6.3: Gas exchange in fish

Question 1

What does cavity mean?

Answer 1

Cavity means open space

Question 2

There are how many gill filaments in each gill?

Answer 2

There are hundreds of gill filaments in each gill

Question 3

There are hundreds of gill filaments in each gill and gill filaments are what?

Answer 3

There are hundreds of gills in each gill filament and gill filaments are stacked up

Question 4

There are hundreds of gill filaments in each gill and gill filaments are stacked up.
Gill filaments are what?

Answer 4

Gill filaments are feather-like

Question 5

There are hundreds of gill filaments in each gill and gill filaments are stacked up.
Gill filaments are feather-like.
There are lots of what on each gill filament?

Answer 5

There are lots of lamellae on each gill filament

Question 6

There are hundreds of gill filaments in each gill and gill filaments are stacked up.
Gill filaments are feather-like.
There are lots of lamellae on each gill filament.
What do lamellae do?

Answer 6

Lamellae increase the surface area of the gills

Question 7

Why do fish need an exchange surface?

Answer 7

Fish need an exchange surface, because they have a small SA:V ratio

Question 8

Where do fish get their oxygen from?

Answer 8

Fish get their oxygen from the water

Question 9

What is the exchange surface for fish called?

Answer 9

The exchange surface for fish is called gills

Question 10

Fish have a what outer covering?

Answer 10

Fish have:
1. A waterproof
2. Therefore a gas-tight
outer covering

Question 11

Fish have a waterproof and therefore a gas-tight outer covering.
Being relatively large, they also have a small SA:V ratio.
Their body surface is therefore not adequate to supply and remove their respiratory gases and so, like insects and humans, they have evolved a specialised internal gas exchange surface - gills.
Where are the gills located?

Answer 11

The gills are located within the body of the fish, behind the head

Question 12

Fish have a waterproof and therefore a gas-tight outer covering.
Being relatively large, they also have a small SA:V ratio.
Their body surface is therefore not adequate to supply and remove their respiratory gases and so, like insects and humans, they have evolved a specialised internal gas exchange surface - gills.
The gills are located within the body of the fish, behind the head.
What are gills made up of?

Answer 12

Gills are made up of gill filaments

Question 13

The structure of the gills:
The gills are located within the body of the fish, behind the head.
Gills are made up of gill filaments.
The gill filaments are stacked.
At right angles to the gill filaments are gill lamellae, which increase the surface area of what?

Answer 13

At right angles to the gill filaments are gill lamellae, which increase the surface area of the gills

Question 14

The structure of the gills:
The gills are located within the body of the fish, behind the head.
Gills are made up of gill filaments.
The gill filaments are stacked.
At right angles to the gill filaments are gill lamellae, which increase the surface area of the gills.
Water is taken in through the mouth and forced where?

Answer 14

Water is taken in through the mouth and forced:

1. Over the gills
2. Out through an opening on each side of the body

Question 15

The structure of the gills:
The gills are located within the body of the fish, behind the head.
Gills are made up of gill filaments.
The gill filaments are stacked.
At right angles to the gill filaments are gill lamellae, which increase the surface area of the gills.
Water is taken in through the mouth and forced over the gills and out through an opening on each side of the body, called what?

Answer 15

Water is taken in through the mouth and forced:
1. Over the gills
2. Out through an opening on each side of the body
,called the operculum flaps

Question 16

One side of the gills has gill filaments and the other side is the gill what with a what?

Answer 16

One side of the gills has gill filaments and the other side is the gill arch with a bony bar

Question 17

Why is countercurrent flow important?

Answer 17

Countercurrent flow is important for ensuring that the maximum possible gas exchange is achieved

Question 18

Countercurrent flow is important for ensuring that the maximum possible gas exchange is achieved.
If the water and blood flowed in the same direction (what), then far less gas exchange would take place?

Answer 18

If the water and blood flowed in the same direction (parallel flow), then far less gas exchange would take place

Question 19

The essential feature of the countercurrent exchange system is that the blood and the water that flow over the gill lamellae do so in opposite directions.
This arrangement means that:
1. Blood that is already well loaded with oxygen meets water, which has its what?

Answer 19

This arrangement means that blood that is already well loaded with oxygen meets water, which has its maximum concentration of oxygen

Question 20

The essential feature of the countercurrent exchange system is that the blood and the water that flow over the gill lamellae do so in opposite directions.
This arrangement means that:
1. Blood that is already well loaded with oxygen meets water, which has its maximum concentration of oxygen.
Therefore, what takes places?

Answer 20

Therefore, diffusion of oxygen from the water to the blood takes place

Question 21

The essential feature of the countercurrent exchange system is that the blood and the water that flow over the gill lamellae do so in opposite directions.
This arrangement means that:
1. Blood that is already well loaded with oxygen meets water, which has its maximum concentration of oxygen.
Therefore, diffusion of oxygen from the water to the blood takes place.
2. Blood with little oxygen in it meets water that has had most, but not all, of its oxygen removed.
Again, what takes place?

