The sense of sight is used to distinguish shapes, colours, size and distance.
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.
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.
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.
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.
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.