KPE 490 Chapter 10

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

0.5- to 1.5-L

A fluid loss equivalent to as little as ______ of body mass increases rectal temperature above that with the same exercise performed when fully hydrated.

1%

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

10

With prolonged exercise in the heat, sweat loss can deplete the body of __________ of sodium

13 to 17 g

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

20 to 25

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

50%

The amount of body heat (kcal) lost for each liter of sweat evaporated from the body's surfaces is _________________.

580

The hormone _________________ increases water reabsorption from the kidney tubules causing urine to become more concentrated.

ADH

_________________ is a substance that increases water reabsorption by the kidney tubules.

ADH

Which of the following statements is true regarding core temperature during exercise?

a well-regulated rise in core temperature occurs even during exercise in the cold

The hypothalamus _________________.

acts as a "thermostat" for temperature regulation

The hormone _________________ decreases sodium concentration in sweat, which aids in electrolyte conservation.

aldosterone

Which of the following factors is not associated with creating a distinct performance disadvantage for athletes who use diuretics to lose body water to rapidly "make weight"?

an increased hematocrit

The _________________ system serves as the "workhorse" to maintain thermal balance.

circulatory

_________________ provide "fine tuning" for temperature regulation.

circulatory adjustments

Heat loss by _________________ directly transfers heat through a liquid, solid, or gas from one molecule to another.

conduction

Transfer of heat via air movement is called _________________.

convection

The temperature of deep tissues in the body is known as _________________ temperature.

core

What type of cells play the most important role in initiating regulatory responses to cold environments?

cutaneous cold receptors

Body fluid loss coincides with which of the following?

decreased plasma volume

Which of the following is not a characteristic of the urine of well-hydrated individuals?

deep yellow-orange in color

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

dehydration

_________________ refers to an imbalance in fluid dynamics when fluid intake does not replenish water loss.

dehydration

Which of the following is not a benefit associated with hyperhydration to help protect the athlete to some extent against heat stress before exercising in a hot environment?

dilutes electrolytes in extracellular fluid

Pre-exercise hyperhydration _________________ the need to continually replace fluid during exercise.

does not replace

Sweat glands are classified as ___________ glands.

eccrine

Heat loss through _________________ provides the major physiologic defense against overheating.

evaporation

_________________ is the most serious and complex heat-stress malady and requires immediate medical attention.

exertional heat stroke

True or false? Aldosterone facilitates sodium absorption by the small intestine.

false

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

false

True or false? Heat exhaustion is the most serious and complex heat-stress malady and requires immediate medical attention.

false

True or false? Relative humidity has no impact on the effectiveness of evaporative heat loss.

false

True or false? Research demonstrates that extreme exercise in a hot environment increases the requirements for all fat-soluble and water-soluble vitamins.

false

True or false? Sweat is hypertonic compared with other body fluids.

false

True or false? The clothing worn by the typical recreational exerciser thwarts the dissipation of heat generated during exercise to a greater extent than the uniform of American football players.

false

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

false

True or false? The endocrine system represents the "workhorse" for temperature regulation.

false

True or false? The pituitary gland contains the central coordinating center for temperature regulation.

false

True or false? The risk of heat illness decreases when a person begins exercising in a dehydrated state.

false

True or false? Wet-bulb temperature is the air temperature in the shade recorded by a mercury thermometer.

false

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

false

The _________________ provide(s) an important avenue for heat loss during exercise-induced hyperthermia.

head

_________________ represent(s) the most common heat illness among physically active people.

heat exhaustion

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

hyponatremia

The osmolality of sweat is considered _________________ in relation to other body fluids.

hypotonic

All of the following are associated with progressive dehydration except _________________.

increased blood flow to active muscles

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

increases

The risk for dehydration _________________ during vigorous cold-weather exercise.

increases

Which of the following represents the best clothing choice while participating in physical activity in hot temperatures?

light-colored, moisture-wicking clothing

During exercise in hot weather, competition exists between mechanisms that _________________.

maintain a large muscle blood flow and mechanisms that regulate body temperature

Aging blunts the magnitude of the sweating response in which of the following ways?

modifies the sensitivity of thermoreceptors

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

one can tolerate relatively high environmental temperatures as long as humidity remains low

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

overheating, evaporation, cool

Body heat loss that occurs via electromagnetic heat waves is called _________________.

radiation

Heat loss occurs by the physical mechanisms of _________________.

radiation, conduction, convection, and evaporation

Elevation in core body temperature causes _________________.

reduced stomach and intestinal moditility

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

reduces

Heat stress indices like the wet-bulb globe temperature index make use of _________________ to evaluate the potential heat challenge of an environment.

relative humidity

The term _________________ 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.

relative humidity

Sweat evaporation from the skin depends on what three factors?

skin exposed to the environment, temperature and relative humidity, and convective air currents

_________________ most readily facilitates fluid replenishment when added to an oral rehydration beverage.

sodium

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

sweat gland

True or false? Adequate hydration provides the most effective defense against heat stress.

true

True or false? Any degree of dehydration can impair the capacity of circulatory and temperature-regulating mechanisms to adjust to exercise demands.

true

True or false? Characteristics of heat exhaustion include weak, rapid pulse; low blood pressure in the upright position; headache; nausea; dizziness; "goose bumps"; and general weakness.

true

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

true

True or false? Core temperature rises quickly when heat gain exceeds heat loss during vigorous exercise in a warm environment.

true

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

true

True or false? Exercise in hot, humid weather produces a sweat rate of more than 1 L per hour, with a sweat-sodium concentration ranging between 20 and 100 mEq/L.

true

True or false? 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.

true

True or false? Full heat acclimatization cannot take place without exposure to environmental heat stress.

true

True or false? Heat acclimatization refers to the physiologic adaptations that improve heat tolerance.

true

True or false? Heat cramps most likely occur from an imbalance in hydration level and electrolyte concentrations.

true

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

true

True or false? Sweating rate increases directly with increases in ambient temperature.

true

True or false? The body's thermoregulatory mechanisms primarily protect against overheating.

true

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

true

True or false? Voiding small volumes of dark yellow urine with a strong odor provides a qualitative indication of inadequate hydration.

true

True or false? Women show heat tolerance similar to that of men of equal aerobic fitness at the same exercise level.

true

Which of the following should be done to the reduce risk of overhydration and hyponatremia in prolonged exercise?

two to 3 hours before exercise, drink 400 to 600 mL of fluid

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

vomiting and diarrhea

Which statement is true concerning thermoregulation and gender?

women are at least as efficient as men in thermoregulation during exercise when considering level of fitness and acclimatization