Which physiological process initiates shivering in mammals encountering sudden external cold shock?

💡 Explanation

When mammals face acute cold, activation of hypothalamic thermoreceptors initiates involuntary muscle contraction because ATP hydrolysis and friction generate heat supplementing non-shivering thermogenesis, preventing hypothermia. Therefore shivering which is muscle contraction results, rather than cutaneous vasodilation, BAT apoptosis, or decreased metabolic rate, all causing further heat loss.

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