20. Thermoregulation Flashcards
What is normal body temperature?
37-39 degrees
What are the two main differentiations of temperature
Core temperature (37-39) Skin temperature (much larger range)
What are the normal ranges of core temperature that human can survive?
27-45 degrees
What equation defines body temperatue
Metabolic heat production +/- radiant heat exchage +/- Convection - evaporative heat loss
What methods does the body have to increase temperature
Metabolic thermogenesis (brown fat)
Changes in heat exchnage (skin and cardiovascular systems)
Shivering
Increased metabolic rates (hormones)
Explain the physiology of metabolic thermogenesis
Brown fat tissue contains an UCP protein
This allows the electrons from the electron transport chain to “short circuit” and recyle very quickly
This produces a lot of heat
What happens to the body when it is warm?
Blood redistrubuted to periphery
Stroke volume, central venous pressure and blood flow is reduced
What area is the co-ordination centre for temperature regulation?
Hypothalamus
What is the main mechanism of heat loss?
Evaporative
1 litre of sweat removes 2.4MJ of heat
6-8 litres lost in a marathon
What happens to blood flow to the skin during exercise
Total amount of perfusion increases
Percentage amount reduces
What is the hierachy control of blood pressure to maintaining temperature?
- Always maintain blood pressure
- Maintain Muscle blood flow
- Maintain skin blood flow
What happens to ATP in heat stress
Why
It increases
Heat triggers ATP secretion into the vascular lumen acting as a vasodilator
This allows more blood flow to take heat away more easier
What neurotransmitters activate sweat glands
Acetylcholine
Noradrenaline
isopreoterenol
What are the negative effects of dehydration?
Reduced performance
Confusion
Collpase
Renal failrure/hypovolaemia
Death
How does dehydration effect cardiac function?
Reduced cardiac output
Because of
Reduced Stroke volume
What can be saids to the effects of training on temperature regulation?
The more trained you are the better you are to control effects of temperature changes.
What is the effect of dehydration on muscle strength?
Unknown
All the studies are poor. Induced dehydration is very different ways
What are the health problems associated with dehydration
Rhabdomylosis
Dehydration
Heat exhaustion/heat stroke
What happens to oxygen consumption during hypothermia?
Increased metabolic rate
What is cold stress diuresis
Maximum vasocontriction causes increased sensed blood volume
This leads to ADH being inhibited
What happens to jump height in hypothermia?
Reduced, hypothesis to be due to reduced neuromuscular activation
