The human body has 5 special sense organs which are of immense use to life. These include the
- Eyes
- Ears
- Nose
- Tongue
- Skin.
They are called special because they have specialized sensory receptors outside the brain.
These organs provide up to 80% of the sensory stimuli perceived by us.
These sense organs provide convenience and also protection to life. These organs are required daily for a variety of tasks.
Any damage to these organs will lead to disability for life.
5 Special Sense Organs in detail
Eyes
Every human being has a pair of eyes. These are the organs of sight. Hence they are prominent of all the sense organs in the body. They are connected to the brain with the optic nerve (3rd cranial nerve). Read more details on the structure and function of the eye.
Features and functions
Eyes are located in the orbital cavity of the skull near the forehead.
They are spherical in shape, with a size of 2.5cms in diameter.
The retina is the critical part of the eyes with sensory receptors in it.
The photons from the light falling on the retina are converted into an electrical impulse passed on to the optic nerve for processing.
Though two eyes are separate, they are coordinated in such a way that they function as pair.
The eyes are always kept moist by lachrymal secretions to clean the eyes.
Even if one eye is restricted, the sight can be impaired to a certain extent.
They are so delicate, and if there is damage, it could be hard to revive their function.
Loss of vision greatly affects life as one cannot see and need help from others on daily basis.
Ears
An ear is the sense organ concerned with hearing and balance.
A pair of ears are present, with one on each side of the head.
They are supplied by the 8th cranial nerve, which is called an auditory nerve.
See the structure of the ear for more details.
Features and functions
The ear has some distinct parts like the tympanic membrane, ear ossicles, vestibule, and cochlear apparatus.
The sound waves (mechanical energy) are converted into electric energy conveyed to the auditory nerve for perception.
This process is helped by the tympanic membrane, ear ossicles, and the cochlear apparatus.
If there is a problem with the ear, it impacts the balance more than the hearing part.
Nose
This is the organ of the sense of smell, but it is a part of the respiratory system in our body.
It is the vent through air enters and also leaves the lungs.
But in the roof of the nose, there are olfactory nerves that help in the perception of the sense of smell.
The chemicals in the volatile form are capture by the olfactory receptors. The chemical signal is processed into a sense of smell upon reaching the olfactory center in the brain.
Since the olfactory receptors are present on the roof of the nose, sniffing helps to concentrate the sense of smell.
These olfactory nerve endings form an olfactory bulb that transmits.
This sense of smell helps in appetite and also protects from consuming harmful foods.
Tongue
The tongue is the organ of the sense of taste.
It is a solid organ with a mass of tissue. But, yet it is quite flexible in its movements.
There are many taste buds on the tongue which have chemoreceptors.
These chemoreceptors sense the taste of chemicals in liquid form and convert to electric energy passed on to the taste center in the brain.
Basically, the tongue can recognize 4 major tastes like the sweet, salt, bitter, and sour.
However, it can also recognize many other tastes.
Skin
Skin is the organ that covers the whole body.
It also has a sense of touch due to which we perceive the senses like heat, cold, hardness, smoothness, roughness, pain, pressure, etc.
This sense of touch is essential to avoid injury to the body.