Exercise and Heat Stress

Question 1

What is the normal core temperature and what makes us different from other animals?

Answer 1

A core temp of 37 degrees celsius is maintained consistently, earning us the name of homeotherms

Question 2

At 60% rest, what form of heat loss is used and how ?

Answer 2

radiation - heat is converted to infrared rays that project away to other targets

Question 3

What is the major mechanism of heat loss

Answer 3

Evaporation - liquid in the form of sweat releases warmth as the heat is transferred from a liquid to gas

Question 4

What is conduction?

Answer 4

heat is transferred from warmer object to cooler one

Question 5

What is Convection?

Answer 5

faster conduction when cooler molecules move away the warm ones (water or cool air)

Question 6

How do we survive the cold? What are the 2 responses?

Answer 6

internalize heat which maintains core temperature

1. Centralize blood flow
2. increase metabolism (increased muscular activity “shivering” and increased thyroxine and epinephrine)

Question 7

Why do we struggle with our temperature in the heat?

Answer 7

The body already produces heat, adding external factors (environment) overloads our heat load which is enhanced by the internal load (metabolism)

Question 8

How does the body sense a heat or cold load? Where are the receptors located?

Answer 8

central or peripheral temperature receptors

central - spinal cord and hypothalamus
peripheral - subcutaneous

Question 9

What happens when a cold load is sensed?

Answer 9

posterior hypothalamus processes, then shivering, vasoconstriction ( centralizing of blood flow), and increased hormones

Question 10

What happens when a heat load is sensed?

Answer 10

anterior hyphothalamus processes, vasodilation and sweating occur

Question 11

How does the body normally respond to cardio? What causes arterioles to dilate?(2 things)

Answer 11

sympathetic outputs: cardiac output increases and blood flow is centralized

metabolic waste near muscles causes arterioles to dilate (enhancing blood flow to muscles)

Question 12

What is the body’s response to cardio in the heat? (blood flow)

Answer 12

increasing blood flow to skin resulting in reduced vasoconstriction and increased vasodilation

Question 13

Why does transferring heat from body cause stress? (3 reasons)

Answer 13

1. body works to send blood to skin rather than muscle = reducing rate of venous return (messes with stroke volume) and increases heart rate
2. rely on increased cardiac output (for oxygen delivery) and increase dependence on anaerobic metabolism (for ATP demands)
3. sweat production+ = reduction in blood volume (less plasma)

Question 14

What is the first adaptation to heat? Why is it important?

Answer 14

increased blood volume, more plasma means greater venous return and lowered heart rates

Question 15

What is the second adaptation to heat?

Answer 15

increased sweat rate, but lowered electrolyte concentration to avoid blood mineral content loss

Question 16

What are the different stages of Heat Illness?

Answer 16

1. Heat cramps
2. Heat syncope - pale, tunnel vision, lightheaded,
3. Heat exhaustion - very profuse sweating,medical emergency
4. Heat Stroke - dry/hot skin, core temp is high, blood pressure drop with elevated heart, medical emergency with hyponatremia