3.3.2.2 Gas Exchange - Fish

Question 1

Describe the surface of a fish

Answer 1

Water-proof, and therefore gas-tight, outer covering

Question 2

How does the fish surface relate to their gills?

Answer 2

They have a small SA:Vol and so their body aren’t adequte for removing their respiratory gases.

Question 3

Where are gills located?

Answer 3

At the back of the fishes head

Question 4

What are gills made from?

Answer 4

Gill filaments and they have Gill lamella which occur perpendicular to the filament.

Question 5

How does water flow through the fish?

Answer 5

Water is taken in through the mouth and then forced through the gills and then through the slits on the side

Question 6

In what direction does blood and water flow?

Answer 6

Oppisite directions which leads to the idea of countercurrent flow

Question 7

How does countercurrent work?

Answer 7

1. Water flows over the gills from the fish’s mouth and out through the gill openings.
2. Blood flows through the gill capillaries in the opposite direction of the water.

Because they’re flowing in opposite directions, water with a higher oxygen concentration is always next to blood with a lower oxygen concentration. This allows oxygen to continuously diffuse from the water into the blood along the entire length of the gill.

Question 8

Is countercurrent better or worse then parrallel flow?

Answer 8

Countercurrent is better and allows for 80–90% of the oxygen in the water to be absorbed