SIGHT
The sense of sight is used to distinguish shapes, colours, size and distance.
The eyes are the sense organs of sight.
How does light enter through the eyes?
· First, light passes though the cornea. It is transparent.
· Then, light passes though the pupil. The pupil is the hole in the centre of the iris.
· The level of light is controlled by the iris. The iris is the coloured ring.
· The lens helps the eye to focus.
· Finally, the retina captures the light.
HEARING
The
sense of hearing is used to capture sounds. Ears are the organs of
hearing.The
ears capture sounds and send them to the brain. The ears have 3 parts:
-
Outer ear. It is external. It
captures the sound through the pinna and the sound travels through the ear
canal to the middle ear.
-
Middle ear. It is internal. It
consists of the eardrum and three small bones.
-
Inner ear. It is inside your head and
it is very delicate. It consists of the cochlea and the auditory
nerve which sends the sounds to the brain.
TOUCH
The sense organ
of touch is the skin. It allows
you to identify characteristics of the objects around you.
The skin has
sensitive touch receptors that allow you to distinguish different sensations, for
example temperature, pressure and pain.
Touch
receptors send this information to the brain.
Some parts of your skin are more sensitive to touch than others, for example
your fingertips and lips.
smell.
The sense organ
of smell is inside your nose. To capture a smell, an odour must travel
though the air, enter the nose though the nostrils
and reach the nasal lining inside
the nasal cavity.
The nasal cavity has special smell receptors that
capture the odour and send signals to the olfactory bulb in
the brain. The brain interprets the information.
taste
The sense of taste allows you to capture different
flavours of food.
The tongue is the sense organ of taste. The tongue is
covered with small bumps called taste
buds.
These taste buds distinguish 5 basic flavours: sweet, salty, sour, bitter and umami.
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