Week 5: Thermoregulatory systems Flashcards
What is our internal (core) body temperature?
36.5 - 37.5 oC
Regarding core temperature, what are humans?
Homeotherms
Endotherms
What are the features of homeotherms?
Constant and regulated internal temperature
What are the features of endotherms?
Generate heat internally
Maintain high basal heat production
What is hypothermia?
Low body temperature
What body temperature does hypothermia occur?
<35.0oC
What happens if you have hypothermia?
Impaired movement
Coordination
Speech
Cognition
What is hyperthermia?
High body temperature
What temperature does hyperthermia occur?
> 38.0 oC
What causes hyperthermia?
Exercise or fever
What temperature does damage to cells occur?
> 42.0 oC
What effects skin temperature?
Ambient temp
Distance from core
Skin blood flow
What is specific heat capacity?
The amount of energy required to raise the temperature of a given substance by 1oC
How much heat energy does 1 litre of O2 consumption produce?
20 Kj
What is the law of conversation of energy?
Energy can neither be created of destroyed: It can only be transformed from one state to another
What type of reaction is it when we liberate chemical energy from food?
Exothermic
What type of reaction is it when we resynthesise ATP?
Endothermic
What are the two types of heat production?
Voluntary
Involuntary
Provide an example of voluntary heat production
Exercise
Provide an example of involuntary heat production
Shivering
Action of hormones
What hormones are released to produce heat?
Thyroxine
Catecholamines
How is heat gained externally?
Sky thermal radiation
Solar radiation
Ground radiation
How is heat lost?
Conduction
Convection
Radiation
Sweat evaporation
What is thermal gradient?
Heat transfer is always from higher to lower temperatures
What is conduction?
Heat transfer from the body to an object with direct contact (about 3% at rest)
What is convection?
Heat transfer to or from air or water (about 12% at rest)
What is radiation?
Transfer of heat in the form of electromagnetic waves
What is evaporation?
Vaporisation of sweat from water to vapour
How much heat do we lose per one gram of sweat?
2.41KJ
Where is sweat released from?
The sweat glands
What is sweat stimulated by?
Sympathetic nervous system
What three things influence evaporation?
Temperature
Convective currents
Skin exposure
How does hyperhermia effect sprint/power performance?
Improves it
How does hyperhermia improve sprint/power performance?
Decreases resistance of muscles/joints Faster nerve conduction velocity Improvement in muscle contractile elements Faster metabolic rate Increased SNS activity
How does hyperthermia effect endurance performance?
Impairs it
How does hyperthermia effect repeated sprint performance?
Impairs it
What are the cognitive consequences of hyperthermia?
Fatigue perception increase Scanning vigilance Reaction time Attention Visual motor tracking
What are the effects of heat acclimation?
Body temp will be lower at a given heat
Sweat rate increases and sweat becomes more dilute
Skin blood flow is reduced, more blood to muscles
Blood volume increases or does not decrease
SV maintained
