Moderate

Regulation of body temperature in homiotherms during high environmental temperature involve:

Correct answer: D. All (A), (B) and (C)

  • A. Vaso-dilation
  • B. Lowering the hairs
  • C. Reduction in sub-cutaneous fat
  • D. All (A), (B) and (C)

Explanation

When the environmental temperature is high, homotherms regulate their body temperature by vasodilation, which involves the widening of blood vessels near the skin's surface. This increases blood flow to the skin, allowing excess heat to be dissipated through radiation and convection, thereby helping to cool the body. Many mammals have erector pili muscles associated with hair follicles. In response to high environmental temperatures, these muscles relax, causing the hairs to lie flat against the skin. This change in the orientation of the hairs reduces the insulating layer of air trapped between the hairs, allowing for more efficient heat dissipation from the skin's surface. Subcutaneous fat acts as insulation, helping to retain body heat. During high environmental temperatures, homotherms may reduce subcutaneous fat through metabolic processes to enhance heat dissipation and prevent overheating. Therefore, all of these mechanisms work together to regulate body temperature in homotherms during high environmental temperatures.

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About Homeostasis

Homeostasis maintains a stable internal environment through the kidney and urinary system, thermoregulation and excretion. The kidney topics include filtration, selective reabsorption, urine formation and water balance, while thermoregulation involves sweating, vasodilation, vasoconstriction and hormonal control; excretion is different from egestion, which removes undigested food.

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