FINAL EXAM THERMOREGULATION YOU ARE HOT!! :p Flashcards
(25 cards)
What is the normal range for core body temperature in humans?
97°F–100°F
When is core body temperature typically lowest and highest?
Lowest during sleep; highest during exercise or in hot environments
What are common methods used to assess body temperature?
Oral, axillary, temporal, rectal, and ingestible thermometers
What part of the brain acts as the body’s internal thermostat?
The preoptic/anterior hypothalamus (POAH)
ow does the POAH respond when it perceives heat?
: It increases heat loss by dilating peripheral blood vessels.
How does the POAH respond when it perceives cold?
It decreases heat loss by constricting peripheral blood vessels, redirecting blood to the core.
What are the main factors that increase heat gain in the body?
Resting Metabolic Rate (RMR)
Muscle activity
Hormonal and nervous system activity
Thermic effect of food
Non-exercise activity thermogenesis (NEAT)
Warm environments
What is NEAT and how does it affect heat gain?
: NEAT (Non-exercise activity thermogenesis) is the heat produced by daily movements like fidgeting or walking, contributing to overall heat gain.
What are the five main ways the body loses heat?
Conduction – Transfer of heat through direct contact (e.g., sitting on a cold bench)
Convection – Transfer of heat through moving air or water (e.g., wind or a fan)
Radiation – Loss of heat in the form of infrared rays, even without contact
Evaporation – Heat loss via sweat turning into vapor (main way during exercise)
Excretion – Minor heat loss through urine and feces
What factors influence thermoregulation in the body?
Gender – Females may dissipate heat differently due to body composition and hormones
Age – Older adults and young children have less efficient thermoregulation
Body size & composition – More body fat insulates, while more muscle generates more heat
Conditioning level – Fitter individuals sweat sooner and regulate temperature better
Hydration status – Dehydration impairs the body’s ability to cool itself
Clothing – Impacts heat retention or dissipation
Environmental factors – Temperature, humidity, and wind all affect heat gain/loss
How does the body thermoregulate in hot environments?
Peripheral receptors detect increased skin temperature
Signals are sent to the POAH (preoptic/anterior hypothalamus) and cerebral cortex
POAH stimulates the SNS to:
Vasodilate surface arterioles → brings more blood to the skin for heat loss
Activate sweat glands (eccrine glands) → sweat evaporates to cool the body
What are the two competing cardiovascular demands during heat stress?
Delivering oxygen and nutrients to exercising muscles
Increasing blood flow to the skin for heat removal
How does the body meet the increased demand for cardiac output during heat stress?
Increases heart rate and contractility
SNS causes:
Vasoconstriction in nonessential organs
Vasodilation in muscles and near the skin surface
: What happens when core body temperature reaches 104°F during exercise?
he brain typically signals the body to stop exercising to prevent overheating.
How does rising core temperature affect hormone levels during exercise?
It increases epinephrine levels, which enhances glycogen utilization.
What is Exertional Heat Stroke?
A condition from intense or prolonged exercise causing collapse or withdrawal, often with organ system failure.
What core temperature defines exertional heat stroke?
a rectal or GI temperature >104°F to 105°F (or >40°C).
What is the recommended treatment for exertional heat stroke?
Cold water immersion.
How long does it take to acclimate to heat stress?
9–14 days.
How should training be modified to optimize heat acclimation?
Reduce volume and intensity initially, and train below 70% VO₂max for 20–60 minutes per session.
What are the adaptations to heat stress?
Increased blood volume
More effective cardiac output and blood distribution to the skin
Improved cutaneous blood flow within peripheral regions
Increased sweat rates
Decreased sweat thresholds
More effective distribution of sweat
Decreased electrolyte concentrations in sweat due to improved reabsorption efficiency.
What does Oral Rehydration Therapy contain?
Salt
Glucose
Potassium chloride
Trisodium citrate
Mixed with 1 liter of water.
How does the body respond to cold environments?
A:
Peripheral receptors sense cold environmental temperatures.
The cerebral cortex controls voluntary actions by creating movement.
The POAH activates SNS response via norepinephrine to vasoconstrict surface arterioles and redirect blood to the core.
Non-shivering thermogenesis and shivering help generate heat.
Voluntary muscle action contributes to heat production.
What are the risks associated with cold stress?
Core temperature drops between 90°F and 95°F.
This can lead to hypothermia, which affects physiological functions and can be life-threatening.
