thermoregulation

Question 1

role of blood vessels

Answer 1

warm conditions
- Vasodilation of skin arterioles
- By-pass arteriole constricted & skin arteriole dilated, more blood flows to skin surface when body needs to lose heat.
- capillaries fill with blood
- heat energy lost

cold conditions
- Vasoconstriction of skin arterioles:
- By-pass arteriole dilated & skin arteriole constricted, less blood flows to skin surface when body needs to retain heat.
- capillaries have little blood
- most blood to skin flows from arteriole to venue directly

Question 2

role by hair erector muscles

Answer 2

warm conditions
- Hair erector muscles relax when heat loss must be increased.
- little air retained against skin
- Heat is lost via convection &
conduction

cold conditions
- Hair erector muscles
contract when heat must not be lost.
- much air still retained against skin
- Retained air serves
as an insulator
against heat loss

Question 3

role by sweat glands

Answer 3

• Sweat gland produces sweat when the body needs to lose heat. The evaporation of sweat results in latent heat of vapourisation loss from the
  body and causes cooling
• sweat secreted on to skin surface
• in low humidity and moving air, evaporation occurs and causes cooling
• Sweat gland stop producing sweat when the body needs to retain heat.

Question 4

Role by fatty (adipose)
tissues

Answer 4

• Serves an insulation layer against heat loss
• this is usual for human leaving in cold climate to retain body heat when the surrounding temperature
  is low.

Question 5

Role by skeletal muscle –
shivering (not part of skin)

Answer 5

• Body experiences a sudden loss of heat
• Shivering occurs, defined as the non coordinated contraction of skeletal muscles
• Raising muscle heat production about five times
  above basal rate.

Question 6

Role by body metabolic
rate (not part of skin)

Answer 6

• Increase in body’s metabolic rate to
  increase heat production to raise
  body’s temperature
• decrease in body’s metabolic rate to
  decrease heat production to reduce
  body’s temperature

Question 7

Maintenance of
body temperature

Answer 7

Detectors: thermoreceptors at
skin, thermoreceptors in the blood
vessels, etc.

Detectors send nerve impulses to
hypothalamus, which is the
control centre

Hypothamalus sends nerve
impulses to the various effectors
to restore changes in body
temperature.