Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Exercise Physiology > Ch.12 > Flashcards

Ch.12 Flashcards

1
Q

What is normal core temperature?

A

37 degrees C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

An increase of temperature above what can alter normal structure of enzymes, resulting in the ability to produced ATP

A

45 C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does a decrease in body temperature below 34 C cause?

A

slowed metabolism and abnormal cardiac function (arrhythmias)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are homeotherms?

A

humans and other animals that maintain a rather constant body core temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the temperature maintenance strategy of homeotherms?

A

uses a furnace rather than a refrigerator to maintain temp at constant level

(body temp is set near high end of survival range and is held constant by continuous metabolic heat production coupled with small but continual heat loss)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What did D.B. Dill do?

A
  • well known for his contribution to acid base chemistry (henderson hasselbach equation)
  • founding members of Harvard Fatigue laboratory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What must take place in order for core temperature to remain constant?

A

amount of heat lost must match the mount of heat gained

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is one of the most important functions of the circulatory system?

A

transport heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When the body is attempting to lose heat, what occurs?

A

blood flow increased to skin as a mean of promoting heat loss to the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens when the goal of temperature regulation is to prevent heat loss?

A

blood is directed away from skin and toward the interior of the body to prevent additional heat loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

T/F there is a gradient between core temperature and he shell temperature

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

In severe conditions and normal conditions what is the temperature difference between core and skin?

A
  • severe conditions: core temp can be 20 degrees higher than skin
  • normal: difference between core and skin is 4 degrees
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What devices take measurements of deep-body temperatures?

A
  1. mercury thermometer: thermocouples or thermistors

2. ingestible core temperature pills

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In laboratory setting, a common site of core temperature is? and what does it measure?

A

rectum; measures changes in deep body temperature during exercise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Measuring temperature where is a good estimate of actual brain temperature?

A

eardrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is another alternative to measure the temperature of deep body core temperature?

A

esophagus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

In laboratory setting, common sites of temperature measurements include…

A

ear, rectum, and esophagus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

In the laboratory, measurement of what provides useful info about the temperature gradient between deep body temperature and skin?

A

measurement of skin temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How can the mean skin temperature be calculated?

A

by measuring skin temperature at several locations (using thermistors) and computing the average temperature across these locations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where is the temperature control center located?

A

Preoptic anterior hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Temperature regulation is controlled by what 2 things?

A

physical and chemical processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Heat production in the body can be classified as:

A
  1. voluntary (exercise)
  2. involuntary (shivering or biochemical heat production due to secretion of hormones such as thyroxine and catecholamines)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The body is at most, ___% to ___% efficient, ___ % to ___% of energy expended during exercise appears as heat.

A

23% to 30% efficient; 70-80% energy expended

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the primary means of increasing heat production during exposure to cold?

A

involuntary heat production by shivering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Maximal shivering can increase the body’s heat production by approximately how many times the resting value

A

five

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Increase of thyroxine release causes?

A

increase metabolic rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Increase in blood levels of catecholamines can lead to?

A

increase rate of cellular metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is nonshivering thermogenesis?

A

increase in heat production due to combined influences of thyroxine and catecholamines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Heat loss from the body occurs by four processes:

A
  1. radiation
  2. conduction
  3. convection
  4. evaporation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is radiation?

A
  • heat loss in the form of infrared rays or gain depending on environmental conditions
  • involves transfer of heat from the surface of one object to another with NO physical contact
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

At rest in comfortable environment, what percent of body heat is loss due to radiation? and how is this possible?

A

60%; possible because skin temperature is greater than temperature of surroudning objects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is conduction? Give an example

A
  • transfer of heat from the body to molecules of cooler objects in contact with its surface
  • Ex: heat loss due to conduction is transfer of heat from the body to a metal chair while a person is sitting on it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is convection? Give an example:

A
  • form of heat loss in which heat is transmitted to either air or water molecules in contact with body
  • Ex: fan moving large quantities of cool air past the skin
  • Ex: swimming in cool water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

During convection (swimming in cool water), waters effectiveness in cooling is how many times greater than that of air at the same temperature?

A

25 times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is evaporation?

A

heat is transferred from the body to water on the surface of skin

36
Q

Evaporation accounts for approximately what percent of heat loss at rest

A

25%

37
Q

What is the MOST IMPORTANT means of heat loss during exercise?

A

evaporation

38
Q

What is vapor pressure?

A

pressure exerted by water molecules that have been converted to gas

39
Q

How does evaporative cooling during exercise occur?

