Temperature Control

Question 1

How does the body generate heat (intentionally and unintentionally)?

Answer 1

General metabolism
Voluntary - muscle movement
Involuntary - shivering
Nonshivering - brown fat etc.

Question 2

How is heat loss minimised by the body?

Answer 2

Vasomotor control - arteriolar constriction reduces blood to skin
Behavioural - reducing surface area, adding clothing, moving to warmer environment

Question 3

What body temperature is considered hypothermia?

Answer 3

<35degrees

Question 4

What groups are particularly at risk of hypothermia?

Answer 4

Neonates - shiver poorly, large surface area:volume
Elderly - don’t detect body changes as well
Vagrants
Cold store workers
Outdoor pursuits
North sea workers

Question 5

How is hypothermia treated?

Answer 5

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

Question 6

What are the different types of frostbite and how does each form?

Answer 6

Vascular vs Cellular

Vascular

• vasoconstriction
• increase in viscosity
• promotes thrombosis and causes anoxia

Cellular

• ice crystals form in extracellular space
• increases extracellular osmolality
• causes movement of water from cell
• cell dehydration and death

Question 7

How does the body deal with increased body temperature?

Answer 7

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

Question 8

What are the different levels of hyperthermia? What temperatures cause each?

Answer 8

Heat exhaustion (heat illness) - 37.5-40degress
Heat stroke (heat injury) - >40degrees

Question 9

What are the physiological responses in heat exhaustion, and the symptoms/signs?

Answer 9

Vasodilation and drop in central blood volume
Caused by a disturbance of the body’s fluid/salt due to excessive sweating

Headache, confusion
Nausea
Profuse sweating, clammy skin
Tachycardia, hypotension, weak pulse
Fainting/collapse

Question 10

What are happens in heat injury and what are the symptoms/signs?

Answer 10

Body’s control mechanisms fail
Hot dry skin (sweating ceased)
Circulatory collapse

Question 11

What groups are at increased risk of hyperthermia?

Answer 11

Neonates
Elderly
Those doing physical work in hot environments
Workers wearing non-breathing PPE

Question 12

What are the treatments for hyperthermia?

Answer 12

Move to cool environment
Remove clothing
Fan
Sponge with tepid water
Give fluid - oral or IV