Thermoregulation and Homeostasis
The thermoregulatory centre in the brain monitors and controls body temperature to maintain homeostasis. This section explains how the body responds to temperature changes.
Definition: Homeostasis is the maintenance of constant internal conditions in the body.
The normal human body temperature is 37°C. The thermoregulatory centre in the hypothalamus contains receptors sensitive to blood temperature. Temperature receptors in the skin also send signals to this centre.
When body temperature is too high:
• Sweat glands release sweat onto the skin surface, which evaporates and cools the body
• Vasodilation occurs - blood vessels dilate to increase blood flow to the skin surface and release heat
Vocabulary: Vasodilation is the widening of blood vessels to increase blood flow.
When body temperature is too low:
• Vasoconstriction occurs - blood vessels narrow to reduce blood flow to the skin and conserve heat
• Shivering generates heat through muscle contractions
• Sweating stops to prevent heat loss
Highlight: The nervous system uses fast electrical signals, while the endocrine system uses slower but longer-lasting hormonal signals.
