The Human Nervous System (5.2) (M)

Question 1

What is body temperature is monitored and controlled by?

Answer 1

the thermoregulatory centre

Question 2

Where is the thermoregulatory centre?

Answer 2

the brain

Question 3

What does the thermoregulatory centre contain?

Answer 3

receptors sensitive to the temperature of the blood

Question 4

Explain two mechanisms that occur if body temperature is too high

Answer 4

• blood vessels supplying the skin dilate (vasodilation) - allowing more blood to flow through skin and more heat energy to be lost to the environment
• sweat is produced from the sweat glands - sweat evaporates, transferring heat energy from the skin to environment so more heat lost
• hairs lie flat as well

Both these mechanisms cause a transfer of energy from the skin to the environment

Question 5

Explain three mechanisms that occur if body temperature is too low

Answer 5

• blood vessels supplying the skin constrict (vasoconstriction) - allowing less blood to flow through skin and less heat energy to be lost to the surroundings
• skeletal muscles contract (shiver) - these muscles contractions need energy from respiration, which releases heat energy
• sweating stops - less sweat evaporates, transferring less heat energy from the skin to environment, so less heat lost
• hairs stand up as well

the first two points (constriction and shivering) are the main ones

Question 6

What temperature is the optimum bodily temperature for function?

Answer 6

37^oC

Question 7

6 marker!

Explain what happens to core body temperature and skin temperature during a long race and explain why?

Answer 7

Increase in core body temp due to an increase in respiration, releasing (heat) energy

Skin temperature decreases, because there is sweating, which evaporates and cools the skin

Question 8

4 marks

Why might an athlete overheat in humid conditions?

Answer 8

Sweat released

Cannot evaporate because of high humidity

So less heat lost

so less cooling effect

Question 9

Why did the temperature near the brain when an ice cold drink is drunk?

Answer 9

blood is cooled at the stomach

(cooled) blood flows to the brain