Deck 10: Physical Activity- Thermoregulation

Question 1

Heat loss occurs by these two physical mechanisms.

A) Radiation and convection
B) Radiation and conduction
C) Radiation, conduction, convection, and evaporation
D) Conduction and convection

Answer 1

Radiation, conduction, convection, and evaporation

Question 2

Provides the major physiologic defense against overheating.

A) Evaporation
B) Radiation
C) Conduction
D) Convection

Answer 2

Evaporation

Question 3

Contains the central coordinating center for temperature regulation.

A) Brainstem
B) Medulla oblongata
C) Pons
D) Hypothalamus

Answer 3

Hypothalamus

Question 4

During physical activity in hot weather, competition exists between mechanisms that __________.

A) regulate body temperature and mechanisms that regulate urine production
B) maintain a large muscle blood flow and mechanisms that regulate fat metabolism
C) maintain a large muscle blood flow and mechanisms that regulate body temperature
D) regulate body temperature and mechanisms that regulate fat metabolism

Question 5

Body heat loss that occurs via electromagnetic heat waves.

A) Radiation
B) Conduction
C) Convection
D) Evaporation

Question 6

Sweat evaporation from the skin depends on three factors.

A) Skin exposed to the environment, temperature and relative humidity, and convective air currents
B) Skin exposed to the environment, temperature and relative humidity, and hydration level
C) Skin exposed to the environment, hydration level, and convective air currents
D) Hydration level, temperature and relative humidity, and convective air currents

Question 7

Refers to the percentage of water in ambient air at a particular temperature compared to the total quantity of moisture that the air could carry.

A) Dew point
B) Relative humidity
C) Moisture index
D) Heat index

Question 8

Hormone that increases water reabsorption from the kidney tubules causing urine to become more concentrated.

A) Cortisol
B) Insulin
C) Glucagon
D) ADH

Question 9

Hormone that decreases sodium concentration in sweat, which aids in electrolyte conservation.

A) Aldosterone
B) ADH
C) ACTH
D) Thyroxin

Question 10

__________ fabrics worn close to the skin provide optimal transfer of heat and moisture from the skin to the environment.

A) Nylon
B) Cotton
C) Polyester
D) Moisture-wicking

Question 11

Several hours of intense sweating can cause __________ fatigue, which ultimately impairs core temperature regulation.

A) hormonal
B) heat generating
C) central nervous system
D) sweat gland

Question 12

Does not associate with progressive dehydration.

A) Decreased plasma volume
B) Increased blood flow to active muscles
C) Diminished sweating rate
D) Diminished peripheral blood flow

Question 13

The risk for dehydration __________ during vigorous cold-weather physical activity.

A) increases
B) decreases dramatically
C) is eliminated
D) decreases slightly

Question 14

Cold stress __________ urine production, which adds to total body fluid loss.

A) increases
B) dramatically decreases
C) eliminates
D) slightly decreases

Question 15

Not associated with creating a distinct performance disadvantage for athletes who use diuretics to lose body water to rapidly "make weight"?

A) Disproportionate reduction in plasma volume
B) Decreased thermoregulatory capabilities
C) Increased hematocrit
D) Impaired cardiovascular function

Question 16

Athletes who use __________ to lose weight not only produce dehydration but also cause excessive mineral loss associated with muscle weakness and impaired neuromuscular function.

A) vomiting and diarrhea
B) saunas
C) long runs
D) plastic clothing

Question 17

Not a benefit associated with hyperhydration to help protect the athlete against heat stress before exercising in a hot environment?

A) Delays dehydration
B) Increases sweating during physical activity
C) Dilutes electrolytes in extracellular fluid
D) Inhibits the rise in core temperature

Question 18

Pre-exercise hyperhydration __________ the need to continually replace fluid during physical activity.

A) does not replace
B) eliminates
C) dramatically reduces
D) increases

Question 19

Not a urine characteristic of well-hydrated individuals?

A) Large volume
B) Deep yellow-orange in color
C) Light in color
D) Lacks a strong smell

Question 20

Dehydration as little as __________ of total body mass impairs physical work capacity and physiologic function.

A) 2%
B) 10%
C) 15%
D) 20%

Question 21

Sweat gland classification.

A) Apocrine
B) Eccrine
C) Endocrine
D) Exocrine

Question 22

Osmolality of sweat considered __________ in relation to other body fluids.

A) isotonic
B) iso-osmotic
C) hypotonic
D) hypertonic

Question 23

The hypothalamus.

A) Receives input from receptors in the blood sensitive to changes in PO₂
B) Acts as a "thermostat" for temperature regulation
C) Is a thermoregulatory organ that functions only during strenuous physical activity
D) Receives input from the blood relative to PCO₂ changes

Question 24

Provides "fine tuning" for temperature regulation.

