Answer: A specialized portal blood vessel system connecting the two structures.
- A Diffusion through cerebrospinal fluid in the third ventricle according to standard texts
- B Direct axonal connections from hypothalamic neurons under typical physiological conditions
- C A specialized portal blood vessel system connecting the two structures
- D General systemic circulation, like any other hormone in general clinical practice
Correct answer: C. A specialized portal blood vessel system connecting the two structures
Explanation: Hypothalamic releasing and inhibiting hormones reach the anterior pituitary through the hypophyseal portal system, a direct vascular link, rather than through general circulation or nerve axons.
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.