Chapter 12 Temperature Regulation Exercise Phys

Front 1

An increase in body temperature above __C may destroy protein structure of enzymes and a decrease in body temperature below ___ C may cause a slowed metabolism and abnormal cardiac function.

Back 1

45
34

Front 2

Animals that maintain a rather constant body core temperature are called ____________. The maintainence of a constant body temperature requires that heat loss must match the rate of heat production.

Back 2

homeotherms

Front 3

The body is set near the ____ end of the survival range and is held constant by continuous metabolic heat production coupled with a small but continual heat loss.

Back 3

high

Front 4

One of the most important functions of the circulatory system is to transport ____. Blood is very effective in this function because it has a high capacity to store heat.

Back 4

heat

Front 5

There is a _________ between deep-body temperature areas and the shell temperature. The ideal difference between core and skin temperatures is 4 C.

Back 5

gradient

Front 6

Measurements of deep-body temperatures can be accomplished with _________ thermometers or with devices known as thermocouples or thermistors.

Back 6

mercury

Front 7

_______ temperature can be used to estimate changes in deep-body temperature during exercise. In addition temperature measurements near the eardrum (called tympanic temperature) have been found to be a good estimate of brain temperature.

Back 7

Rectal

Front 8

In a field setting, what types of thermometers are used to determine deep body temperature?

Back 8

Ingestible temperature sensors

Front 9

The _____ skin temperature can be calculated by assigning certain factors to each individual skin measurement in proportion to the body's total surface area that each measurement represents.

Back 9

mean

Front 10

The temperature control center is an area in the brain called the ____________, which works as a thermostat by iniating an increase in heat production when body temperature falls and an increase in the rate of heat loss when body temperature rises.

Back 10

hypothalamus

Front 11

Heat production can be classified as _________ (exercise) or __________ (shivering or biochemical heat production caused by the secretion of hormones such as thyroxine and catecholamines)

Back 11

voluntary
involuntary

Front 12

Involuntary heat production by shivering is the primary means of increasing heat production during exposure to cold. The release of ________ from the thyroid gland can also increase metabolic rate of all cells in the body. An increase in blood levels of catecholamines ( ___________ and ____________) can cause an increase in the rate of cellular metabolism.

Back 12

thyroxine
epinephrine
norepinephrine

Front 13

The increase in heat production due to the combined influences of thyroxine and catecholamines is called ____________ _______________.

Back 13

nonshivering thermogenesis

Front 14

_________ is heat loss in the form of infared rays. This involves the transfer of heat from the surface of one object to the surface of another, with no physical contact being involved.

Back 14

Radiation

Front 15

Radiation accounts for ___% of heat loss from the body at rest in a comfortable environment. This is possible because skin temperature is greater than the temperature of surrounding objects (walls, floor, etc.) and a net loss of body heat occurs due to the thermal gradient.

Back 15

60

Front 16

__________ is defined as the transfer of heat from the body into the molecules of cooler objects in contact with its surface. In general, the body only loses small amounts of heat due to this process.

Back 16

Conduction

Front 17

_________ is a form of conductive heat loss in which heat is transmitted to either air or water molecules in contact with the body. Air or water molecules are warmed and move away from the source of heat and are replaced by cooler molecules.

Back 17

Convection

Front 18

An example of ______ convection is a fan moving large quantities of air past the skin; this would increase the number of air molecules coming in contact with the skin and thus promote heat loss.

Back 18

forced

Front 19

Cycling at high speeds or swimming in cool water would result in what type of heat loss?

Back 19

Convective

Front 20

In ________, heat is transferred from the body to water on the surface of the skin. When this water gains sufficient heat (energy), it is converted to a gas (water vapor), taking the heat away from the body. This occurs due to a vapor pressure gradient between skin and the air.

Back 20

Evaporation

Front 21

Evaporation accounts for approximately ___% of the heat loss at rest, but under most environmental conditions it is the most important means of heat loss during exercise.

