Breaking out in a sweat T7

Question 1

Explain how body temperature is maintained during a period of intense exercise, with reference to each stage within the homeostatic control mechanism.
(5)

Answer 1

• Temp increases above normal level.
• This is detected by thermo-receptors in skin/the hypothalamus.
• Impulses pass to hypothalamus.
• Heat loss centre activated.
• Impulses sent to sweat glands.
• Evaporation of sweat causes a cooling effect.
• Impulses sent to shunt vessels in the skin.
• Shunt vessels constrict / vasodilation.
• More blood flow through skin surface capillaries.
• More heat loss via radiation.
• Body temp. falls back to normal, via negative feedback.

Question 2

What is meant by the term homeostasis.

1

Answer 2

Maintenance of a constant internal environment.

Question 3

Define negative feedback.

1

Answer 3

When an increase/decrease in the norm triggers mechanisms to return the body back to normal.

Question 4

Why is it important that core temperature remains stable?

Answer 4

• Allows a stable rate of enzyme controlled reactions.
• Temp. too low, there is an insufficient concentration of kinetic energy, enzyme and substrates less likely to move and form substrate-complex.
• Temp too high, enzymes denature.