Skin and temperature control Flashcards Preview

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Flashcards in Skin and temperature control Deck (17)
1

What is normal core body temp?

normally 37 ± 0.5°C

2

Describe the differences between central and peripheral thermoreceptors

Peripheral thermoreceptors
• Located in the skin, especially in face, scrotum
Central thermoreceptors
• Located in spinal cord, abdominal organs, hypothalamus

3

How does the body generate heat when you're cold?

General metabolism
• Oxidative phosphorylation and other chemical reactions are not 100% efficient

Voluntary muscular activity
• “Futile” muscular activity e.g. rubbing hands etc

Shivering thermogenesis
• Involuntary muscular activity to produce heat

Non-shivering thermogenesis
• In humans, only significant in infants, due to brown adipose tissue

4

How does the body reduce heat loss when you're cold?

Vasomotor control
• Sympathetic arteriolar constriction reduces delivery of blood to the skin

Behavioural responses
• Reducing surface area, adding clothing, moving to warmer environment

5

Define hypothermia

A fall in deep body temperature to below 35ºC

6

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

Outdoor pursuits

North Sea workers

7

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

8

What is involved in the pathology of frostbite?

Vascular component
• Vasoconstriction
• Increase in viscosity of blood as it chills
• Promotes thrombosis
• Causes anoxia

Cellular component
• Ice crystals form in extracellular space
• Increases extracellular osmolality
• Causes movement of water from intracellular space
• Cell dehydration and death

9

How does the body reduce head production when they become too hot?

o Decreased physical activity
o Decreased food intake

10

How does the body increase heat loss when they're warm?

Vasomotor control
• Arteriolar dilation increases delivery of blood to the skin

Sweating
• Sympathetic cholinergic fibres increase evaporative heat loss

Behavioural responses

Increasing surface area, removing clothing, moving to shaded area

11

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

12

Describe heat stroke

– Body temperature raised above 40ºC

– Body’s temperature control mechanisms fail

– Symptoms include hot dry skin (sweating ceased) and circulatory collapse

13

When does heat exhaustion become heat stroke?

When body temperature raises above 40ºC

14

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

15

How do you treat heat stress?

– Move to cool environment
– Remove clothing
– Fan
– Sponge with tepid water
– Give fluids (oral, intravenous)

16

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

17

What drugs reduce fever?

aspirin & paracetamol - inhibit COX