Skin and Temperature Control

Question 1

What is normal body temperature?

Answer 1

37 degrees Celsius +/- 0.5 degrees

Question 2

Man is homeothermic. What does this mean?

Answer 2

We can tightly regulate body temperature

Question 3

What happens if body temperature rises over 41?

Answer 3

Proteins start to denature

Question 4

What happens if body temperature falls below 30?

Answer 4

Lose consciousness

Question 5

What are some factors which can cause variation within body temperature?

Answer 5

External temperature
Activity
Circadian rhythm
Menstrual cycle

Question 6

How is core temperature maintained?

Answer 6

By balancing heat loss and gain

Question 7

Radiation plays a role in thermal balance. Does it cause us to lose or gain heat?

Answer 7

Both!
If you took all your clothes off, you would be losing heat via radiation
If you were sunbeathing, you would gain heat from the rays

Question 8

Evaporation plays a role in thermal balance. Does it cause us to lose or gain heat?

Answer 8

Lose

->via respiration and sweating

Question 9

Conduction plays a role in thermal balance. Does it cause us to lose or gain heat?

Answer 9

Both!

->this is to do with heat transfer between touching objects e.g. hot water bottle, sleeping on a cold floor

Question 10

Convection plays a role in thermal balance. Does it cause us to lose or gain heat?

Answer 10

Both

->can lose heat via wind or water chill but plays a role in heating of radiators hence how we can gain heat too

Question 11

Which specialised neurons detect changes in body temperature?

Answer 11

Thermoreceptors

Question 12

At what temperature is the peak firing rate of cold receptors?

Answer 12

25 oC

Question 13

At what temperature is the peak firing rate of warm receptors?

Answer 13

40 oC

Question 14

Where is the body are peripheral thermoreceptors located?

Answer 14

Skin, especially in the face and the scrotum

Question 15

Where is the body are central thermoreceptors located?

Answer 15

Spinal cord
Abdominal organs
Hypothalamus

Question 16

Which part of the brain is responsible for maintaining internal body temperature?

Answer 16

Hypothalamus

Question 17

How does the body respond to cold stress be generating heat?

Answer 17

Increases metabolic rate
‘Futile’ muscular activity to produce heat e.g. jumping around to warm up
Shivering thermogenesis
Non-shivering thermogenesis (note this is only significant in infants due to brown adipose tissue)

Question 18

How does the body respond to cold stress be reducing the amount of heat lost by the body?

Answer 18

Vasoconstriction
Behavioural responses e.g. adding more clothing

Question 19

What happens in vasoconstriction?

Answer 19

Sympathetic arteriolar constriction reducing the delivery of blood to the skin

Question 20

Hypothermia?

Answer 20

A fall in deep body temperature to below 35 oC

Question 21

Who is at increased risk of hypothermia?

Answer 21

Neonates- less fat
Elderly- less mobile
Homeless people
Cold store workers
Outdoor pursuits

Question 22

What is the treatment of cold stress?

Answer 22

Dry/insulate to prevent further heat loss
Slow re-warming with bags or blankets
Internal re-warming with hot drinks
Rapid re-warming by immersion in water

Question 23

What happens as a consequence of cold stress?

Answer 23

Frost bite in the extremities

Question 24

What occurs vascularly in frostbite?

Answer 24

Vasoconstriction
Increase in viscosity
Promotes thrombosis
Causes anoxia

Question 25

What occurs cellularly in frostbite?

Answer 25

Ice crystals form in the extracellular space Increase in extracellular osmolality Movement of water from intracellular space Cell dehydration and death

Question 26

Why is there increased mortality rates in winter?

Answer 26

Increased MIs and stroke as there is increased vasoconstriction and blood viscosity

Question 27

How is the body's heat production minimised?

Answer 27

Decreased physical activity Decreased food intake

Question 28

How does the body increase the amount of heat it loses?

Answer 28

Vasodilation Sweating Behavioural responses e.g. taking off a jumper

Question 29

What happens in sweating to lose heat?

Answer 29

Sympathetic cholinergic fibres increase evaporative heat loss

Question 30

What are some consequences of heat stress?

Answer 30

Heat exhaustion Heat stroke

Question 31

At what body temperature does heat exhaustion occur?

Answer 31

37.5-40 oC

Question 32

What does heat exhaustion result in?

Answer 32

Vasodilation and drop in central blood volume

Question 33

What is heat exhaustion caused by?

Answer 33

Disturbance of the body's fluid/salt balance due to excessive sweating

Question 34

What are some of the symptoms of heat exhaustion?

Answer 34

Headache Confusion Nausea Profuse sweating Clammy skin Tachycardia Hypotension Weak pulse Fainting Collapse

Question 35

At what body temperature does heat stroke occur?

Answer 35

>49oC

Question 36

What are some of the symptoms of heat stroke?

Answer 36

Hot dry skin- sweating stops Circulatory collapse

Question 37

Soooo.... if heat exhaustion progresses, what can occur?

Answer 37

Heat stroke

Question 38

Who is more at risk of heat stress?

Answer 38

Neonates Elderly People during physical work in hot, humid environment's Workers wearing non-breathable protective clothing e.g. firefighters

Question 39

What is the treatment of heat stress?

Answer 39

Moving to a cool environment Remove clothing Fan Sponge with tepid water Give fluids, either orally or intravenously

Question 40

What is fever caused by?

Answer 40

Endogenous pyrogens (IL-1, IL-6)

Question 41

What happens by these endogenous pyrogens to cause fever?

Answer 41

Local production of prostaglandins by cyclo-oxygenase in the hypothalamus ->aspirin and paracetamol reduce fever as inhibit cyclo-oxygenase

Question 42

Why do you feel cold and shivery at the start of a fever?

Answer 42

I find this interesting :) The pyrogens shift the set point at which the body deems to be normal temperature. Therefore, when trying to reach this new high temperature, the body thinks it's cold so shivers to try and generate heat

Question 43

Which mechanism allows heat loss through our blood?

Answer 43

Convection -> This is where blood is warmed up in the core, goes out to the periphery where the heat can be lost then comes back to the core to be heated up again.

Question 44

What happens to the firing rate of cold receptors in response to a decrease in temperature?

Answer 44

Cold receptors increase their firing rate ->The opposite is true for heat receptors which increase their firing rate in response to an increase in temperature.