Counter Current Heat Exchange

Question 1

What is counter current heat exchange?

Answer 1

Is the exchagne of heat between two fluid flowing in opposite directions in vessels that are in close proximity.

Question 2

Why don’t marine animals have fur?

Answer 2

Water compresses fur pushing air out and fur is not very hydrodynamic.

Question 3

How does blubber prevent heat loss?

Answer 3

It is a poor conductor of heat. Fat has very little blood flow as it has a low oxygen requirement. This makes skin cooler, reducing the heat gradient between it and the water. Reduces heat loss by conduction.

Question 4

What are 4 examples of organisms with counter-current heat exchange?

Answer 4

1. Penguin legs.
2. Flippers in seals, sea lions and whales.
3. Great white sharks.
4. Artic foxes and wolves.

Question 5

Outline the 5 steps of blood flow without counter-current heat exchange.

Answer 5

1. Artery and vein not touching.
2. Arterial blood flowing to the foot loses some heat to surrounding tissues.
3. Large difference between foot temperature and ambient temperature means a high rate of heat loss.
4. Venous blood returning to the core loses some heat to surrounding tissue,
5. Venous blood temperature is will below core temperature therefore most energy is used to reheat blood to 37 degrees.

Question 6

Outline the 6 steps of blood flow with counter-current heat exchange.

Answer 6

1. Artery and vein touching.
2. Arterial blood loses heat to venous blood.
3. Cooler arterial blood means the difference between foot temperature and ambient temperature is less which means there is a lower rate of heat loss.
4. Foot temperature kept slightly above ambient temperature.
5. Venous blood returning to the core is warmed by the arterial blood.
6. Venous blood is almost back to core temperature therefore little energy is required to reheat blood to 37 degrees.