Sense Organ - Nose - Anatomy of Nose & Physiology of Olfaction, For Medical and Paramedical students, B.Pharm, Pharm.D, D.Pharm, Human Anatomy & Physiology

1. ANATOMY OF NOSE &
PHYSIOLOGY OF OLFACTION
By: Dr.S.Kameshwaran.,M.Pharm.,Ph.D

2. Click to add text

3. THE NOSE
₡ The nose 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.

4.  The cartilage also 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.

6. 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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8. 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

9. ♠ The superior turbinates 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.

11. SMELL RECEPTOR:
♣ Mucus membrane 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.

12. Smell receptors
 Olfactory receptors
 Chemoreceptors
 Respond to changes
in chemical
concentrations
 Chemicals must be
dissolved in the
mucus of the nose to
activate smell
receptors

15. Magnify
chemicals
in food
nasal cavity
nerve
Brain
sensory cell
mucus lining
inside

16. PHYSIOLOGY OF SMELL
CHEMICALS IN 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.

17. Why do warm foods have stronger flavor than cold
foods?
This is because when food is heated, more chemicals
in food diffuse into the air.
Do you know ?

18. Some medicine is unpleasant to take.
You can hold your nose while taking
the medicine. This helps take away
the unpleasant feeling.

19. Our tongue can only 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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 Smelling disorders include:
− 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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