Flashcards in Temperature Control Deck (12):
How does the body generate heat (intentionally and unintentionally)?
Voluntary - muscle movement
Involuntary - shivering
Nonshivering - brown fat etc.
How is heat loss minimised by the body?
Vasomotor control - arteriolar constriction reduces blood to skin
Behavioural - reducing surface area, adding clothing, moving to warmer environment
What body temperature is considered hypothermia?
What groups are particularly at risk of hypothermia?
Neonates - shiver poorly, large surface area:volume
Elderly - don't detect body changes as well
Cold store workers
North sea workers
How is hypothermia treated?
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, extracorporeal circulation
What are the different types of frostbite and how does each form?
Vascular vs Cellular
- increase in viscosity
- promotes thrombosis and causes anoxia
- ice crystals form in extracellular space
- increases extracellular osmolality
- causes movement of water from cell
- cell dehydration and death
How does the body deal with increased body temperature?
Heat production minimised
- decreased physical activity and food intake
Vasomotor control - increased blood to skin
Sweating - sympathetic cholinergic fibres
Behavioural responses - increased surface area, removing clothing, shade
What are the different levels of hyperthermia? What temperatures cause each?
Heat exhaustion (heat illness) - 37.5-40degress
Heat stroke (heat injury) - >40degrees
What are the physiological responses in heat exhaustion, and the symptoms/signs?
Vasodilation and drop in central blood volume
Caused by a disturbance of the body's fluid/salt due to excessive sweating
Profuse sweating, clammy skin
Tachycardia, hypotension, weak pulse
What are happens in heat injury and what are the symptoms/signs?
Body's control mechanisms fail
Hot dry skin (sweating ceased)
What groups are at increased risk of hyperthermia?
Those doing physical work in hot environments
Workers wearing non-breathing PPE