aging
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  21 THANK U