Skin and temperature regulation Flashcards
What is meant by man being homeothermic?
likes to keep body temperature around the same point
Core body temp
37+/-0.5
What happens if body temperature is above 41?
denature proteins
What happens if body temperature is below 30?
lose consciousness
List 4 things body temperature varies with
menstrual cycle
circadian rhythm
external temperature
activity
What is the biggest source of heat loss?
radiation
What receptors detect temperature changes?
cold and warm thermoreceptors
Where are peripheral thermoreceptors found?
skin eg face and scrotum
Where are central thermoreceptors found?
spinal cord, abdominal organs and hypothalamus
4 ways in which heat generated increases
metabolism
muscle activity
shivering thermogenesis
non shivering thermogenesis
Who is non shivering thermogenesis important in and why?
infants - brown adipose tissue
2 ways in which heat loss is decreased
vasomotor - sympathetic arteriolar constriction
behaviour eg add clothes
Define hypothermia
A fall in deep body temperature to below 35 degrees
Who is at risk of hypothermia?
neonates
elderly
vagrants
outdoor
Treating hypothermia
dry/insulate
slow rewarming with blankets
internal re-warming with hot drinks
fast re-warming by immersion in water
Vascular frostbite
vasoconstriction, increase in viscosity and thrombosis leading to anoxia
Cellular frost bite
ice crystals form in ECF
increase ECF osmolarity
move water into space leading to cell dehydration and death
Why is there more strokes and heart attacks in winter?
increased vasoconstriction and increased blood viscosity
2 ways in which heat production is minimised
decrease physical activity
decrease food intake
3 ways heat loss increased from body
vasomotor control - arteriolar dilation
sweating
behaviour eg remove clothes and increase surface area
What temperature does heat exhaustion occur?
37.5-40 degrees
What happens in heat exhaustion?
vasodilation and drop in central blood volume
excess sweating disturbs water and salt balance
Symptoms of heat exhaustion
headache, confusion, nausea, profuse sweating, clammy skin, tachycardia, hypotension, weak pulse, fainting and collapse
Heatstroke body temperature
above 40
Symptoms of heat stroke
hot dry skin and circulatory collapse
Most at risk groups of heat stroke
neonate and elderly
physical work in hot climate
non-breathable protective clothing
Treatment of heat stroke
move to cool environment remove clothing fan sponge with slightly warm water give fluids - IV and oral
What causes fever?
endogenous pyrogens
What happens to produce fever in infection and explain why paracetomol works
cyclo-oxygenase in hypothalamus produces prostaglandins
paracetomol blocks this enzyme
Body temperature set around a higher temp
endogenous pyrogens shift the set point