A
  • When body temperature rises above normal, nervous system stimulates seat glands to secrete sweat onto the surface of the skin
  • as sweat evaporates, heat is lost to the environment, which lowers skin temperature
40
Q

Evaporation of sweat from skin is dependent on 3 factors:

A
  1. ambient conditions (air temp and humidity)
  2. convective currents around the body
  3. amount of skin surface exposed to environment
41
Q

At high environmental temperatures, what is the MOST IMPORTANT factor influencing the rate of evaporative heat loss?

A

relative humidity

42
Q

How does relative humidity influence rate of evaporation?

A

High relative humidity reduces rate of evaporation

43
Q

What is the MOST EFFECTIVE way of cooling under conditions of low humidity

A

evaporation

44
Q

Why does high relative humidity reduce the rate of evaporation?

A

High relative humidity reduces the vapor pressure gradient between skin and environment

45
Q

In order for evaporative cooling to occur during exercise, what must happen to vapor pressure?

A

vapor pressure of skin must be GREATER than VP of air

46
Q

Vapor pressure is influenced by what two things?

A

temperature and relative humidity

47
Q

At any given air temperature, what is the relationship between RH and VP?

A

a rise in RH results in increased VP in the air

48
Q

T/F: less evaporative cooling occurs on a hot/humid day when compared to cool/low humidity day

A

True

49
Q

How much heat be lost via evaporation during exercise?

A
  • The body loses 0.58 kcal of heat for each ml of water that evaporates.
  • Evaporation of 1 L of sweat would result in a heat loss of 580 kcal
50
Q

Most heat loss during exercise in a cool/moderate environment occurs due to what?

A

Evaporation

51
Q

Where is storage unit for any heat that is produced by working muscles during exercise and is NOT lost?

A

body tissues

52
Q

How is the amount of heat gain in body during exercise computed?

A

body heat gain during exercise: (heat produced - heat loss)

53
Q

The amount of heat energy required to raise body temperature depends upon what two things?

A

size of individual and characteristic of body tissue (specific heat)

54
Q

What is specific heat? and what is the SH for the human body per kg of body mass?

A

amount of heat energy required to raise 1 kg of body tissue by 1 C; 0.83 kcal

55
Q

What is the equation for the amount of heat required to elevate the body temp by 1C?

A

heat required to increase body temperature by 1C= (SH x BM)

56
Q

What is the set point temperature in humans?

A

37 C

57
Q

Input to temperature regulating centers in the POAH comes from

A

both skin and core

58
Q

Changes in environmental temperature are first detected what kind of receptors? and then comes

A
  • thermal receptors located in skin
  • they transmit nerve impulses to the POAH which then initiates the appropriate response in an effort to maintain the body’s set point temperature
59
Q

What happens when there is an increase in core temperature above the set point?

A
  • hypothalamus initiating a series of physiological actions
  • First, hypothalamus stimulates sweat glands which results in an increase in evaporative heat loss
  • vasomotor control center withdraws the normal vasoconstrictor tone to the skin promoting cutaneous vasodilation and increased skin blood flow and therefore allowing increased heat loss
  • When core temperature returns to normal, the stimulus to promote both sweating and vasodilation is removed
60
Q

When cold receptors are stimulated in the skin, what acts to minimize heat loss and increase heat production?

A

thermoregulatory control center

61
Q

To prevent further loss of heat, what steps do the body take?

A
  • First, vasomotor center directs peripheral blood vessels to vasoconstrictor, which reduces heat loss
  • if core temperature drops significantly, involuntary shivering begins
  • additional responses include stimulation of pilomotor center (goosebumps)
  • POAH increases thyroxine production and release which increases cellular heat production
  • POAH initiates the release of NE which increases cellular metabolism (nonshivering thermogenesis)
62
Q

What is a fever?

A

an increase in body temperature above the normal range, caused by numerous bacterial/viral infections or brain disorders

63
Q

During a fever, what causes set point of body thermostat to rise above normal level?

