Flashcards in Skin and temperature control Deck (17)
What is normal core body temp?
normally 37 ± 0.5°C
Describe the differences between central and peripheral thermoreceptors
• Located in the skin, especially in face, scrotum
• Located in spinal cord, abdominal organs, hypothalamus
How does the body generate heat when you're cold?
• Oxidative phosphorylation and other chemical reactions are not 100% efficient
Voluntary muscular activity
• “Futile” muscular activity e.g. rubbing hands etc
• Involuntary muscular activity to produce heat
• In humans, only significant in infants, due to brown adipose tissue
How does the body reduce heat loss when you're cold?
• Sympathetic arteriolar constriction reduces delivery of blood to the skin
• Reducing surface area, adding clothing, moving to warmer environment
A fall in deep body temperature to below 35ºC
Who are those at risk of hypothermia?
Neonates - big SA:volume, not much fat, don’t shiver well, but do have BAT
Elderly - do not detect temp change so well, less shivering capacity, more immobile
Vagrants – homeless individuals
Cold store workers
North Sea workers
How do you treat hypothermia?
– Dry/insulate to prevent further heat loss
– Slow re-warming with bag/blankets
– Internal re-warming with hot drinks and/or warm air
– Fast re-warming by immersion in water
What is involved in the pathology of frostbite?
• Increase in viscosity of blood as it chills
• Promotes thrombosis
• Causes anoxia
• Ice crystals form in extracellular space
• Increases extracellular osmolality
• Causes movement of water from intracellular space
• Cell dehydration and death
How does the body reduce head production when they become too hot?
o Decreased physical activity
o Decreased food intake
How does the body increase heat loss when they're warm?
• Arteriolar dilation increases delivery of blood to the skin
• Sympathetic cholinergic fibres increase evaporative heat loss
Increasing surface area, removing clothing, moving to shaded area
Describe heat exhaustion
– Body temperature raised in range 37.5-40ºC
– Results in vasodilation and drop in central blood volume
– Caused by a disturbance of the body’s fluid/salt balance due to excessive sweating
– Symptoms include headache, confusion, nausea, profuse sweating, clammy skin, tachycardia, hypotension, weak pulse, fainting & collapse
Describe heat stroke
– Body temperature raised above 40ºC
– Body’s temperature control mechanisms fail
– Symptoms include hot dry skin (sweating ceased) and circulatory collapse
When does heat exhaustion become heat stroke?
When body temperature raises above 40ºC
Who are those at most risk of heat stress?
– Neonates and the elderly
– People doing physical work in hot humid environments
– Workers wearing non-breathable protective clothing e.g. fireman
How do you treat heat stress?
– Move to cool environment
– Remove clothing
– Sponge with tepid water
– Give fluids (oral, intravenous)
What causes fever?
• Part of the body’s mechanism for fighting infection
• Caused by endogenous pyrogens (IL-1, IL-6)
• Concept of ‘set point’ controlled by the hypothalamus
– Endogenous pyrogens shift the set point to turn it up
– Caused by local production of prostaglandins by cyclo-oxygenase (COX) in the hypothalamus