Answer 21

Again, diffusion of oxygen from the water to the blood takes place

Question 22

The essential feature of the countercurrent exchange system is that the blood and the water that flow over the gill lamellae do so in opposite directions.
This arrangement means that:
1. Blood that is already well loaded with oxygen meets water, which has its maximum concentration of oxygen.
Therefore, diffusion of oxygen from the water to the blood takes place.
2. Blood with little oxygen in it meets water that has had most, but not all, of its oxygen removed.
Again, diffusion of oxygen from the water to the blood takes place.
As a result, what is maintained across the entire width of the gill lamellae?

Answer 22

As a result, a diffusion gradient for oxygen uptake is maintained across the entire width of the gill lamellae

Question 23

The essential feature of the countercurrent exchange system is that the blood and the water that flow over the gill lamellae do so in opposite directions.
This arrangement means that:
1. Blood that is already well loaded with oxygen meets water, which has its maximum concentration of oxygen.
Therefore, diffusion of oxygen from the water to the blood takes place.
2. Blood with little oxygen in it meets water that has had most, but not all, of its oxygen removed.
Again, diffusion of oxygen from the water to the blood takes place.
As a result, a diffusion gradient for oxygen uptake is maintained across the entire width of the gill lamellae.
In this way, about what % of the oxygen available in the water is absorbed into the blood of the fish?

Answer 23

In this way, about 80 - 90% of the oxygen available in the water is absorbed into the blood of the fish

Question 24

The essential feature of the countercurrent exchange system is that the blood and the water that flow over the gill lamellae do so in opposite directions.
This arrangement means that:
1. Blood that is already well loaded with oxygen meets water, which has its maximum concentration of oxygen.
Therefore, diffusion of oxygen from the water to the blood takes place.
2. Blood with little oxygen in it meets water that has had most, but not all, of its oxygen removed.
Again, diffusion of oxygen from the water to the blood takes place.
As a result, a diffusion gradient for oxygen uptake is maintained across the entire width of the gill lamellae.
In this way, about 80 - 90% of the oxygen available in the water is absorbed into the blood of the fish.
If the flow of water and blood had been in the same direction (parallel flow), the diffusion gradient would only be maintained across what?

Answer 24

If the flow of:

1. Water
2. Blood had been in the same direction (parallel flow), the diffusion gradient would only be maintained across part of the length of the gill lamellae

Question 25

The essential feature of the countercurrent exchange system is that the blood and the water that flow over the gill lamellae do so in opposite directions. This arrangement means that: 1. Blood that is already well loaded with oxygen meets water, which has its maximum concentration of oxygen. Therefore, diffusion of oxygen from the water to the blood takes place. 2. Blood with little oxygen in it meets water that has had most, but not all, of its oxygen removed. Again, diffusion of oxygen from the water to the blood takes place. As a result, a diffusion gradient for oxygen uptake is maintained across the entire width of the gill lamellae. In this way, about 80 - 90% of the oxygen available in the water is absorbed into the blood of the fish. If the flow of water and blood had been in the same direction (parallel flow), the diffusion gradient would only be maintained across part of the length of the gill lamellae and only what % of the available oxygen would be absorbed by the blood?

Answer 25

If the flow of water and blood had been in the same direction (parallel flow): 1. The diffusion gradient would only be maintained across part of the length of the gill lamellae 2. Only 50% of the available oxygen would be absorbed by the blood

Question 26

What are the parts of a fish called?

Answer 26

The parts of a fish are called the: 1. Mouth 2. Gill cover 3. Gills

Question 27

The parts of a fish are called the mouth, the gill cover and the gills. What is the other name for the gill cover?

Answer 27

The other name for the gill cover is the operculum

Question 28

What does the operculum do?

Answer 28

The operculum protects the gills

Question 29

What provide a large SA:V ratio in gills?

Answer 29

Lots of tiny feathery projections called lamellae provide a large SA:V ratio in gills

Question 30

What colour are the lamellae?

Answer 30

The lamellae are red

Question 31

The lamellae are red, why?

Answer 31

The lamellae are red, because of their incredibly rich blood supply

Question 32

What happens to the lamellae when they are out of the water?

Answer 32

The lamellae collapse down when they are out of the water

Question 33

In parallel flow, the blood and the water flow in the same direction. They would reach what?

Answer 33

They would reach equilibrium

Question 34

Countercurrent flow is important, because it maintains what throughout the gills and all of the gill lamellae?

Answer 34

Countercurrent flow is important, because it maintains a favourable concentration gradient throughout: 1. The gills 2. All of the gill lamellae

Question 35

Example of a highly active fish

Answer 35

An example of a highly active fish is mackerel

Question 36

How to highly active fish swim?

Answer 36

Highly active fish swim with their mouths open

Question 37

Highly active fish swim with their mouths open, why?

Answer 37

Highly active fish swim with their mouths open, because it keeps oxygen going into their gills

Question 38

Highly active fish swim with their mouths open, because it keeps oxygen going into their gills. What is this called?

Answer 38

This is called ram ventilation

Question 39

Gills have a rich what?

Answer 39

Gills have a rich blood supply