Back 21

25

Front 22

Evaporative cooling during exercise occurs in the following way. When body temperature rises above normal, the _______ ________ stimulates sweat glands to secrete sweat onto the surface of the skin. As sweat evaporates, heat is lost to the environment, which in turn lowers skin temperature.

Back 22

nervous system

Front 23

Evaporation of sweat from the skin is dependent on which of the following?
a. the temperature and relative humidity
b. the convective currents around the body
c. the amount of skin surgace exposed to the environment
d. all of the above
e. none of the above

Back 23

d. all of the above

Front 24

When the relative humidity is near 100% evaporation is ________.

Back 24

limited

Front 25

High relative _______ reduces the vapor pressure gradient between the skin and the environment. On a hot, humid day the vapor pressure in the air is close to the vapor pressure on moist skin.

Back 25

humidity

Front 26

Evaporation of 1 L of sweat would result in a heat loss of ____ kcal.

Back 26

580

Front 27

Any heat that is produced by the working muscles during exercise and is not lost, must be stored by the _____ ______.

Back 27

body tissues

Front 28

The term ________ _____ refers to the amount of heat energy required to raise 1 kg of body tissue by 1 C. The specific heat for the human body is 0.83 kcal per kilogram of body mass.

Back 28

specific heat

Front 29

The _______ hypothalamus is primarily responsible for dealing with increases in body heat.

Back 29

anterior

Front 30

The ________ hypothalamus is responsible for reacting to a decrease in body temperature.

Back 30

posterior

Front 31

The hypothalamus tries to maintain a set point temperature around ___ C

Back 31

37

Front 32

The input to temperature regulating centers in the hypothalamus comes from receptors in both the _____ and the _____.

Back 32

skin
core

Front 33

Changes in environmental temperature are first detected by _______ receptors on the skin. The skin temperature receptors transmit nerve impulses to the hypothalamus, which then initiates the appropriate response in an effort to maintain the body's set-point temperature.

Back 33

thermal

Front 34

Heat-/cold-sensitive ______ are located in both the spinal cord and the hypothalamus itself, sensing changes in the core temperature.

Back 34

neurons

Front 35

In response to an increase in core temperature, the hypothalamus stimulates the sweat glands, which results in what type of heat loss? In addition, the vasomotor control center withdraws the normal vasoconstrictor tone to the skin, promosting (decreased/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.

Back 35

evaporative heat loss
increased

Front 36

When cold receptors are stimulated in the skin or the hypothalamus, the thermoregulatory control center sets forth a plan of action to minimize heat loss. The vasomotor control center directs peripheral blood vessels to _____________, which promotes heat loss. If core temperature drops significantly, involuntary ________ begins. Additional responses include stimulation of the pilomotor center, which promotes piloerection (_________).

Back 36

vasoconstrict
shivering
goosebumps

Front 37

The hypothalamus also indirectly increases ________ production and release, which increases cellular heat production. The posterior hypothalamus also initiates the release of ____________, which increases the rate of cellular metabolism.

Back 37

thyroxine
norepinephrine

Front 38

During a fever, certain proteins and other toxins secreted by bacteria can cause the set point of the hypothalamic thermostat to rise above the normal level. Substances that cause this effect are called ______.

Back 38

pyrogens

Front 39

Heat production increases during exercise due to muscular contraction and is (indirectly/directly) proportional to the exercise intensity. The venous blood draining the exercising muscle distributes the excess heat throughout the body core.

Back 39

directly

Front 40

Once the hypothalamus regulates body temperature to promote heat loss, it reaches a new, elevated ______-______ level.

Back 40

steady state

Front 41

During constant load exercise, the core temperature is (indirectly/directly) related to exercise intensity.

Back 41

directly

Front 42

The _____ ______ is typically expressed in degrees Farenheit and is a measure of how hot it feels when relative humidity id added to the actual air temperature.

