Explain how each of the following processes contributes to the maintenance of constant internal body temperature in mammals: (a) sweating (b) shivering (c) contraction of hair erector muscles (d) vasodilation and vasoconstriction of arterioles supplying skin surface capillaries

SouravNovember 3, 2024

Answer

The maintenance of a constant internal body temperature in mammals is crucial for optimal physiological functioning, and several processes contribute to this thermoregulation. Here’s how each of the following processes plays a role:

(a) Sweating

• Mechanism: Sweating is a cooling mechanism activated when body temperature rises above the normal range. The hypothalamus detects this increase and stimulates sweat glands in the skin to produce sweat.
• Effect: As sweat evaporates from the skin surface, it absorbs heat from the body, effectively cooling the skin and the underlying blood vessels. This process helps lower body temperature and prevent overheating, especially during exercise or in hot environments.

(b) Shivering

• Mechanism: Shivering occurs when the body temperature drops below the set point. The hypothalamus responds by triggering involuntary muscle contractions (shivering).
• Effect: These rapid muscle contractions generate heat through increased metabolic activity, warming the body. Shivering is an essential response to cold environments, helping to restore normal body temperature by producing additional heat.

(c) Contraction of Hair Erector Muscles

• Mechanism: The contraction of hair erector muscles (arrector pili) occurs in response to cold temperatures. These tiny muscles are attached to hair follicles and contract when stimulated by the autonomic nervous system.
• Effect: When these muscles contract, they cause hairs to stand upright, trapping a layer of air close to the skin. This insulating layer reduces heat loss from the body by creating an air barrier, helping to maintain warmth in cold conditions.

(d) Vasodilation and Vasoconstriction of Arterioles Supplying Skin Surface Capillaries

• Vasodilation:
  • Mechanism: In response to increased body temperature, the hypothalamus signals blood vessels supplying skin capillaries to dilate (vasodilation).
  • Effect: This increases blood flow to the skin’s surface, allowing more heat to be released into the environment through radiation and convection. It helps cool down the body during overheating.
• Vasoconstriction:
  • Mechanism: When body temperature drops, the hypothalamus triggers vasoconstriction, narrowing these blood vessels.
  • Effect: This reduces blood flow to the skin’s surface, minimizing heat loss by keeping warm blood deeper within the body. This mechanism helps retain core body temperature during cold exposure.