skin and temperature control Flashcards
What is the normal body temperature
37 plus or minus 0.5 degrees
What do warm temperature receptors do in response to warm temperature
Warm receptors Increase in frequency
Cold receptors decrease in frequency
What do cold receptors do in response to temperature drop
Cold receptors Increase in frequency
Warm receptors - decrease in frequency
Where are peripheral thermoreceptors located
Skin - especially face and scrotum
Where are central thermoreceptors located
hypothalamus, spinal cord and abdominal organs
What do peripheral thermoreceptors respond to
Change in environmental temperature
What do central thermoreceptors respond to
Change in core body temperature
What generates heat in the body
Increased metabolism
futile muscular activity - muscles produce heat when doing activity
Shivering thermogenesis - involuntary muscle movement
non-shivering thermogenesis - mainly occurs in infants
Why does non-shivering thermogenesis mainly occur in infants
Because it occurs in brown fat
What reduces heat loss from the body
Sympathetic arterial constriction which limits the blood being delivered to the periphery
Behavioural responses - adding clothes, reducing surface area and moving to warmer areas
What is hypothermia
Core body temperature dropping below 35 degrees
Who is most at risk of hypothermia
Neonates - not much fat but have brown fat so they can do non shivering thermogenesis - They also have large surface area so they lose more heat
Elderly
Homeless people
What is the treatment for cold stress
Insulation to prevent further heat loss
Slow re-warming blankets
Internal reheating with warm drinks or hot air
Immersing the body in warm water
Extracorpeal circulation - taking blood out of the body, warming it up, and then putting it back into the body
What are the consequences of cold stress
Frost bite
Vasoconstriction to prevent heat loss which promotes thrombosis and causes anoxia
Ice crystals can form in extracellular space which causes water to try equiblirate and follow the crystal which dehydrates cells
What is frostbite
vasoconstriction and increased viscosity as a response to cold temperatures which causes anoxia and leads to cell death
how does cold temperature increase risk of myocardial infarction
Cold temperatures cause vasoconstriction and increase viscosity which increases the afterload on the heart so the heart has to work harder to pump blood around the body and this increases risk of MI
What reduces heat production
Decreased physical activity and food intake
What increases heat loss from the body
Vasodilation which increases blood delivery to the skin
Sweating - increases heat loss via evaporation
Behavioural responses - taking off clothes
What causes sweating
Sympathetic cholinergic fibres
What is heat exhaustion
Body temp 37.5-40 degrees
Results in vasodilation and drop in central blood volume due to excess sweating which also cayuses issues with the fluid salt balance
What are the symptoms of heat exhaustion
Headache
confusion
nausea
profuse sweating
clammy skin
tachycardia
hypotension
weak pulse
fainting
What is heat stroke and its main symptom
Body temp above 40
Failure of body temperature control
Symptoms - hot dry skin due to no sweating and circulatory response
Who are the most at risk for heat and cold stress
neonates and elderly
What is the treatment for heat stress
Move to cool environment
remove clothing
fan
sponge with tepid water - not too cold or hot
Give fluids - oral or IV
What causes fever and why do fevers occur
Pyrogens
Fevers occur to fight off infections
how do pyrogens produce a fever
Cause production of prostaglandins by cyclo-oxygenase in the hypothalamus
Why are aspirin and paracetamol antipyretics
They inhibit cyclo-oxygenase so the set temperature cannot be increased
