Controlling body temperature
Introduced| English | Meaning |
|---|---|
| thermoregulation/ˌθɜːməʊˌreɡjʊˈleɪʃn/ | thermoregulation |
| sweating/ˈswetɪŋ/ | Releasing sweat that evaporates and cools the skin. |
| vasodilation/ˌvæsədɪˈleɪʃn/ | Widening of blood vessels, which can increase blood flow through them. |
| shivering/ˈʃɪvərɪŋ/ | Rapid involuntary muscle contractions that increase heat production when the body is cold. |
| vasoconstriction/ˌvæsəkənˈstrɪkʃn/ | The narrowing of blood vessels due to contraction of muscle in their walls. |
Staying at 37 °C
- Your enzymes work best at about 37 °C, so your body works hard to hold that temperature.
- This is thermoregulation 体温调节, controlled by the skin and brain.
When you are too hot, the body responds by:
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Sweating and vasodilation lose heat.
Sweating cools you because:
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Evaporation removes heat from the skin.
When you're too hot
- Sweating 出汗: water evaporates from the skin, taking heat away.
- Vasodilation 血管舒张: blood vessels near the skin widen, so more heat is lost.
Body temperature is held near 37°C by negative feedback
Controlling body temperature
sweat ↓ · shiver ↑
Body temperature returns to 37 °C: too hot → sweat; too cold → shiver.
When you are too cold, the body responds by:
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Shivering generates heat; vasoconstriction keeps it.
Rapid muscle contractions that release heat when you are cold are called ______.
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Shivering generates heat from respiration.
When you're too cold
- Shivering 颤抖: muscles contract rapidly, releasing heat from respiration.
- Vasoconstriction 血管收缩: skin blood vessels narrow, so less heat is lost.
Normal human body temperature is about how many °C?
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About 37 °C — the optimum for enzymes.
Negative feedback again
- The brain detects the change and triggers the opposite response.
- This negative feedback keeps body temperature close to 37 °C.
Vasodilation doesn't move the vessels — it widens them. The blood vessels near the skin surface widen (dilate) to lose heat, or narrow (constrict) to keep it. They don't actually move up or down.
You've got it
- the body holds about 37 °C (best for enzymes) by negative feedback
- too hot: sweating and vasodilation (lose heat)
- too cold: shivering and vasoconstriction (keep heat)
Write from losing heat
- A person is too hot.
- Sweat forms on the skin and skin arterioles widen.
What is the widening called, and what does the body do when it is too cold?
More skin blood flow and sweat both dump heat.
What does vasodilation do when you are too hot?
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Wider skin vessels let more heat leave.