Question

In hormone action, if receptor molecules are removed from target organ, the organ will
A. Continue to respond to hormone
B. Not respond to hormone
C. Continue to respond but requires higher concentrations
D. Continue to respond but in the opposite way

Answer 1

Hint: Hormones are considered as a chemical messenger which are secreted directly in the bloodstream and then carried to different parts of the body such as organs and tissues to perform the desired function. These can be paracrine in function or autocrine in function.

Complete answer:
Mode of action of hormones-
• The function of the hormone is to bind to specific proteins called hormone receptors to produce their desired effects. They regulate the metabolism and physiological functions of the target tissue.
• These receptors are present on the surface of target tissues or inside it. So, there are two types of receptors in target tissues:

Membrane-bound receptors: These are present on the cell membrane of target cells.
Intracellular receptors: These are present inside the target cell.

• The binding of the hormone with its particular receptor leads to the formation of the hormone-receptor complex. The formation of complex leads to some biochemical changes in the target tissue and only then the action takes place. Hence, the removal of receptor molecules from the target organ will lead to no response.

Hence, the correct answer is option (B).

Note: Hormone receptors can be positive. It refers to cells that have a group of proteins that bind to a specific hormone. For example, some breast cancer cells have receptors for Estrogen or Progesterone. They need these hormones to grow and hence positive for them. These cancers are fast growing as compared to hormone receptor-negative ones but regrowth can occur in a few years.