Question

How do receptors transfer message to cell? Explain briefly.

Answer 1

cells have proteins called as receptors that bind to signaling molecule and initiate a physiological response. Different receptors are specific to different molecules.For example dopamine binds with dopamine receptor ,insulin with insulin receptor only.They subsequently transfer the signal through a sequence of molecular switches to internal signaling pathways.
few receptors can directly respond to external stimulus like light or pressure.

Answer 2

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In the body, the message between two neurons and that between neurons to the muscles is communicated with the help of chemicals known as chemical messengers.

These are recieved at the binding site of the receptor proteins. To accommodate the messenger, the shape of the receptor changes and results in the transfer of the message to the cell. Thus, chemical messengers give messages to the cell without entering into the cell.

There are two types of chemical messengers :-

(i) Hormones

(ii) Neurotransmitters

★ Hormones :

These are the chemical substances which are produced in ductless glands known as endocrine glands. They enter the blood stream and are carried to different parts of the body by the blood stream where they activate all the receptors which recognize them for message transfer.

★ Neurotransmitters :

These are small molecules which help in the transfer of nerve messages. Some common examples of neurotransmitters are acetylcholine, serotonin, dopamine, etc.

A neurotransmitter is released by nerve endings and get bound to the active site (binding site) of the closely placed target receptor in a very short time to transfer message to it. It then departs quickly after transferring the message. The receptor, then forwards the message inside the cell. After leaving the active site, the neurotransmitters undergo degradation and lose their capabilities of transferring messages (they become deactivated). The degraded products go back to the nerve endings to become active messages again.

In this way, the cycle of message transfer is repeated again.