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Coordination in animals

changes also occur in the muscle fibres cavity lined with mucous membrane. The
surrounding the lens. Because of the poor nasal septum divides the cavity into two
elasticity it becomes difficult for the eye nostrils.
to focus on close objects. It is corrected
by wearing eye glasses with progressive Humans detect smell by the use of receptor
FOR ONLINE READING ONLY
lenses or bi focal lenses. cells located at the roof of the nasal cavity
in ciliated sensory cells. The nose is the
The human nose and tongue olfactory organ with cells which detect
smells in the nasal passages. See Figure
Task 2.15 2.27. The epithelial layer of the nasal

Search from the library and internet cavity has a special group of sensory
sources for animations about the structure cells with odorant receptors that can be
and functions of the human nose and stimulated when chemicals dissolve in the
tongue. Write short notes about the moisture on their surface. These sensory
searched information. cells are elongated, with cilia that reach
out in the mucus covering the epithelial
Nose layer of the nasal cavity. The mucus is
The nose is a vital organ of the olfactory secreted by certain cells in the epithelial
and respiratory systems. Structurally, it layer and it keeps the surface of the nose
consists of the external nose supported moist at all times.
by bone and cartilage, and the nasal
Front cavity
Olfactory bulb

Olfactory
mucous membrane

Olfactory epithelium

Nasopharynx

Nasal cavity

Palatine bone

Figure 2.27: Human nose

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