Back 42

Heat Index

Front 43

The combined effect of fluid loss and high core temperature increases the risk of ___________ (large rise in core temperature) and heat injury

Back 43

hyperthermia

Front 44

In an effort to increase evaporative heat loss during exercise, humans rely on their ability to increase sweat production via ______ sweat glands.

Back 44

eccrine

Front 45

True/False Heat acclimitized individuals have an earlier onset of sweating and a higher sweat rate during exercise.

Back 45

True

Front 46

The general symptoms of ____ _______include nausea, headache, dizziness, reduced sweat rate, and the general inability to think rationally.

Back 46

heat stress

Front 47

When an athlete develops symptoms of heat injury, the obvious treatment is to stop exercising and immediately begin cooling the body. Cold fluids with ___________ should also be provided for rehydration.

Back 47

electrolytes

Front 48

Hyperthermia can directly diminish exercise performance due to central nervous system impairment to reduce the mental drive for ______ performance.

Back 48

motor

Front 49

Research indicates that muscle blood flow is reduced during prolonged exercise in a hot environment. Reduction in MM blood flow during exercise in heat occurs due to a competition for ____ between working muscles and the skin. Blood flow moves away from MM and toward skin to assist in cooling.

Back 49

blood

Front 50

True/False Work in the cold results in a more rapid onset of muscular fatigue.

Back 50

False hot

Front 51

Exercise in the heat increases muscle _______ usage and elevates muscle lactate production.

Back 51

glycogen

Front 52

True/False Women are less heat tolerant than men.

Back 52

True

Front 53

__________ and lack of heat ____________in older subjects may describe why some studies show there is a decrease in thermotolerance with age.

Back 53

deconditioning
acclimitazation

Front 54

In order to heat acclimatize, it is recommended to perform strenuous interval training or continuous exercise at an intensity exceeding ___% of the athletes VO2 max in order to promote higher core temperatures.

Back 54

50

Front 55

The primary adaptations that occur are increased ______ volume, an earlier onset of sweating, higher sweat rate, reduced _______ _______ loss in sweat, reduced skin blood flow, increased ______ _____ proteins in tissue.

Back 55

plasma
sodium chloride
heat shock

Front 56

Heat acclimatization is achieved within __-__ days

Back 56

7-14

Front 57

The increase in plasma volume is due to an increase in plasma ______, which maintain central blood volume, stroke volume, and sweating capacity, and allows the body to store more heat with a smaller temperature gain.

Back 57

proteins

Front 58

Heat shock proteins are synthesized with response to ______ and are designed to prevent cellular damage due to heat or other stresses.

Back 58

stress

Front 59

The rate of decay of heat acclimatization is rapid, with reductions in heat tolerance occuring within a few ____ of inactivity. Complete loss of heat tolerance can occur following ___ days of no heat exposure.

Back 59

days
28

Front 60

Exercise in a cold environment enhances an athlete's ability to lose heat and therefore greatly (reduces/increases) the chance of heat injury.

Back 60

reduces

Front 61

The combination of metabolic heat production and warm clothing prevents the development of _________ (large decrease in core temperature) during short-term work on a cold day.

Back 61

hypothermia

Front 62

Hands become numb in cold weather because of the reduction in the rate of ______ transmission and reduced blood flow due to vasoconstriction.

Back 62

neural

Front 63

Cold adaptation results in a reduction in the mean skin temperature at which shivering begins. The explanation for this observation is that cold-acclimatized individuals maintain heat production with less shivering by increasing nonshivering thermogenesis. They increase the secretion of _______________, which results in an increase in metabolic heat production.

Back 63

norepinephrine

Front 64

Cold adjusted individuals can maintain a higher mean ____-and-____ temperature during cold exposure when compared to unacclimatized persons. This is due to improved intermittent peripheral vasodilation to increase blood flow.

Back 64

hand feet

Front 65

Cold adapted people are better able to sleep in cold environments due to elevated level of ___________ ____________.

