Exercise & Thermal Stress

Question 1

What are 2 ways the body’s heat-regulating mechanism activates?

Answer 1

-Thermal receptors in the skin provide input to the central control center
-Changes in blood temperature that perfuses the hypothalamus

Question 2

What portion of the hypothalamus detects changes in blood temperature in addition to receiving peripheral input?

Answer 2

Anterior

Question 3

What monitoring system assesses body warmth? Detect cold?

Answer 3

-Temperature of the blood assesses body warmth
-Peripheral receptors detect cold

Question 4

What is heat conduction?

Answer 4

Direct heat transfer from one molecule to another through solid, liquid, or gas

Question 5

What provides the major defense against overheating?

Answer 5

Evaporation

Question 6

Excessive sweating leads to two things.

Answer 6

Serious fluid loss and reduced plasma volume

Question 7

What happens to stroke volume during hot-weather activity?

Answer 7

-Stroke volume decreases due to fluid deficit and lower blood volume. The arterial blood is fighting between sending oxygen (blood) to the working muscles and to the periphery to transport heat for cooling to the skin’s surface.

Question 8

What happens to heart rate during hot-weather activity?

Answer 8

Heart rate increases.

Question 9

What happens to cardiac output during hot-weather exercise?

Answer 9

Cardiac output decreases.

Question 10

What is cutaneous blood flow?

Answer 10

The amount of heat that is lost to the environment.

Question 11

What takes precedence during physical activity in the heat: muscle/circulatory regulation or heat regulation?

Answer 11

Circulatory/muscle regulation

Question 12

Describe why a 100-104 degree body temperature impairs muscle activation?

Answer 12

High brain temperature decreases the central drive to exercise.

Question 13

What determines the change in core temperature with exercise?

Answer 13

Relative intensity

Question 14

How much sweat loss occurs during a moderate workout of about an hour?

Answer 14

.5-1 L

Question 15

How do acclimatized humans sustain their exceptional potential for evaporative cooling?

Answer 15

Adequate fluid replacement.

Question 16

Fluid loss coincides with the following five factors.

Answer 16

-Decreased plasma volume
-Reduced stroke volume
-Reduced skin blood flow for a given core temperature
-Increased heart rate
-General deterioration in thermoregulation efficiency

Question 17

What indicates water loss and adequacy of rehydration during and following participation in physical activity?

Answer 17

Changes in body weight

Question 18

What are three ways the aging delays the onset of sweating?

Answer 18

-Modified sensitivity of thermoreceptors
-Limited sweat glad output
-Dehydration-limited sweat output with insufficient fluid replacement

Question 19

What are the three stages of exercise hyperthermia?

Answer 19

Compensation, crisis, failure.

Question 20

What causes heat cramps?

Answer 20

An imbalance between electrolyte concentrations and body’s fluid level.

Question 21

What is the gold standard for treating exertional heat stroke?

Answer 21

Ice bath submersion

Question 22

What two mechanisms do children rely on in less stressful, cold-air environment?

Answer 22

-Augmented energy metabolism
-More effective peripheral vasoconstruction in the limbs