Answer: Parathyroid glands.
- A Adrenal glands
- B Parathyroid glands
- C Pineal glands
- D Thymus lobes
Correct answer: B. Parathyroid glands
Explanation: Four parathyroid glands lie on the back of the thyroid and secrete parathormone, which raises blood calcium.
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.