The human body is a unique system of coordinated mechanisms.
The millions of neurons serve as the structural and functional unit of the body. The neurons pick up the signals from the sensory organs and transfer them to the brain through the nerves. There are receptors in the body that pick up these signals, i.e., they first sense them and then transfer them through nerves to the brain. These receptors are also known as sensory receptors. They are located in organs such as:
Eyes, nose, ear, skin, tongue
1. Eyes- these act as the receptor for sight. The presence of rods and cones helps a person to visualize objects. Whatever we see is just an image formed by the reflection of the light transmitted by the object or any light source. Cones are the cells that helps us to see in light and rods are the cells that helps us visualize objects at night or in dark.
2. Nose- the smell receptor of the body. It takes up the smell through the olfactory receptors present in the nasal cavity. This signal is transmitted to the brain through the olfactory nerves.
3. Ear- the receptor for hearing is present in the ear, particularly in the ‘organ of Corti’ present in the cochlea that is located in the internal ear.
4. Skin- the receptor for touch is located in the skin. there are receptors for heat and cold too. It is the largest organ of the body, that covers the entire surface of the human body.
5. Tongue- the receptors of taste is located in the tongue in the form of taste buds. The apex of the tongue has receptors or taste buds for sweet, the lateral sides have receptors for salty taste whereas the posterior end has receptors for bitter and sour taste.