Thermoregulation response to cold

Steps:

• Identify physiological mechanisms for maintaining body temperature in cold: vasoconstriction, piloerection, and shivering.
• Eliminate heat-loss responses like increased blood flow or sweating, which occur in heat.
• Recognize shivering as rapid muscle contractions to generate heat via metabolic activity.
• Match option C to shivering, the primary muscular response to cold exposure.

Why C is correct:

• Shivering involves involuntary, rapid contractions of large skeletal muscles, increasing metabolic rate to produce heat as per the principle of thermogenesis in homeostasis.

Why the others are wrong:

• A: Hair erector muscles contract (not relax) to trap air for insulation via piloerection.
• B: Vasoconstriction reduces blood flow to skin capillaries to conserve core heat.
• D: Sweat glands decrease activity in cold to prevent evaporative heat loss.

Final answer: C