Physiology 7: Body temp

Question 1

What happens if body temp is too low?

Answer 1

Too low
- Slow metabolism
Inadequate O2 supply (molecules have less kinetic energy, lower O2 affinity)
Freezing of cells

Question 2

What happens if body temp is too high?

Answer 2

Too high
Proteins denature
Inadequate O2 supply (metabolic rate increases, tissue O2 requirement increases)
Membrane structure alterations
= geographical ranges of animals would be restricted to temp favourable regions

Question 3

What are the 4 heat exchange processes?

Answer 3

Radiation
Convection
Conduction
Evaporation

Question 4

Describe radiation

Answer 4

Without direct contact
In humans, 60% heat loss
E.g from the sun

Question 5

Describe convection

Answer 5

Air/fluid across body surface
15% heat loss

Question 6

Describe conduction

Answer 6

With direct contact
In humans, 3% heat loss

Question 7

Describe evaporation

Answer 7

Water from body surface
22% heat loss

Question 8

How to minimise heat loss through radiation in a cold environ

Answer 8

Decreasing SA:V
Layers of clothing

Question 9

How to minimise heat loss through convection in a cold environ

Answer 9

Layers of clothing
Sheltered from wind

Question 10

How to minimise heat loss through evaporation in a cold environ

Answer 10

Little exposed skin
Dry

Question 11

How to minimise heat loss through respiration in a cold environ

Answer 11

Cover mouth and nose, stops cold air from entering lungs

Question 12

larger animals have ______ SA:V so lose heat less quickly

Answer 12

smaller

Question 13

Describe ectotherms

Answer 13

Body temp fluctuates with environ
Temp conformers
Heat is derived from environ
E.g reptiles, amphibians

Question 14

What are ectotherms also known as

Answer 14

poikilotherms

Question 15

Give an example of an ecotherm

Answer 15

Reptiles, amphibians

Question 16

Describe endotherms

Answer 16

Constant body temp
Regulators
Heat derived from metabolism

Question 17

What are endotherms also known as

Answer 17

homeotherms

Question 18

Give an example of an endotherm

Answer 18

humans

Question 19

What are the benefits for ectotherms?

Answer 19

Metabolic rate is 5x slower than endo
Less energy = less food = less h20
Can devote large proportion of energy budget to reproduction
Good colonisers of poor arid environs

Question 20

What are the disadvantages for ectotherms?

Answer 20

No nocturnal environ niches (unless in tropical and summer temperate areas)
Cannot sustain high activity bursts as risks O2 debt
Anaerobic = lactate accumulation = fatigue
*

Question 21

What are the benefits for endotherms?

Answer 21

Can sustain high activity burst
Nocturnal activity
Able to exploit cooler environs
Forage widely and migrate over long distances

Question 22

What are the disadvantages for endotherms?

Answer 22

Require larger body sixes with lower SA:V
Metabolic rate 5x faster than ecto
*

Question 23

What are the 3 mechanisms for insulation?

Answer 23

Brown fat
Blubber
Fur/hair/feathers

Question 24

Describe brown fat

Answer 24

Brown fat (adipose tissue)
Specialised for rapid heat production

Question 25

Describe blubber

Answer 25

Thick vascularized adipose tissue under skin of sea mammals
Low thermal conductivity of skin, low metabolic activity

Question 26

What is the function of fur/hair/feathers

Answer 26

Reduces convection by trapping layer of warm air close to skin surface
Effect is lost if air is replaced by water

Question 27

Describe countercurrent heat exchanges

Answer 27

Blood in hot artery flows by colder veins and exchanges heat, so cold blood does not return to the heart

Question 28

Where are countercurrent heat exchanges found?

Answer 28

birds, tongues of whales, dolphins fins

Question 29

Describe the thermal neutral zone

Answer 29

→ above upper critical limit, body must expend energy to decrease body temp
→ lower critical ***
Hypothalamus = control centre for this

Question 30

What are the thermoregulatory processes below the lower critical limit?

Answer 30

Vasoconstriction
Shivering
Hormones
Brown adipose tissue

Question 31

Describe vasoconstriction

Answer 31

Diameter of blood vessels decreases
Blood flow to skin decreases
Skin cools
Less heat loss to environ through radiation, conduction and convection
Heat trapped in body core

Question 32

What is shivering?

Answer 32

Rapid contriction of skeletal muscles

Question 33

What are the hormones involved in the thermoregulatory processes below the lower critical limit?

Answer 33

Adrenaline
Thyroxine

Question 34

Describe how the brown adipose tissue is involved in the thermoregulatory processes below the lower critical limit

Answer 34

Rich in mitochondria = breakdown fuel into heat only
Usually broken down into energy and heat
Rich blood supply
Found in newborn mammals, hibernating mammals and the necks of human adults
Non-shivering thermogenesis

Question 35

What are the thermoregulatory processes below the upper critical limit?

Answer 35

Vasodilation
Perspiration
Panting

Question 36

Describe vasodilation

Answer 36

Diameter increases
Blood flow to skin increases
Skin heats up
***

Question 37

Describe hypothermia

Answer 37

if metabolic heat production cannot compensate for heat loss

Question 38

Describe hyperthermia

Answer 38

if evaporative cooling cannot counteract heat gain