Zaymiey

🔬 Biology  ·  Chemical Coordination and Integration  ·  NEET

A deficiency of thyroxine in an infant, causing stunted growth and mental retardation, is:

Answer: Cretinism.

  • A Simple goitre
  • B Cretinism
  • C Acromegaly
  • D Muscle tetany

Correct answer: B. Cretinism

Explanation: Thyroxine deficiency in infancy causes cretinism - stunted growth, low metabolism and impaired mental development.

Hypothalamus-Pituitary Axis (Negative Feedback)Hypothalamusreleasing hormonePituitary("relay", not the boss)trophic hormoneTarget gland (e.g. thyroid, adrenal)hormone outputnegative feedback

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.

Read the full Chemical Coordination and Integration notes →