Answer: Persistently high hormone concentrations, reducing receptor number to limit further response.
- A Hormone analogues that cannot bind the receptor at all
- B Persistently high hormone concentrations, reducing receptor number to limit further response
- C Persistently low hormone concentrations, increasing receptor number to enhance sensitivity
- D A single brief pulse of hormone that has no lasting effect on receptor density
Correct answer: B. Persistently high hormone concentrations, reducing receptor number to limit further response
Explanation: Chronic exposure to high hormone levels can reduce the number of functional receptors on target cells (down-regulation), reducing the cell's responsiveness to prevent overstimulation.
The hypothalamus releases hormones that direct the pituitary, which releases its own trophic hormone to a target gland; that gland's hormone output then feeds back (dashed lines) to suppress both the pituitary and hypothalamus once levels are sufficient - a self-correcting loop running the entire endocrine system.
Concept context
The endocrine glands, hormone classification and mechanism of action, and negative feedback regulation.