A

Pyrogen

64
Q

Cold exposure results in POAH promoting physiological changes that increase body heat by:

A

increasing body heat production (shivering) and reducing heat loss (cutaneous vasoconstriction)

65
Q

Explanation of how thermal events that occur during submaximal constant load exercise in cool/moderate environment

A
  • heat production increases during exercise due to muscular contraction
  • venous blood draining the exercising muscle distributes excess heat throughout the body core
  • As core temperature increases, thermal sensors in POAH sense increase in blood temp and thermal integration center in POAH compares this increase in temp with set point temperatures and finds difference between two
  • the response is to direct the NS to initiate sweating and to increase blood flow to the skin
  • these acts serve to increase bod heat loss an minimize the increase in body temp
  • at this point the internal temperature reaches a new, elevated steady state level
66
Q

Roles of evaporation, convection, and radiation in heat loss during constant load exercise in moderate environment

A
  • constant but small role of convection and radiation in heat loss (bc constant temp gradient between skin and room)
  • Evaporation plays the MOST IMPORTANT role in heat loss during exercise in cool and low humidity environment
67
Q

During constant intensity exercise, core temperature increase is directly related to what? and independent of what?

A

Directly related to exercise intensity; independent of ambient temperature over a wide range of conditions

68
Q

What determines the rise in core temperature during exercise? and what does this suggest?

A

exercise intensity and not environmental temperature; which suggests that the method of heat loss during continuous exercise is modified according to ambient conditions

69
Q

As ambient temperature increases, what happens to the rate of convective and radiative heat loss; how is evaporation impacted?

A
  • the rate of convective and radiative heat loss decreases due to a decrease in skin to room temperature gradient
  • increase in evaporative heat loss which allows core temperature to remain the same
70
Q

What is the relationship between exercise intensity and body heat production?

A
  • There is a linear increase in energy output, heat production, and total heat loss as a function of exercise work rate
  • convective and radiative heat loss are not increased as a function of exercise work rate
  • there is a consistent rise in evaporative heat loss with increments in exercise intensity
71
Q

what is the PRIMARY MEANS of losing heat during exercise in most environmental conditions?

A

Evaporation

72
Q

body heat production increases in proportion to what?

A

exercise intensity

73
Q

What is Heat Index?

A
  • typically expressed in degrees F or Centigrade and is a measure of how hot it feels when relative humidity is added to actual air temperature
  • measure of body’s perception of how hot it feels
74
Q

How is Heat Index calculated?

A

combining the air temperature and relative humidity to compute an apparent temperature

75
Q

T/F high humidity decreases an individual’s perception of how hot the environment feels?

A

False; increases

76
Q

High heat and humidity reduces the body’s ability to what?

A

lose heat by radiation/convection and evaporation

77
Q

What is hyperthermia?

A

large rise in core temperature

78
Q

What increases the risk of hyperthermia?

A

combined effect of fluid loss and high core temperature

79
Q

In an effort to increase evaporative heat loss during exercise humans rely on what?

A

ability to increase sweat production via eccrine sweat glands

80
Q

Explain how sweat rates vary widely across different individuals?

A
  • heat accustomed individuals have an earlier onset of sweating and higher sweat rate during exercise
  • large individuals will have likely higher sweat rates compared to smaller individuals
  • genetic variations in sweat rates exist such that two individuals with same body size and level of heat adaptation may also differ in sweat rates
81
Q

Why do American football players experience the highest sweat rates ever recorded for athletes?

A
  • many football players possess large body masses and that football uniforms retard heat loss
82
Q

What are the three major factors that contribute to impaired exercise performance in the heat?

A
  1. accelerated muscle fatigue
  2. cardiovascular dysfunction
  3. central nervous system dysfunction
83
Q

How to prevent overheating during exercise?

A
  1. exercise during coolest part of the day
  2. minimize both the intensity and duration of exercise on hot/humid days
  3. expose a maximal surface area of skin for evaporation during exercise
  4. when removal of clothing during exercise is not possible provide frequent rest/cool breaks along with intermittent clothing shed
  5. avoid dehydration during exercise
  6. rest/cool down breaks during exercise should remove the athlete from radiant heat gain due to direct sunlight
  7. measure body weight at the beginning and end of training session to determine the amount of fluid replacement required to restore body water balance before next training session
84
Q

During exercise in a hot environment three major changes occur muscle metabolism that contribute to muscle fatigue:

A
  1. rate of muscle glycogen breakdown is creased
  2. exercise in hot environment increases muscle lactate production and this exercise induced increase in muscle lactate levels results in decreased muscle pH
  3. during exercise in a hot environment, skeletal muscle production of free radicals is increased
85
Q

Why is increase in free radicals significant?

A
  • increased production of free radicals in muscles can also contribute to muscle fatigue
  • radicals are highly reactive molecules that contain an unpaired electron in their outer orbital
  • free radicals rapidly react with muscle proteins resulting in oxidative damage
  • this heat induced increase in muscle radical production can damage contractile proteins resulting in reduced muscle for production (muscle fatigue)

Exercise Physiology (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions