Physiology Revision - Thermal Regulation

Question 1

What does endotherm and homeotherm mean?

Answer 1

What humans are:

Endotherm - generate body heat through metabolism

Homeotherm - humans maintain their body temp. within very narrow limits despite wide fluctuations in ambient temp.

Question 2

What is the significance of body core temp compared to body surface temp?

Answer 2

Body core temp is maintained while body surface temp can vary considerably

Question 3

What are the four mechanisms of heat exchange?

Answer 3

Sweating - cools down as sweat evaporates from skin

Sun Radiation

Conduction - adjacent surface brings temp up or down

Convection - Movement of either air or water surrounding skin

Question 4

What is thermoregulation?

Answer 4

Body core temp. is maintained by balancing heat gain and loss

Question 5

What are the two thermoregulatory responses to heat gain? Describe them.

Answer 5

Vasodilation - Blood vessels in the skin near the extremities dilate due to a reduction of sympathetic stimulation
- In skin away from extremities, vasodialtion also occurs due to the release of Ach from specialized sympathetic neurons

Sweating -

Question 6

What are the two thermoregulatory responses to heat loss? Describe them.

Answer 6

Vasoconstriction - decreases blood flow to periphery. This occurs as norepinephrine acts on adrenergic receptors

• Paradoxically, during long exposure to cold, skin will often show intermittent periods of vasodilation

Shivering - voluntary muscle contraction

Question 7

Define Hypothermia and hyperthermia and temps.

Answer 7

Hypothermia - body core temp below 35 C

Hyperthermia - body core temp btw 38-40.5 C

Question 8

What happens to body temp during excerise?

Answer 8

Body’s set-point is reset and maintained higher than at rest

Question 9

What is acclimatization?

Answer 9

repeated exposure to heat

considered to begin after 5-10 days of prolonged exercise in heat