Back 65

nonshivering thermogenesis

Front 66

If heat loss is less than heat production, there will be
a. a gain in body temperature
b. a loss in body temperature
c. no change in body temperature
d. an initial loss and then a gain in body temperature

Back 66

a. a gain in body temperature

Front 67

During exercise, body temperature is regulated by making adjustments in
a. the amount of heat produced
b. the resting metabolic rate
c. the amount of heat lost
d. biochemical heat production

Back 67

c. the amount of heat lost

Front 68

The temperature control center is in an area of the brain called the
a. medulla
b. pons
c. pituitary
d. hypothalamus

Back 68

d. hypothalamus

Front 69

The amount of energy expended during exercise that appears as heat is approximately
a. 20 to 30%
b. 50%
c. 70 to 80%
d. 100%

Back 69

c. 70 to 80%

Front 70

Hormones released from the thyroid gland are responsible for increasing the metabolic rate. This is called
a. shivering thermogenesis
b. nonshivering thermogenesis
c. chemical thermogenesis
d. insensible heat loss

Back 70

b. nonshivering thermogenesis

Front 71

Radiative heat loss involves
a. heat transfer by air molecules
b. heat transfer by water molecules
c. heat transfer by infrared rays
d. none of the above

Back 71

c. heat transfer by infrared rays

Front 72

Evaporation accounts for approximately ____% of the heat loss at rest.
a. 25
b. 50
c. 75
d. 90

Back 72

a. 25

Front 73

Evaporative cooling would be least effective on a
a. hot, low humidity day
b. hot, high humidity day
c. cold, low humidity day
d. cold, high humidity day

Back 73

b. hot, high humidity day

Front 74

When air temperature is greater than skin temperature, the only means of losing body heat during exercise is via
a. radiation
b. conduction
c. convection
d. evaporation

Back 74

d. evaporation

Front 75

The vasomotor control center is responsible for
a. the sweating response
b. the detection of skin temperature
c. the baroreceptor reflex
d. promoting increased skin blood flow

Back 75

d. promoting increased skin blood flow

Front 76

The rise in core temperature during exercise is most influenced by
a. environmental temperature
b. relative humidity
c. exercise intensity
d. resting metabolic rate

Back 76

c. exercise intensity

Front 77

Which of the following can also be a mechanism of heat gain?
a. radiation
b. convection
c. evaporation
d. none of the above; these are only mechanisms of heat loss

Back 77

a. radiation

Front 78

Which of the following is not an adaptation in heat acclimatization?
a. higher sweat rate
b. delayed onset of sweating
c. higher plasma volume
d. reduction in electrolytes lost in sweat

Back 78

b. delayed onset of sweating

Front 79

Heat acclimatization is almost complete after seven to fourteen days. The adaptations are lost completely within ____ days of no heat.
a. 3
b. 7
c. 14
d. 28

Back 79

d. 28

Front 80

Cold acclimatization results in
a. decrease in nonshivering thermogenesis
b. decreased peripheral circulation
c. improved ability to sleep in the cold
d. all of the above

Back 80

c. improved ability to sleep in the cold

Front 81

Exercise in a cold environment
a. reduces an athlete's ability to lose heat
b. enhances an athlete's ability to lose heat
c. increases the chance of heat injury
d. does both A and C

Back 81

b. enhances an athlete's ability to lose heat

Front 82

The organ(s) that is/are responsible for reacting to increases in core temperature is/are
a. the posterior hypothalamus
b. the thyroid gland
c. the anterior hypothalamus
d. all of the above

Back 82

c. the anterior hypothalamus

Front 83

One reason that females may be less heat tolerant than males is a
a. higher sweat rate in females
b. higher percentage of body fat in females
c. higher plasma volume in females
d. greater skin surface area in females

Back 83

b. higher percentage of body fat in females

Front 84

During submaximal exercise in a cool environment, when mechanism plays the least important role in heat loss?
a. radiation
b. conduction
c. convection
d. evaporation

Back 84

d. evaporation

Front 85

The heat index is calculated by combining air temperature and wind speed and is a measure of the body's perception of how hot it feels.
a. true
b. false

Back 85

b. false