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A-Level Biology OCR A

Skin Body Surface Core Blood Heat Explain Temperature

When core body temperature rises above optimum, the body responds by detecting the change via receptors, initiating vasodilation to increase heat radiation from the skin, and increasing sweating to cool the blood. It also involves lowering body hair or feathers to reduce trapped insulating air, all to maximize heat loss.

When core body temperature rises above optimum, the body responds by detecting the change via receptors, initiating vasodilation to increase heat radiation from the skin, and increasing sweating to cool the blood. It also involves lowering body hair or feathers to reduce trapped insulating air, all to maximize heat loss.

Front Explain how core body temperature is decreased if it rises above the optimum.
Back Increase in core body temp:
  • Receptors detect change & send signals through nervous system for different responses
  • Vasodilation - arterioles near surface of skin dilate - arteriovenous shunt vessels constrict, forcing blood through capillary networks close to skin - more heat radiated out
  • Increased sweating - spreads across surface of skin & as it evaporates, heat is lost, cooling blood below surface
  • Lowering body hair/feathers - erector pili muscles in skin relax, hair or feathers lie flat - avoids trapping insulating layer of air, maximising ability to cool down

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