Transfer of heat from a solid object to a solid object is
a. convection
b. evaporation
c. conduction
d. radiation
c. conduction
Transfer of heat from air or water currents is
a. convection
b. evaporation
c. conduction
d. radiation
a. convection
The primary avenue of heat loss during exercise is
a. convection
b. evaporation
c. conduction
d. radiation
b. evaporation
Which of the following can serve as modes of both heat gain and heat loss from the body?
a. radiation
b. convection
c. conduction
d. All of these are correct.
d. All of these are correct
Which of the following takes place as a result of the cardiovascular system's adjustment to exercise in a hot environment?
a. increased heart rate
b. decreased blood pressure
c. shunting of blood to the skin
d. All of these are correct
d. All of these are correct
Exercise training and repeated heat exposure will decrease the concentration of _______________ in one's sweat.
a. potassium
b. calcium
c. sodium
d. all of these
e. none of these
c. sodium
The heat disorder brought on by sodium losses and dehydration that accompanies high rates of sweating is
a. heat cramps
b. heat exhaustion
c. heatstroke
d. heat prostration
a. heat cramps
An increase in internal body temperature to a value exceeding 40�C (104� F), cessation of active sweating (although sweat may remain on the body), rapid bounding pulse and respiration, and confusion, disorientation, or unconsciousness are all signs and sy
c. heat stroke
Extreme fatigue, dizziness, nausea, vomiting, fainting, and a weak, rapid pulse are all signs and symptoms of
a. heat cramps
b. heat exhaustion
c. heatstroke
d. heat prostration
b. heat exhaustion
During exercise in the cold, muscle
a. shortening velocity increases
b. contractile force decreases
c. fiber recruitment generates more power
d. contraction is inhibited only in deep muscles
b. contractile force decreases
Heat Gain
Metabolic Heat & Environmental Heat (conduction, convection, radiation)
Heat Loss
Radiation, Conduction, Convection, Evaporation
Convection
Transfer of heat from one place to another by the movement of fluids (liquid/gas).
Conduction
Diffusion of heat to body by direct contact.
Acclimation
Short-term adaptation to environmental stressor over time (days to weeks)
Acclimatization
Long-term adaptation to environmental stressor over time (months to years)
What is the percentage of ATP production is used for physiological functions versus producing metabolic heat?
25% versus 75%
Which two methods are the body's primary way to eliminate heat?
Radiation and convection.
Radiation
Heat loss in the form of infrared rays
How does humidity affect heat loss?
High humidity limits sweat evaporation and heat loss while low humidity encourages it.
What is the body's "thermostat" and what relays temperature changes to it?
Preoptic-Anterior Hypothalamus and Thermoreceptors.
When the POAH senses deviation from core body temp, where does it send its signals to?
Sympathetic Nervous System (SNS)
What are the four sets of effectors that SNS sends signals to?
Skin arterioles, Eccrine sweat glands, Skeletal muscle, & Endocrine glands.
Skin arterioles
Vasoconstriction: minimizes heat loss
Vasodilation: enhances heat loss
Which neurotransmitter activates the eccrine sweat glands?
Acetylcholine
Skeletal muscle
Produce more heat (shivering)
Endocrine gland
Hormonal production to increase heat production via metabolic rate and release thyroxine to cool.
What are the two limitations of exercise in the heat?
Cardiovascular system overload: insufficient blood flow to muscle and skin, especially newbies.
Critical Temperature Theory: when critical temp is reached (41 C), brain shuts down exercise, explanation for well-trained.
When are vasopressin or arginine vasopressin hormones released?
Loss of both electrolytes and water in sweat.
What does aldosterone or antidiuretic hormone (ADH) do?
Aldosterone: retains sodium in kidney
ADH: retains water in kidney
How does sweating affect blood volume and cardiac output?
Decreases them which limits performance potential.
Which electrolytes can be reabsorbed when sweating?
Sodium and chloride.
List the order of heat disorder from mild to severe.
Heat cramps
Heat exhaustion
Heat stroke
How to measure heat stress in environment?
Wet-bulb globe temperature
Heat cramps
Sodium losses and dehydration by high rates of sweating
Heat exhaustion
Cardiovascular system's inability to meet body's needs as dehydration occurs. Insufficient blood volume and sodium depletion.
Heat stroke
Possible coma & brain damage
How does body minimize excessive heat loss during cold exposure?
1) Peripheral vasoconstriction
2) Non-shivering thermogenesis: increased metabolic rate=increased heat production
3) Shivering: involuntary contraction and relaxation of skeletal muscles increase heat
What are the 6 risk factors of exercise in heat?
Metabolic heat production
Air temperature
Humidity
Air velocity
Radiant heat sources
Clothing
Hyperthermia
Excessive heat (high core body temp)
Hypothermia
Excessive cold (low core body temp)
Three patterns of cold adaptation.
1) Cold habituation
2) Metabolic acclimation
3) Insulative acclimation
Cold habituation
Occurs after repeated cold exposures without significant heat loss. Vasoconstrictor & shivering blunted, core temp falls greater. Small areas of skin often exposed: hands/face.
Metabolic acclimation
Occurs after repeated cold exposures with heat loss. Enhanced metabolic, shivering heat production
Insulative acclimation
When metabolism cannot prevent heat loss. Enhanced skin VC (peripheral tissue insulation)