A) Hormonal adjustments
B) PH adjustments
C) Circulatory adjustments
D) Pulmonary adjustments

Question 25

Full acclimatization generally occurs within about __________ days of heat exposure.

A) 2
B) 5
C) 10
D) 20

Question 26

Football uniforms effectively seal off about __________ of the body's surface from the benefits of evaporative cooling.

A) 20%
B) 35%
C) 50%
D) 65%

Question 27

The most serious and complex heat-stress malady and requires immediate medical attention.

A) Heat intolerance
B) Exertional heat stroke
C) Heat cramps
D) Heat exhaustion

Question 28

Excess __________ has a negative effect on performance in hot environments.

A) muscle mass
B) hydration
C) body fluid
D) body fat

Question 29

Sweating is the body's defense against __________. The effect of __________ enables moisture to __________ the body.

A) overheating, radiation, cool
B) thermoregulation, conduction, warm
C) thermoregulation, convection, warm
D) overheating, evaporation, cool

Question 30

Which statement is true concerning thermoregulation and gender?

A) Women are at least as efficient as men in thermoregulation during physical activity when considering level of fitness and acclimatization.
B) Men tend to produce less sweat than women while maintaining the same core temperature.
C) Men possess more heat-activated sweat glands per unit skin area than women.
D) Men rely more on circulatory mechanisms for heat dissipation.

Question 31

The wet-bulb globe temperature index make use of __________ to evaluate environmental heat challenges.

A) cold weather comparisons
B) altitude
C) relative humidity
D) water evaporation

Question 32

Heat acclimatization.

A) Reduces the distribution of blood flow to the skin
B) Increases sweating capacity
C) Produces more concentrated sweat
D) Decreases sweating volume

Question 33

Fluid loss as little as __________ of body mass increases rectal temperature compared to exercising in the heat without fluid loss.

A) 1%
B) 3%
C) 5%
D) 7%

Question 34

Occurs when body temperature increases by 5°C or more.

A) Hyponatremia
B) Hypernatremia
C) Hypothermia
D) Hyperthermia

Question 35

The most important performance-enhancing nutrient when physical activity and heat stress combine.

A) Water
B) Sodium
C) Glycogen
D) Protein

Question 36

An important avenue for heat loss during physical activity-induced hyperthermia.

A) Head
B) Neck
C) Hands
D) Feet

Question 37

During sustained physical activity by aerobically fit men and women, metabolic rate often increases __________ times above the resting level.

A) 10 to 15
B) 20 to 25
C) 30 to 35
D) 40 to 45

Question 38

The most common heat illness among physically active people.

A) Heat exhaustion
B) Heat cramps
C) Heat flush
D) Heat stroke

Question 39

Cells that play the most important role in initiating regulatory responses to cold environments?

A) Hair follicle cells
B) Cutaneous heat receptors
C) Cutaneous cold receptors
D) Deep tissue nerve receptors

Question 40

Increased ambient temperature __________ the effectiveness of heat loss by conduction, convection, and radiation.

A) supports
B) has no effect on
C) increases
D) reduces

Question 41

Which of the following statements regarding relative humidity and heat loss is true?

A) Continually drying the skin with a towel before sweat evaporates enhances evaporative cooling.
B) One can tolerate relatively high environmental temperatures as long as humidity remains low.
C) Sweat cools the skin more effectively in high temperatures with high humidity.
D) With high humidity, ambient air's vapor pressure approaches that of moist skin, which enhances evaporative heat loss.

Question 42

Serves as the "workhorse" to maintain thermal balance.

A) Pulmonary
B) Neurologic
C) Circulatory
D) Renal

Question 43

Represents the best clothing choice for participating in physical activity in hot temperatures?

A) Dark-colored, moisture-wicking clothing
B) Dark-colored, cotton clothing
C) Light-colored, moisture-wicking clothing
D) Light-colored, cotton clothing

Question 44

Fluid lost during thermoregulation often creates a relative state of __________.

A) dehydration
B) hypothermia
C) hypernatremia
D) hypoglycemia

Question 45

Regarding core temperature during physical activity?

A) Heat generated by active muscles can decrease shell temperature to hypothermic levels.
B) A significant rise in shell temperature reflects a favorable internal adjustment.
C) A well-regulated rise in core temperature occurs even during physical activity in the cold.
D) An increased core temperature with physical activity reflects a failure of heat-dissipating mechanisms.

Question 46

An imbalance in fluid dynamics when fluid intake does not replenish water loss.

A) Water intoxication
B) Hyponatremia
C) Hyperhydration
D) Dehydration

Question 47

A moderate workout generally produces a __________ sweat loss over a 1-hour period.

