Thermoregulation Flashcards
By what modes is heat gained and lost?
Heat is gained by internal production, convection, conduction and radiation
Its lost by evaporation, convection, conduction and radiation
How does convection work?
Known as “Fluid” conduction aka wind chill or water chill
How does the body detect temperature?
It has cold and warmth receptors
How do cold/warmth receptors work?
Cold receptors decrease firing rate when heated and increase when cooled. (Dynamic response)
They peak at 30*
Warmth receptors increase firing rate wehn heated and decrease when cooled (dynamic response). They peak at ~40*
They’re firing rate overlaps at 37*
Where are temp receptors found?
- Peripheral Thermoreceptors in skin (mainly face/scrotum) detect environmental temp.
- Central Thermoreceptors in spinal cord, abdo organs and hypothalamus detect core temp.
Where are temperature signals integrated and managed?
The hypothalamus
How does our body increase heat production in response to cold stress?
Increases heat production:
- Voluntary muscle activity
- Involuntary muscle activity (Shivering)
- Increasing metabolic rate
- Non-shivering thermogenesis (Brown adipose in babies)
How do our bodies decrease heat loss in cold stress?
- Symp. Arteriolar Vasoconstriction
- Behavioural Response (clothes, warm places & reduce surface area)
Define hypothermia?
A core body temp <35*
How does frostbite occur?
2 mechanisms of action:
Vascular:
- Vasoconstriction & thombi due to increased blood viscosity lead to anoxia
Cellular:
- Ice crystals form in ECF, increases osmolarity and pulling water out of cells
- Cellular dehydration leads to death
How do cold periods inflict risk of death?
People often get MIs and strokes following cold periods.
Thrombi, viscous blood and vasoconstriction all stress the heart and risk MIs & Stroke
How does the body decrease heat production in response to heat stress?
Decrease physical activity and food intake
How does the body raise heat loss in response to heat stress?
- Peripheral vasodilation
- Sweating
- Behaviroural changes (sprawling to raise surface area, removing clothes, shade)
Define heat exhaustion?
When core Temp reaches 37.5-40*
A disturbed fluid/salt balance due to sweatin causes vasodilation and so a drop in central blood volume
You get headahce,s confusion, nausea, clammy skin, hypotension, tachycardia, fainting
Define heat stroke?
When temp gets over 40* the temp control mechanisms fail.
You stop sweating and go into circulatory collapse
