Exhange in bony fish

Question 1

What are bony fish?

Answer 1

= large organisms- small surface area to volume ratio- needs a specialised transport system
= active organisms- needs high demand of oxygen

Question 2

What is the first feature of a fish?

Answer 2

= scales
= prevents gases from diffusing through

Question 3

How do fish get oxygen from?

Answer 3

= from water
= concentration of o2 in water is lower than air
= have an evolved exhange system allows the maximum amount of oxygen from the water

Question 4

What is transported to the fish?

Answer 4

= oxgen-rich water enters the fish with the mouth
= water passes through gills
= in gills oxygen diffuses from the water into the blood
= carbon dioxide diffuses from the blood and into the water
= water passes out from the opercular opening
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Question 5

What is the 2nd feature of the fish?

Answer 5

= consists of gill arches- extending from these arches are pairs of gill filaments
= filaments are covered in gill lamelle- where gas exchange takes place
= water flows between gill lamelle
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Question 6

How are gill lamelle adapted for gas exchange?

Answer 6

= massive surface area for gases to difuse over
= short diffusion distance through the walls of the lamelle and into blood stream
= network of blood capillaries, when oxygen diffuses into blood it is carried away maintains steep concentration gradient
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Question 7

What is the counter current exchange system in the gill lamelle?

Answer 7

= blood with low concentration of oxygen passes into capillaries
= oxygen diffuses from the water into the blood
= oxygen rich blood now passes out of the gill lamelle and leaves the gill
= flow of blood is opposite direction of flow of water
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Question 8

What is an advantage of a counter-current exchange system?

Answer 8

= maintains a steep concentration gradient for oxygen
= always a concentration gradient for oxygen
= equaliberian is never reached
= 80% of oxygen in water diffuses into blood stream
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