Answer: adrenaline.
- A adrenaline
- B insulin
- C thyroxine
- D estrogen
Correct answer: A. adrenaline
Explanation: The adrenal medulla releases adrenaline (epinephrine) in emergencies.
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.