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Exercise Physiology > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Efficiency of human body to perform physical work

A

≈15-30% (slightly higher @ rest ≈34%)

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2
Q

Remaining 70-85% of expended energy converted to…?

A

heat

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3
Q

Typical resting core temp.

A

≈ 37 degrees C (98.6 degrees F)

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4
Q

Humans either retain or dissipate heat based upon…?

A

how close core temp. is to your typical resting level

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5
Q

The neuro-endrocrine organ responsible for maintaining core temp. as close to 37 C as possible

A

Hypothalamus

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6
Q

Temp. regulation centers collectively function as a bi-directional thermostat & are situated on:

A

hyperthermia: anterior aspect of hypothalamus
hypothermia: posterior aspect of hypothalamus

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7
Q

Other functions of hypothalamus:

A

water balance

sugar & fat catabolism

satiety (hunger) center

controls other endocrine glands

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8
Q

When the core temp. ___________ is interrupted, the temp. center w/in hypothalamus activates several mechanisms which attempt to return the core temp. to normal

A

homeostasis

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9
Q

Core temp. too low, it’s increased by…?

A
  1. heat conservation

2. increased heat production

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10
Q

Heat conservation initiated via:

A
  • decreased sweat rate

- decreased blood flow to extremities & to skin’s surface (DERMAL VASOCONSTRICTION)

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11
Q

Heat production initiated via:

A
  • SHIVERING
    (SNS increases catabolic rate 2-4 times resting level)
  • hypothalamus may trigger THYROID GLAND TO RELEASE THYROXIN which increases catabolic rate
  • hypothalamus may trigger ADRENAL MEDULLA TO RELEASE CATECHOLAMINES (EPINEPHRINE & NOREPINEPHRINE) which also increase catabolic rate
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12
Q

When core temp is too high, it’s decreased by…?

A
  1. Heat dissipation

2. Decreased heat production (possible in resting state)

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13
Q

Heat dissipation initiated via 2 precursors:

A
  • Increased sweat rate

- Increased blood flow to extremities & skin surface (DERMAL VASODILATION)

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14
Q

After one or both precursors have been initiated, one or more of the following processes may contribute to the dissipation of excess heat via:

A
  • Conduction
  • Convection
  • Radiation
  • Evaporation
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15
Q

After dermal vasodilation: CONDUCTION

A

Transfer of heat energy via DIRECT SURFACE CONTACT from hotter to cooler surface

-absorption vs. dissipation

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16
Q

Temperature gradient

A

transfer of heat energy from hotter to cooler surface temperature

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17
Q

After dermal vasodilation:

CONVECTION

A

subsequent to transfer of heat to a gas or liquid, the heated substance rises (temperature gradient) — gas Vs. liquid - absorption Vs. dissipation

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18
Q

After dermal vasodilation: RADIATION

A

transfer of heat via electromagnetic waves

(temperature gradient required) - absorption Vs. dissipation

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19
Q

After increased sweat rate:

EVAPORATION

A
  • each gram of vaporized water dissipates ~ .58 kcal of heat energy
  • called the energy of vaporization OR heat of vaporization
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20
Q

Do dermal vasodilation & perspiration dissipate heat?

A

Dermal vasodilation & perspiration do NOT dissipate heat, but one or both are necessary precursors to heat loss.

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21
Q

Consider these for temperature regulation:

A
  • artificial environments (clothes, rooms)
  • effects of ethyl alcohol

hot vs. cold considerations

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22
Q

Effects of ethyl alcohol:

A
  • dermal vasodilation
  • diuretic
  • depressant
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23
Q

Decreased heat production initiated via:

A

-Decreased metabolic rate: slowing down or ceasing some physiological functions

(obviously, a person would have to stop exercising in this case)

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24
Q

Do anatomic &/or physiological differences between males and females make a difference in the responses to hot/humid ambient conditions?

A

Yes; but they are not understood

25
Q

Who has more sweat glands; males or females?

A

Females;
Regardless, females sweat less than males (generally speaking) likely as a result of gender differences in selected hormone levels

26
Q

Who has more body fat; males or females?

A

Females typically have ~ 10% more body fat:

  • much distributed in the subcutaneous region
  • fat serves as an insulator
  • greater amounts of subcutaneous fat result in less angular surface area, so less surface area/unit of body mass exists
27
Q

Who has lower VO2 max; males or females?

