Exam 3

Question 1

normal core body temp

Answer 1

37* C

Question 2

above 45* C core body temp

Answer 2

may destroy proteins and enzymes and lead to death

Question 3

below 34*C core body temp

Answer 3

may cause slowed metabolism and arrhythmias

Question 4

thermal gradient from body core to skin surface

Answer 4

• ideal gradient is 4* C
• in extreme cold, may be up to 20*

Question 5

Voluntary Heat Production

Answer 5

Exercise
70-80% energy expenditure appears as heat

Question 6

Involuntary heat production

Answer 6

shivering- increases heat production by 5x
non-shivering thermogenesis- action of hormones thyroxine, catecholamines (speed up metabolism)

Question 7

Radiation

Answer 7

• transfer of heat via infrared rays
• 60% heat loss at rest
• can be method of heat gain

Question 8

Conduction

Answer 8

heat loss due to contact with another surface

Question 9

Convection

Answer 9

• heat transferred to air or water
• ex: fan pushing air past skin

Question 10

Evaporation

Answer 10

-heat from skin converts water to water vapor

Question 11

Evaporation rate depends on:

Answer 11

• temperature and relative humidity
• convective currents around the body
• amount of skin surface exposed

Question 11

skin vapor pressure

Answer 11

~32 mmHg
(the greater the gradient or difference is the greater heat loss)

Question 12

% heat loss at rest due to evaporation

Answer 12

25%

Question 13

L of sweat evaporated to kcal heat lost

Answer 13

1 L (1000 ml) sweat results in heat loss of 580 kcal
(body loses 0.58 kcal heat/ml sweat evaporated)

Question 14

Calculation of heat loss via evaporation

Answer 14

• total energy expenditure (min * kcal/min)
• total heat produced
  (kcal * energy lost as heat)
• evaporation to prevent heat gain
  (kcal / kcal/L)

Question 15

Heat produced that is not lost…

Answer 15

is stored in body tissues and will raise body temperature

Question 16

body heat gain during exercise

Answer 16

heat produced - heat loss

Question 17

amount of heat required to raise body temperature

Answer 17

specific heat of human body is 0.83 kcal/kg
(heat required to raise body tem 1* C = specific heat * body mass)

Question 18

Calculation of body temp increase during exercise

Answer 18

• total energy expenditure (min *Kcal/min)
• total heat produced
• total heat stored
• amount of heat storage to increase body temperature by 1*C
• increase in body temperature during exercise
• post-exercise body temperature

Question 19

Preoptic anterior hypothalamus (POAH)

Answer 19

• body’s “thermostat”, maintains around constant core temperature

Question 20

POAH response to increase in core temp

Answer 20

• cutaneous vasodilation, allowing increased heat loss
• stimulation of sweat glands for evaporative heat loss

Question 21

response to decrease in core temperature

Answer 21

• shivering and increased norepinephrine release
• decreased skin blood flow via vasoconstriction

Question 22

as temperature and humidity goes up…

Answer 22

the body relies on evaporative heat loss more as convective and radiative heat loss become methods for heat gain

Question 23

Heat Index

Answer 23

relative humidity added to air temperature, measure of how hot it feels

Question 24

high relative humidity reduces evaporated heat loss

Answer 24

- lowers heat loss - increases body temperature

Question 25

exercise in the heat

Answer 25

- reduced ability to lose body heat - higher sweat rate, may be as high as 4-5 L/hour, risk of dehydration

Question 26

dehydration and performance

Answer 26

dehydration of 1-2% body weight can impair performance

Question 27

hydration guidelines

Answer 27

- hydrate prior to performance - consume 150-300 ml fluid every 15-20 min - monitor urine color

Question 28

impaired exercise performance in hot environment

Answer 28

- cardiovascular dysfunction: reduced stroke volume, cardiac output, and muscle blood flow - accelerated muscle fatigue: increased radical production, decreased muscle pH, muscle glycogen depletion -central nervous system dysfunction: decreased motivation, reduced voluntary activation of motor units

Question 29

gender and age heat acclimitization

Answer 29

no difference

Question 30

Precooling

Answer 30

lowering body temp before exercise in the heat improves exercise performance combining cooling techniques increases imporvement

Question 31

acclimation

Answer 31

rapid adaptation (days to weeks) to environmnetal change

Question 32

acclimatization

Answer 32

adaptation over a long time period (weeks to months)

Question 33

acclimation and inactivity

Answer 33

acclimation is lost within days of inactivity or no heat exposure significant decline in 7 days, complete loss in 28 days

Question 34

physiological adaptations during heat acclimation (4)

Answer 34

- 10-12% increase in plasma volume to maintain blood volume, stroke volume, and sweating capacity - earlier onset of sweating and higher sweat rate - reduced skin blood flow - reduced sodium chloride loss in sweat, reduced risk of electrolyte disturbance

Question 35

Heat acclimation and heat shock proteins

Answer 35

-heat acclimation reduces the risk of heat injury in response to exposure of heat stress - protection is due to synthesis of heat shock proteins in cells, protect cells from thermal injury, stabilizing and refolding damaged proteins

Question 36

exercise in vinyl suits

Answer 36

- can promote acclimation - risk of hyperthermia - not effective for weight loss

Question 36

exercise in cool for heat acclimation

Answer 36

it works but less than training in the heat

Question 37

partial pressure

Answer 37

- % of O2, CO2, and N2 in the air is same - there is lower partial pressure of O2, CO2, and N2 at higher altitudes

Question 38

atmospheric pressure

Answer 38

decreases at higher altitude

Question 38

hypoxia

Answer 38

low partial pressure of O2 (at altitude)

Question 39

Normoxia

Answer 39

normal PO2 (sea level)

Question 40

Hyperoxia

Answer 40

high PO2 (below sea level)

Question 41

Altitude and short term anaerobic performance

Answer 41

- lower PO2 has no effect on performance - lower air resistance may improve performance

Question 42

altitude and long term aerobic performance

Answer 42

- lower PO2 results in poorer aerobic performance as it is dependent on oxygen delivery to muscle

Question 43

altitude and VO2 max

Answer 43

- decreased VO2 max at higher altitude due to lower oxygen extraction - decreased maximal cardiac output at altitude

Question 44

moderate altitude and VO2 max

Answer 44

decreased VO2 max due to decreased arterial PO2