What are Sensory Receptors?-Definition, Features and Mechanism of Action

The organs that help in receiving information from the environment are the sensory receptors. It is the part of the body that helps you to see the world around you. The ability to feel through touch is nothing but a sense of touch. The cells that sense the environment are called sensory receptors. The brain receives signals from nerves.

The body gets back instructions from the brain. Our bodies have sensory cells that detect temperature, pressure, pain, touch, smell, and hearing. They send signals to the brain that let us know what’s going on.

Features Of Sensory Receptors

Sensory receptors have the following basic features:

• They contain sensitive receptor cells. Or they contain fine branched peripheral endings of sensory neurons. These cells respond to a stimulus and create a generator potential.
• Their structure is designed to receive a specific stimulus.
• Their receptor cells synapse with afferent nerve fibers. Their stimulus travels to the central nervous system through specific neural pathways.
• The nerve impulse is translated into a specific sense in the central nervous system.

Types Of Sensory Receptors

There are different types of sensory receptors;

1. Tactile receptors
2. Georeceptors 
3.  Hygroreceptors
4. Proprioceptor
5. Photoreceptors
6. Baroreceptors
7. Chemoreceptors
8. Thermoreceptors

Mechanism Of Action Of Receptors

All receptors are transducers. They convert one form of energy into another. All nerve impulses have the same nature. Different types of receptors convert different kinds of stimuli into a local electrical potential. It is called generator potential.

The generator potential reaches the threshold potential. It opens the channels in the plasma membrane. So it creates an action potential. The impulse then travels along the axon of the cell. It moves toward a synaptic junction.

Now it has become information. It finally reaches the central nervous system or brain. All action potentials are alike. Furthermore, an action potential is an all or-none phenomenon. It occurs or it doesn’t. There are two factors that differentiate between different sensations:

 (a) Each receptor is connected with a specific site in the brain. Therefore, a stimulus directly goes to this part of the brain. Thus brain can detect a stimulus from the “wiring” of neurons For example, an optic center interprets a stimulus as a visual stimulus.

(b) The second factor is intensity. The strength of stimulus is called its intensity. The number of action potentials per unit of time also increases with the increase 

There are two factors, the first is intensity. The strength of the stimulus is called its intensity. The number of potentials per unit of time increases as the strength of the Stimulus increases. It is possible for the brain to detect stimuli from the timing of impulses.

Thus, the brain can detect a stimulus from the timing of the impulses.