Chapter 12: Temperature Regulation

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

Identify a primary adaptation of heat acclimation

Increased plasma volume

Identify a true statement about the process of conduction

It requires physical contact between the body and an object

Identify the response of the hypothalamus to an increase in core temperature

It stimulates the sweat glands

Identify the most important means of heat loss during exercise

evaporation

Heat production increases during exercise due to muscular contraction and is directly proportional to the _____

exercise intensity

The input to the temperature-regulating centers in the preoptic-anterior hypothalamus (POAH) comes from receptors in the _____ and the core

skin

The progressive decline in muscle blood flow during exercise in a hot or humid environment is due to competition for blood between the working muscles and the _____

skin

The term ____ _____ refers to the amount of heat energy required to raise 1 kg of body tissue by 1 C

specific heat

Heat/cold-sensitive neurons that sense changes in the core temperature of the body are located in both the _____

spinal cord and the preoptic-anterior hypothalamus

Complete loss of heat tolerance can occur following _____ of no heat exposure

28 days

Identify the results of the body's inability to lose heat during exercise in a hot/humid environment. (Check all that apply.)

-A high sweat rate (more fluid loss) -A high core temperature

Which of the following help cold-acclimatized people maintain heat production with less shivering? (Check all that apply.)

-An increase in the release of norepinephrine -An increase in nonshivering thermogenesis

During exercise in a hot environment, what are the major changes that occur in muscle metabolism that contribute to muscle fatigue? (Check all that apply.)

-Increased muscle lactate production -Increased skeletal muscle production of free radicals

Identify the end result of heat acclimation during submaximal exercise. (Check all that apply.)

-Lower heart rate -Lower core temperature

During exercise, specific heat for the human body is _____ per kilogram of body mass

0.83 kilocalorie

Heat tolerance can decline significantly within _____ of no heat exposure

7 days

Heat acclimation in athletes is achieved within _____ after the first exposure

7 to 14 days

Identify an impact of hyperthermia on the central nervous system

A reduction in the mental drive for motor unit recruitment

_____ is very effective in transporting heat because it has a high capacity to store heat

Blood

_____ is a form of conductive heat loss in which heat is transmitted to either air or water molecules in contact with the body.

Convection

Identify a true statement about exercising in a cold environment

It enhances an athlete's ability to lose heat

Which of the following is true of the response of the preoptic-anterior hypothalamus (POAH) to cold?

It initiates the release of norepinephrine

Which of the following is true of piloerection reflex?

It is a response to a significant drop in core temperature

Identify a common site of core temperature measurement in a laboratory setting

Rectum

True or false: People and many animals live their entire lives only a few degrees from their thermal death point

True

_____ temperature can be used as a good estimate of the actual brain temperature

Tympanic

Match the types of heat production in the body (in the left column) with their mechanisms (in the right column).

Voluntary heat production --> Heat produced during exercise Involuntary heat production --> Heat produced by shivering

Heat acclimation results in an earlier onset of sweat rate, which translates into _____

a lower core temperature

Evaporation occurs due to _____

a vapor pressure gradient between the skin and the air

The physiological adaptation that occurs when an individual undergoes repeated exposure to a stressful environment is referred to as

acclimation or acclimatization

The method of heat loss during continuous exercise is modified according to the _____

ambient conditions

The Heat Index is a measure of the _____

body's perception of how hot it feels

In the context of the four processes by which heat loss from the body may occur, radiation refers to heat loss _____

by infrared rays

Heat stress during exercise in a hot or humid environment can result in _____

cardiovascular strain

The transfer of heat from the body into the molecules of cooler objects in contact with its surface is referred to as _____

conduction

A key aspect of heat acclimation is a(n) _____

earlier onset of sweating

Once the hypothalamus responds to an increase in body temperature due to exercise, the internal temperature reaches a new _____

elevated steady-state level

True or false: High humidity decreases an individual's perception of how hot the environment feels

false

True or false: The temperature-maintenance strategy of homeotherms uses a "refrigerator" rather than a "furnace" to maintain body temperature at a constant level

false

True or false: People who are cold acclimated begin shivering at a higher skin temperature when compared to unacclimated individuals

false People who are cold acclimated begin shivering at a LOWER skin temperature when compared to unacclimated individuals.

When the body is attempting to lose heat, blood _____

flow is increased to the skin

The maintenance of a constant body temperature requires _____

heat loss to match the rate of heat production

When the relative humidity is high, the Heat Index of the body is also high due to an increase in _____

heat storage

Humans and other animals that maintain a rather constant body core temperature are called _____

homeotherms

The combined effect of fluid loss and high core temperature increases the risk of _____

hyperthermia

The combination of metabolic heat production and warm clothing prevents the development of _____ during short-term work on a cold day

hypothermia

Both hyperthermia and dehydration can directly diminish exercise performance by _____

impairing the function of the central nervous system

When human body temperature rises above 450C, it results in a(n) _____

inability to produce cellular energy

During prolonged exercise in the heat, there is a(n) _____ in the body

increase in the rate of muscle glycogen degradation

When the body temperature rises, the temperature control center in the brain responds by _____

increasing the rate of heat loss

Biochemical heat production caused by the secretion of hormones such as thyroxine and catecholamines is considered _____

involuntary heat production

In the body, the amount of heat loss due to convection is dependent on the _____

magnitude of the airflow over the skin

Women generally tolerate mild cold exposure better than men because they have _____

more body fat

According to the temperature-maintenance strategy of homeotherms, the body temperature is set _____

near the high end of the survival range

According to many exercise physiologists, _____ is the only serious threat to health from exercise

overheating

The temperature control center is an area in the brain called the _____, which works like a thermostat

preoptic-anterior hypothalamus

_____ involves the transfer of heat from the surface of one object to the surface of another, without any physical contact

radiation

In the context of continuous exercise, as the ambient temperature increases, there is a decrease in the _____

rate of convective and radiative heat loss

Additional insulation from more subcutaneous fat improves cold tolerance by _____

reducing the rate of heat loss

Identify the most important factor influencing the rate of evaporative heat loss at high environmental temperatures

relative humidity

The Heat Index is calculated by combining the air temperature and _____ to compute an apparent temperature

relative humidity

Long-term exercise in a hot or humid environment is a serious challenge to _____

temperature homeostasis

Cooling by way of evaporation is most effective _____

under conditions of low humidity

In response to an increase in core temperature, the vasomotor control center _____

withdraws the normal vasoconstrictor tone to the skin


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