Skin and Temperature Control

Question 1

What is our core body temperature?

Answer 1

37 +/- 0.5 degrees

Question 2

What happens at 41 degrees?

Answer 2

Proteins start to denature

Question 3

What happens below 30 degrees?

Answer 3

Lose of concsiousness

Question 4

What does normal body temperature vary with?

Answer 4

• External temperature
• Activity
• Circadian rhythm
• Menstrual cycle

Question 5

How is core temperature maintained?

Answer 5

By balancing heat loss and heat gain

Question 6

What techniques does our body use to maintain thermal balance?

Answer 6

• Convection
• Conduction
• Evaporation
• Radiation

Question 7

How much do we lose to evaporation each day?

Answer 7

-Respiration + sweating
~600ml/day at rest
-But 4l/hour at extremes
loses 600kcal/l

Question 8

How much heat loss does radiation account for?

Answer 8

60%

Question 9

What is convection?

Answer 9

Fluid conduction which is important in blood

Question 10

What is conduction?

Answer 10

Heat transfer direct between touching objects

Question 11

How much heat do we produce at rest?

Answer 11

~80kcal/hour at rest

Question 12

How does our body detect body temperature?

Answer 12

Cold receptors and warm receptors

Question 13

Where are the peripheral thermoreceptors located?

Answer 13

Skin

-Especially face and scrotum

Question 14

Where are the central thermoreceptors found?

Answer 14

• Spinal cord
• Abdominal organs
• Hypothalamus

Question 15

What do the peripheral thermoreceptors detect?

Answer 15

Changes in environmental temperature

Question 16

What do the central thermoreceptors detect?

Answer 16

Changes in core body temperature

Question 17

Where do thermoreceptors send signals to?

Answer 17

Hypothalamic thermoregulatory center

Question 18

How is heat generated within the body in response to cold?

Answer 18

• General metabolism
• Voluntary muscular activity
• Shivering thermogenesis
• Nonshivering thermongenesis

Question 19

Why is nonshivering thermogenesis only significant in infants?

Answer 19

They have brown adipose tissue

Question 20

How is heat loss from the body reduced in response to the cold?

Answer 20

• Vasomotor control

- Behavioural responses

Question 21

Describe vasomotor control in response to the cold.

Answer 21

Sympathetic arteriolar constriction reduces delivery of blood to the skin

Question 22

What behavioural responses do humans have to the cold?

Answer 22

• Reducing surface area
• adding clothing
• Moving to warmer environment

Question 23

Hypothermia

Answer 23

A fall in deep body temperature to below 35 degrees

Question 24

Who is at risk of hypothermia?

Answer 24

• Neonates
• Elderly
• Vagrants
• Cold store workers
• Outdoor pursuits
• North sea workers

Question 25

Why are neonates at risk of hypothermia?

Answer 25

- Big surface area to volume ratio - Not much fat - Don't shiver well - But they do have brown adipose tissue

Question 26

Why are the elderly at risk of hypothermia?

Answer 26

- Do not detect temperature changes so well - Less shivering capacity - More immobile

Question 27

What is the treatment for hypothermia?

Answer 27

-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 28

Describe how vascular frostbite occurs.

Answer 28

- Vasoconstriction - Increase in viscosity - Promotes thrombosis - Causes anoxia

Question 29

Describe how cellular frostbite occurs.

Answer 29

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

Question 30

What is 'Winter mortality'?

Answer 30

40% excess mortality in winter in the UK

Question 31

Why does winter mortality occur?

Answer 31

- Partly due to increases in heart attacks and strokes following periods of cold weather - Increased vasoconstriction and increased blood viscosity contribute

Question 32

How is heat production minimised in response to heat?

Answer 32

- Decreased physical activity | - Decreased food intake

Question 33

How is heat loss increased in response to heat?

Answer 33

- Vasomotor control - Sweating - Behavioural Responses

Question 34

Describe vasomotor control in response to heat.

Answer 34

Arteriolar dilation increases delivery of blood to the skin

Question 35

How does sweating occur?

Answer 35

Sympathetic cholinergic fibres increase evaporative heat loss

Question 36

What behavioural response to humans have to heat?

Answer 36

- Increasing surface area - Removing clothing - Moving to shaded area

Question 37

Heat exhaustion (heat illness)

Answer 37

Body temperature raised in range 37.5-40 degrees

Question 38

What does heat exhaustion result in?

Answer 38

Vasodilation and drop in central blood volume

Question 39

What is heat exhaustion caused by?

Answer 39

A disturbance of the body's fluid/salt balance

Question 40

What are the symptoms of heat exhaustion?

Answer 40

- Headache - Confusion - Nausea - Profuse sweating - Clammy skin - Tachycardia - Hypotension - Weak pulse - Fainting and collapse

Question 41

Heat stroke (heat injury)

Answer 41

Body temperature raised above 40 degrees

Question 42

Why doe heat stroke occur?

Answer 42

Body temperature control mechanism fails

Question 43

What are the symptoms of heat stroke?

Answer 43

- Hot dry skin (sweating ceased) | - Circulatory collapse

Question 44

Who is most at risk of heat illness/injury?

Answer 44

- Neonates & the elderly - People doing physical work in hot humid environments - Workers wearing non-breathable protective clothing

Question 45

What is the treatment for heat illness/injury?

Answer 45

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

Question 46

What is fever?

Answer 46

Part of the body's mechanism for fighting infection

Question 47

What is fever caused by?

Answer 47

Endpgenous pyrogens (IL-1 and IL-6)

Question 48

What controls 'set point'?

Answer 48

Hypothalamus

Question 49

Why do aspirin and paracetamol reduce fever?

Answer 49

- Endogenous pyrogens shift the set point - Caused by local production of prostaglandins by cyclo-oxygenase in the hypothalamus - Explains why aspirin & paracetamol reduce fever

Question 50

What type of fever is beneficial?

Answer 50

Mild

Question 51

What type of fever is dangerous?

Answer 51

Severe