( Chapters 12, 13, 14, 19)
1. What is a homeotherm?: humans and other animals that maintain a rather constant core
temperature
2. What is the temperature range for a human?: a human must maintain a temperature
above 34 degrees celsius and below 45 degrees celsius
a normal core temperature for humans is 37 degrees celsius
3. In general, how does the body maintain temperature during exercise?: - adjusting the amount
of heat that is lost
- the circulatory system is utilized to transport heat (due to its high heat capacity) to the
surface of the body as a means to lose heat to the environment
4. What is a common site of core temperature in a laboratory setting?: the rectum (deep body
temperature)
5. What is reliable site to measure brain temperature?: near the eardrum (tym- panic
temperature)
6. What is a thermistor?: measures deep-body temperature
7. Where is the temperature control system located?: - preoptic-anterior hypo- thalamus (POAH)
- works like a thermostat to increase heat production when temperature falls and vice versa
8. What is voluntary heat production?: exercise (heat production is large)
9. What is involuntary heat production?: - shivering (can produce heat 5x resting value)
- non-shivering thermogenesis
10.How does the body produce internal heat?: the body produces internal heat due to normal
metabolic processes
- at rest or sleeping heat production is small
11.How much energy during exercise is expended as heat?: 70-80%
12.What is non-shivering thermogensis?: - thyroxine is released from the thyroid to increase
metabolic rate
- blood levels of catecholamines (epinephrine/norepinephrine) to increase the rate of cellular
metabolism
13.What are the 4 processes that the body uses for heat loss?: 1. radiation
2. conduction
3. convection
4. evaporation
14.Which three heat loss processes require a temperature gradient to exist for heat loss?:
radiation, conduction, and convection
15.What is radiation?: - heat loss in the form of infrared rays
- surface to surface with no physical contact required
- ex: sun to earth, body to environment
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, Exercise Physiology Exam 4 Review 2024
( Chapters 12, 13, 14, 19)
- in a normal setting, 60% of heat loss is due to radiation to the surrounding
environment
16.What is conduction?: - transfer of heat from the body to the molecules of a cooler object
- requires contact
- small amounts of heat actually loss
- ex: body to cold metal chair
17.What is convection?: - heat loss in which heat is transmitted to either air or water
molecules in contact with the body
- hotter molecules are replaced by cool molecules
- ex: a fan, the wind, swimming in cool water
- water is 25x more effective, at the same temperature, than air when cooling
18.What is evaporation?: - heat is transferred from the body to water on the surface of the
skin (sweat) and then when hot enough it is converted to gas
- 25% of heat loss at rest
- most important means of heat loss during exercise
- due to a vapor pressure gradient between the skin and air
- most effective under conditions of low humidity
19.What 3 factors effect evaporation of sweat from the skin?: 1. ambient con- ditions (air
temp/relative humidity)
2. convective currents around the body
3. amount of skin surface exposed to the body
20.Why does high relative humidity reduce the rate of evaporation?: relative humidity high
reduces the vapor pressure gradient between the skin a environment resulting in a nd
reduced rate of evaporation
the
21.How do you calculate heat loss via evaporation during exericse?: - 0.58 kcals per milliliter of
water that evaporates
- 580 kcals per 1 L of sweat evaporated
22.What happens when an athlete exercises on a hot/humid day?: - evapora- tion of sweat is
decreased or eliminated
- useless water loss which does not cool the body
23.What is specific heat?: - amount of energy required to raise 1kg of body tissue by 1 degree
celsius
- specific heat of the human body = 0.83 kcal per 1 kg
- heat required = specific heat x body mass
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