Skin and Temperature

Question 1

What does body temp vary with?

Answer 1

• External temp
• Activity
• Circadian rhythm
• Menstrual cycle

Question 2

Why is there a need for a narrow range of deep body temperature?

Answer 2

• Above 41°C → proteins start to denature

- Below 30°C → lose consciousness

Question 3

What is core body temp maintained at?

Answer 3

37 ± 0.5°C

Question 4

What are the 4 methods of Thermal balance in humans?

Answer 4

• Convection (loss and gain)
• Conduction (loss and gain)
• Evaporation (loss)
• Radiation (loss and gain)

Question 5

Where is the location of the central thermoreceptors?

What do they respond to?

Answer 5

• Spinal cord, Abdominal organs, Hypothalamus

- They respond to changes in core body temp

Question 6

Where is the location of the peripheral thermoreceptors?

What do they respond to?

Answer 6

• Skin!
• > (esp. face and scrotum)
• They respond to changes in environmental temperature

Question 7

How is heat generated by the body in response to cold stress?

Answer 7

• General metabolism
• Voluntary muscular activity
• Shivering thermogenesis
• Non-shivering thermogenesis
• > (only significant in infants due to brown adipose tissue)
• Vasomotor control
• > sympathetic arteriolar constriction reduces delivery of blood to the skin
• Behavioural responses
• > reduced surface area, adding clothing, moving to a warmer environment

Question 8

Why is mortality increased in winter?

Answer 8

• due to the increase in heart attacks and strokes following periods of cold weather
• increased vasoconstriction and increased blood viscosity contribute

Question 9

How is heat production minimised by the body in response to heat stress?

Answer 9

• Decreased physical activity
• Decreased food intake
• Vasomotor control
  (arteriolar dilation increases delivery of blood to the skin)
• Sweating
  (sympathetic cholinergic response)
• Behavioural responses
  (increased surface area, removing clothing, moving to shaded area)

Question 10

How does Fever arise?

Answer 10

• 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 -> caused by local production of prostaglandins by cyclo-oxygenase in the hypothalamus
• > explains why aspirin and paracetemol reduces fever (inhibits COX enzyme)
• Body temperature regulates around a higher than normal body temp (analogy of a thermostat which has been reset)
• Mild fever = beneficial
• Severe fever = dangerous