Answer: Hyperthyroidism.
- A Hyperthyroidism
- B Hypothyroidism
- C Infant cretinism
- D Simple goitre
Correct answer: A. Hyperthyroidism
Explanation: Excess thyroxine (hyperthyroidism) speeds up metabolism, causing weight loss, rapid heartbeat and nervousness.
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.