A
  • females frequently have lower VO2 max when expressed in absolute or relative terms
  • the lower the VO2 max , the lower the efficiency of heat-dissipation mechanisms
28
Q

Males/females typically respond to elevated core temps. w/ greater dermal vasodilation?

A

Females

29
Q

Generally speaking about dissipating heat, which gender relies mainly on EVAPORATION, CONDUCTION, RADIATION, & CONVECTION?

A
  • MEN RELY ON EVAPORATION more than females do

- FEMALES RELY ON CONDUCTION, CONVECTION, & RADIATION more than males do

30
Q

Well-conditioned individuals will be at least partially heat acclimated & so will sweat sooner in response to high core temps. as well as sweat more at any point in time: T or F?

A

True

31
Q

Do conditioning levels contribute to a person’s ability to respond to heat stress?

A

yes

32
Q

Dermal vasodilation proportionally lowers the quantity of blood available to ____ ____ during ___?

The elevated sweat rate in males reduces overall blood volume resulting in a similar net effect unless fluids are restored in a timely manner.

A

SKELETAL MUSCLES during EXERCISE

33
Q

Males tend to have an advantage in ___, ___ ambient conditions

A

hot, dry

34
Q

Females tend to have an advantage in ___, ___ ambient conditions

A

warm, humid

35
Q

Dehydration/hypohydration is a condition in which…?

A

body fluids have been excessively lost via sweating, respiration, blood loss, &/or urinary/GI excretion

36
Q

Dehydration results in an increase in plasma ___ & ___ concentrations due to a substantial loss of plasma water.

A

protein & electrolyte

37
Q

A decrease in total blood vol. results in a decreased ___ ___?

A

stroke volume (SV)

38
Q

In order to maintain cardiac output (Q) during submaximal exercise, heart rate (HR) must be ___ when compared to a euhydrated state?

A

increased

39
Q

Dehydration also results in a ___ maximal cardiac output?

A

decreased

Q= HR x SV

40
Q
  1. The potential for heat dissipation via conduction, convection, and radiation is reduced by a decrease in total blood volume which results in decreased ___ ___ ___?
  2. Which also results in an ___ core temp?
A
  1. Peripheral blood flow

2. elevated

41
Q

What percentage of a decrease in body weight via dehydration will reduce physical work capacity & local muscular endurance?

A

5%

42
Q

Is strength affected by dehydration?

A

not really, except extreme cases

43
Q

1 lb of body weight from fluid losses = ? (how much water)

A

a pint

44
Q

Is thirst a good indicator of fluid needs during exercise?

A

no

45
Q

Heat acclimatization is characterized by individuals

A
  • sweating at lower core temps.
  • sweating more at all elevated core temps.
  • hypotonic sweat
46
Q

Heat acclimated people will:

A
  • store less heat during the initial phases of exercise

- will reach a lower thermal steady state

47
Q

Less dermal blood flow and the availability of more cardiac output for active tissues is caused by ____ ___ ___ ___ ____?

A

cooler core and skin temps.

48
Q

If cooler core and skin temps are due to sweat loss, blood volume decreases which means ____ ____ _____.

A

less cardiac output

49
Q

What is albumin?

A

blood borne protein

most abundant protein found in blood

50
Q

During heat acclimatization, degradation of _____ is reduced & production by the liver is at least maintained.

A

albumin

51
Q

This results in an ______ in the amount of albumin that is circulating.

A

increase

52
Q

Albumin binds with fluid.

Each gram of albumin binds with how much blood plasma?

A

13 ml

53
Q

Albumin binds with ___ ___ ___s and various hormones.

A

free fatty acids (FFA)

54
Q

A fully heat acclimated person will have retained about ____% more plasma than the non-acclimated person because of _____ albumin levels.

A

20%

increased

  • B/c a greater fluid reserve exists for sweating and the maintenance of SV and Q
55
Q

This blood adaptation is normally completed within ___ weeks.

A

2

56
Q

A well-trained individual may be about ___% heat acclimated even when conditioning occurs in a cool environment.

A

about 50%

adaptation takes about 1 week

57
Q

Training activities typically result in ___ core temps, and in turn, will partially acclimate the person to high thermal conditions.

A

elevated

58
Q

Performing activities that mainly involve the ___ system will be compromised when ambient conditions are hot/humid, especially if noticeable heat acclimatization is lacking.

A

CR system

Exercise Physiology (6 decks)

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