Homeostasis — A/L Biology

How do I practise Homeostasis?

1 question with a worked solution

1. When human core body temperature rises above 37 °C, which physiological negative feedback responses are triggered by the thermoregulatory center in the anterior hypothalamus?
   1. A) Decreased respiration rate and lipolysis of brown adipose tissue
   2. B) Piloerection (goosebumps) and release of thyroxine
   3. C) Cutaneous vasoconstriction and shivering thermogenesis
   4. D) Cutaneous vasodilation and increased sweat gland secretion
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   Correct answer: D) Cutaneous vasodilation and increased sweat gland secretion

   The heat-loss center in the anterior hypothalamus initiates cutaneous vasodilation (increasing blood flow to skin for radiative/conductive heat dissipation) and stimulates eccrine sweat glands to promote evaporative cooling.

   Show worked solution

   Step 1: Hyperthermia stimulus: core temperature > 37 °C. Step 2: Hypothalamic integration center commands heat dissipation. Step 3: Effector responses: Vasodilation of cutaneous arterioles + diaphoresis (sweating). Step 4: Vasoconstriction and shivering are responses to hypothermia (cold). Answer: Cutaneous vasodilation and increased sweat gland secretion.
   Modelled on: the A/L Biology examination pattern

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Where does Homeostasis fit in the syllabus?

Year 2 · Term 1