14.5 Temperature Control (Cambridge (CIE) O Level Biology): Flashcards
Exam code: 5090
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Define vasodilation.
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Define vasodilation.
Widening of the arterioles supplying skin capillaries, so more blood flows near the surface and more heat is lost.
Define vasoconstriction.
Narrowing of the arterioles supplying skin capillaries, so less blood flows near the surface and less heat is lost.
At what temperature do human enzymes work best?
Around 37°C.
What happens to enzymes if body temperature rises too high?
They denature and become less effective at catalysing reactions such as respiration.
Which part of the brain monitors the temperature of the blood?
The hypothalamus.
How does sweating help cool the body down?
Water in sweat evaporates, taking heat energy from the skin.
How does shivering help warm the body up?
Muscles contract rapidly, and this respiration releases heat energy.
How do erect hairs help keep the body warm?
They trap a layer of air that acts as an insulator, reducing heat loss.
When we are too hot, the arterioles supplying the skin capillaries widen; this is called .
When we are too hot, the arterioles supplying the skin capillaries widen; this is called vasodilation.
A layer of tissue under the dermis acts as insulation to reduce heat loss from the skin.
A layer of fatty tissue under the dermis acts as insulation to reduce heat loss from the skin.
True or False?
Vasodilation reduces the amount of heat lost from the skin.
False.
Vasodilation increases heat loss by bringing more blood near the skin surface; vasoconstriction reduces heat loss.
True or False?
Sweating cools the body because heat is used to evaporate water from the skin.
True.
As liquid water in sweat becomes water vapour, heat energy is taken from the body.
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