EX Phys Exam 3 Flashcards
inability to dissipate excess heat
Heat Stress
ability of body to maintain constant internal temperature
Thermoregulation
Receptors in periphery & CNS detect
Temperature changes
acts like thermostat
Hypothalamus
Factors determining thermoregulatory stress
Ambient temperature
Relative humidity
Wind speed
Relative humidity
% of water vapor held in air
Plays a major role in heat loss
Affects our perception of thermal stress
When high (regardless of temperature, limits evaporation)
Humidity
Mechanisms of Heat Loss
Convection
Conduction
Radiation
Evaporation
Convection:
Air blows over surface of skin
Conduction
Physical contact between 3 surfaces
Radiation
Molecules in motion emit electromagnetic waves
-Infrared rays
Evaporation
Water on skin turns to vapor
- Heat loss due to fluid evaporation
As body temp rises sweat production_____
increases
Sweat reaches _________ and _________
skin and evaporates
Evaporation accounts for ______% of heat loss during exercise, but only ________% at rest.
80% during exercise
20% at rest
Insensible water loss removes _____% with sweat
10%
In heat stress, increase ______ and ______
Heart rate and cardiac output
Redirects circulatory flow to periphery:
dissipate heat
cool blood
Circulatory and Metabolic responses to heat stress:
body temp _________
oxygen uptake ______
Muscle lactate levels _______
Increases
increases
increases
With heat stress sweating ______
Increases
High volumes of sweet causes:
Blood volume to _________
____ of electrolytes
Release of _____ and ________
Decreases
Loss
Aldosterone and ADH
Larger the body mass the greater ________
heat production
Body fat insulates making heat loss _________
difficult
Greater the fitness, the greater _________
Cardiac output
Greater cardiac output improves ability to ______ heat.
dissipate
Muscle cramps occur when one is exposed to ______
heat
Heat cramps result from :
Dehydration
Electrolyte imbalances
Whole body sodium deficit
Nueromuscular fatigue
Heat cramps are triggered by intense _______
exercise
Caused by failure to dissipate heat after intense exercise
Exertional Heat Stroke
In exertional heat stroke core temp is elevates to > ____
104 F
As heat increases, performance endurance _________
decreases
Measures to ensure optimal performance (3)
Prior acclimation
proper hydration
proper conditioning
Anaerobic and strength performance in heat depends on duration of ________ and duration of ________ exposure.
event
heat
Longer events are ______ likely to affect performance
more
Anaerobic and strength performance in heat stress can be improved by: (3)
Cooling methods
hydration
limit time of exposure in heat
Physiological adaptation to an artificial environment
acclimation
Physiological adaptation to a natural environment
acclimatization
Time course of adaptations:
- Cardiovascular: _ to _ days
- Temperature regulation: _ to _ days
- Conservation of Na: _ to _ days
- All Adaptations: up to _ days
Cardiovascular: 1-5 days
Temperature reg: 5-8 days
Conservation of Na: 3-9 days
All adaptations: up to 14 days
Absence of exposure, adaptations lost in ___ to ___ weeks
2.5 to 5 weeks
Adaptation occurring in Acclimation and Acclimatization:
- _______ core temperature at onset of sweating
Lower
Adaptation occurring in Acclimation and Acclimatization:
- _______ heat loss via radiation and concoction
Increase
Adaptation occurring in Acclimation and Acclimatization:
- _______ blood plasma
Increase
Adaptation occurring in Acclimation and Acclimatization:
- ________ HR at specific workload.
Decrease
Adaptation occurring in Acclimation and Acclimatization:
- ________ body-core temperature.
Decrease
Adaptation occurring in Acclimation and Acclimatization:
- ________ O2 consumption at given workload.
Decrease
Adaptation occurring in Acclimation and Acclimatization:
- _______ exercise economy.
Improved
Sweating cools the body, but it _________ it.
Dehydrates
