Skin temperature and control Flashcards
What does homeothermic mean?
We regulate our own body’s temparature
hOW MUCH CAN BODY TEMPERTURE DROP IN DEEP SLEPE?
1 ‘C
How much head production to we make at rest? Onn a brisk walk?
80kcal/hour
600kcal/hour
How do we lose heat?
Convection
Conduction
Evaporation (resp +sweating, 600ml/day at rest, 4L/hr at extremes)
Radiation (60% heat loss)
Cold receptor peak firing rte
25’C
Warm receptor peak firing ratw
40’C
Where are erhiperhal thermo receptors?
Skin (esp face and scrotum)
WHere ar ecentral thermo receptors?
Spinal chord, abdo. organs, hypothalmus
What does the Hypothalmus do?
Takes in all the information and decides what to do with it! (from perioheral and central chemoreceptors)
How do we respond to cold stress
General metabolism (from not 100% efficient processes)
Voluntary muscular activity (“Futile” activity)
Shivering thermogenesis
Non-shivering thermogenesis (brown adipose tissue in infants)
Arteriorlar constriction
Add clothing, move to a warmer area, reduce surface area
What degree cut off arfor hypothermia?
35’C
What are the cellular and vsacular complications of cold stress?
Vascular:
-Vasoconstriction +increased viscosity of blood, promotes thrombosis
-anoxia
-death
Cellular:
-ice forms in extracellular space,
-osmotic gradient
-cell dehydration and death
Excess winter mortalilty in the UK. Why?
40%
Colds, flu
Also increased MI and strokes due to colder temps and increasde viscosity of blood and increased vasoconstriction etc
What temps for heat exhaustion?Heat stroke signs
37.5-40’C:
vasodilation -> drop in central blood volume
fluid/salt inbalance due to excess sweating
-headache, confusion, nausea, sweating, clammy skin, tachycardia, hypotension, weak pulse, fainting, collapse
Heat stroke = over 40’C
Body’s control mechanisms fail, hot DRY skin, circilatory collapse
Whiat causes fever?
endogenous pyrogens - IL1 IL6 to hyperthalmus and increases “set point “ above 37’C.
