A neonate exposed to a cold environment relies primarily on non-shivering thermogenesis for heat production. The specific tissue responsible for this response contains which of the following?

• A Uncoupling protein 1 (thermogenin) in mitochondria ✓
• B High myoglobin concentration for oxygen storage
• C Abundant sarcoplasmic reticulum for calcium cycling
• D Dense sympathetic cholinergic innervation

Explanation

Brown adipose tissue in neonates contains abundant mitochondria rich in uncoupling protein 1 (thermogenin), which uncouples oxidative phosphorylation from ATP synthesis, releasing energy directly as heat. Skeletal muscle relies on calcium cycling and shivering, not thermogenin. Myoglobin concentration is high in muscle for oxygen storage but is unrelated to thermogenesis. Sympathetic cholinergic innervation drives eccrine sweat glands, not brown fat thermogenesis.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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