• Olfactory bulb – process all the odor when the olfactory
receptor or smell receptor cells which are present further inside the
olfactory bulb bring the information.
• Nasal cavity-- helps carry the gases to filter the air that
enters the lungs, along with the production of micro-organisms.
• Nostril– warms air on inhalation and removers moisture on
• Hard palate -- helps form sounds in speech. Another
function of hard palate is to allow food to be chewed while still being able
• Soft palate -- prevents food from entering the nasal cavity
during chewing and swallowing.
The nose is the organ responsible for the sense of
smell. The cavity of the nose is lined with mucous
membranes that have smell receptors connected to the
The receptors for smell are found at the olfactory
epithelium located at the very top of the nasal
passages. They are sensitive to gases and volatile
substances that have dissolved in the air
The importance of the nose
• The nose not only heats atmospheric air to body
temperature by spinning it inside the nasal cavity, but it
also moistens the air so that it does not dry out the
delicate tissue further down the airway.
• The nostrils contain tiny hairs to trap dust, pollen and other
airborne particles, and the sticky mucus catches those that
the hairs miss. Bacteria are also trapped by mucus and
killed by an enzyme found there, or by the concentration of
nitric oxide gas that the nose produces.
• The mouth, which is the start of the digestive tract, can also
be breathed through, but when this happens the body does
not receive the same benefits as when the nose is used.
Saliva doesn't do the same job as mucus, and there is no
spinning of air, warming, moistening or cleaning anywhere
near the same degree as found in the nose.
• Compared to the mouth, the nasal passages are small, and
so less air is likely to be inhaled through the nose, which is
useful if you are moving at a reasonable speed or
resting, because at these times the breathing should be of
a smallish volume.
• Yet, while the volume is less, the efficiency of the nose is
better. Due to the intricate construction of the nasal
passages, air to be driven deeper into the lungs, and as a
result, 10% more oxygen reaches the alveoli for gas
exchange and transfer into the bloodstream.
• It is harder to exhale forcefully through the nose than it is
through the mouth, which means that you are less likely to
disturb the finely tuned ratio of gases in the lungs if you use
your nose to breathe in and out with.
Common diseases of the nose
• Anosmia -- Loss of smell
• Deviated Nasal Septum -- The nasal septum is the part of
the nose that separates the two airways and the nostrils. A
deviated septum is when there is a shift from the midline or
center position. The septal deviation may be severe enough
to obstruct the passage of air through the nostrils. This
obstruction may predispose the patient to
sinusitis, infection and epistaxis (nose bleeds).
• Epistaxis (nosebleeds) -- The cause may be a trauma to the
nose, but many times the nose bleeds because of nasal
congestion due to a nasal allergy,sinus infection, or a cold
that irritates and weakens the delicate nasal lining.
• Nasal Airway Obstruction-- Blockage/obstruction of
the flow of air through the nasal passages most
commonly caused by nasal fracture, allergies, deviated
nasal septum, nasal deformity and enlarged adenoid
• Nasal Polyps-- A protruding growth from the mucous
membrane most commonly caused by chronic infection
• Rhinitis-- An inflammation of the mucous membrane of
the nose. Commonly caused by allergies . Symptoms
may include sudden attacks of sneezing, swelling of the
nasal mucosa, watery discharge from the
nose, itching, watering of the eyes.
• Sinusitis-- Sinusitis is an infection of the sinuses near
the nose. These infections usually occur after a cold or
after an allergic inflammation. There are other possible
conditions that can lead to sinusitis. These may include:
These may include:
• abnormalities in the structure of the nose
• enlarged adenoids
• infections from a tooth
• trauma to the nose
foreign objects that are stuck in the nose
Symptoms may include:
• runny nose or cold symptoms that last longer than seven to
• complaints of drip in the throat from the nose
• facial discomfort
• bad breath