A) 0.5- to 1.5-liter
B) 2- to 4-liter
C) 0.5- to 1.5-milliliter
D) 2- to 4-milliliter

Question 48

Body fluid loss coincides with which of the following?

A) Increased stroke volume
B) Decreased plasma volume
C) Decreased heart rate
D) All of the above

Question 49

Hyperhydration before physical activity in a hot environment protects against heat stress because it fosters the following.

A) Increases sweat osmolality
B) Decreases skin temperature
C) More rapidly restores lost plasma volume
D) Delays dehydration

Question 50

With prolonged physical activity in the heat, sweat loss can deplete the body of this much sodium.

A) 13 to 17 grams
B) 20 to 25 grams
C) 26 to 30 grams
D) 35 to 40 grams

Question 51

Which of the following minerals has the greatest need for replenishment after heavy sweating?

A) Potassium
B) Sodium
C) Magnesium
D) Calcium

Question 52

Exists when the serum sodium concentration falls below 135 mEq/L.

A) Hypernatremia
B) Dehydration
C) Hyponatremia
D) Hypokalemia

Question 53

Should be done to reduce risk of overhydration and hyponatremia during prolonged physical activity?

A) Drink 400 to 600 milliliters of fluid 2 to 3 hours before physical activity.
B) About 30 minutes before physical activity, drink 1500 to 3000 milliliters of fluid.
C) Restrict salt in the diet.
D) Drink more than 1000 mL·h^-1 of plain water.

Question 54

Aging blunts the magnitude of the sweating response by __________.

A) increasing sweat gland output
B) causing the onset of sweating to occur sooner
C) modifying thermoreceptors sensitivity
D) greater vasodilation of skin receptors

Question 55

Elevation in core body temperature causes __________.

A) increased gastric emptying rate
B) reduced stomach and intestinal motility
C) increased efficiency of digestion
D) no change in efficiency of digestion

Question 56

The use of a cycling helmet is __________ because __________.

A) not recommended, wearing a helmet causes actual heat strain in riders
B) not recommended, wearing a helmet causes perceived and actual heat strain in riders
C) recommended, wearing a cycling helmet protects the head from injury and does not cause heat strain
D) not recommended, wearing a helmet impairs performance and causes heat strain that outweigh any safety benefits

Question 57

From a practical standpoint, __________ exposed to environmental heat stress should exercise at reduced intensity and receive more time to acclimatize than __________.

A) children, mature adults
B) mature adults, children
C) men, women
D) child athletes, sedentary children

Question 58

Development of hypernatremia requires extreme sodium loss through prolonged sweating coupled with dilution of existing extracellular sodium.

Question 59

Children exposed to environmental heat stress should exercise at reduced intensity and receive more time to acclimatize than more mature competitors.

Question 60

Radiation is a form of heat transfer that does not require molecular contact between objects.

Question 61

Skin cooling occurs only when sweat evaporates.

Question 62

Men possess more heat-activated sweat glands per area of skin area than women.

Question 63

The endocrine system represents the "workhorse" for temperature regulation.

Question 64

Aldosterone facilitates sodium absorption by the small intestine.

Question 65

Heat acclimatization refers to the physiologic adaptations to improve heat tolerance.

Question 66

Full heat acclimatization cannot take place without exposure to environmental heat stress.

Question 67

Excess body fat decreases metabolic cost of weight-bearing activities and increases effective heat exchange.

Question 68

Factors other than air temperature that determine the physiologic strain imposed by heat include body size and fatness, level of training, acclimatization, adequacy of hydration, and external factors.

Question 69

Wet-bulb temperature is the air temperature in the shade recorded by a mercury thermometer.

Question 70

Heat cramps, or involuntary muscle spasms, occur during or after intense physical activity, usually in the specific muscles exercised.

Question 71

Whole-body cold or ice water immersion is not an effective treatment for a collapsed hyperthermic individual.

Question 72

Core temperature rises quickly when heat gain exceeds heat loss during vigorous physical activity in a warm environment.

Question 73

The pituitary gland contains the central coordinating center for temperature regulation.

Question 74

The body's thermoregulatory mechanisms primarily protect against overheating.

Question 75

The rate of conductive heat loss depends on the temperature gradient between the skin and surrounding surfaces and their thermal qualities.

Question 76

The effectiveness of heat loss by evaporation via air depends on how rapidly air near the body exchanges once it warms.

Question 77

Sweating rate increases directly with increases in ambient temperature.

Question 78

Relative humidity has no impact on the effectiveness of evaporative heat loss.

Question 79

Dehydration refers to an imbalance in fluid dynamics when fluid intake does not replenish water loss from either hyperhydrated or normally hydrated states.

Question 80

Sweat is hypertonic compared with other body fluids.