Respiratory system in fish

Question 1

What difficulties are there to overcome and what challenges animals that get their oxygen from air and fish?

Answer 1

animals that get their oxygen from water don’t need to try and prevent water loss

water is 1000x more denser than air

and has a lower oxygen content

scales do not allow for gaseous exchange i

t is more energy efficient for the water to move in one direction, rather than pumping it in and out of lungs-like respiratory organs

Question 2

What are the organ for gas exchange in bony fish and how are they effective?

Answer 2

gills

large sa

good blood supply

thin layers

Question 3

What are the features of the gills?

Answer 3

protected by the operculum (bony flap)

which also is active in maintaining water flow over the gills

gill filaments occur in large stacks (gill plates)

and are separated by water which exposes a large surface area

Question 4

What is the problem with this method of exchange and how does this affect some fish?

Answer 4

fish require constant water movement over the gills

in primitive cartilaginous fish such as sharks and sting rays rely on continual movement, known as ram ventilation

Question 5

What extra adaptations do gills have to ensure the most effective gas exchange occurs?

Answer 5

tips of adjacent gill filaments overlap - increase resistance of water over the gills and slows it down so there is more time for gaseous exchange to take place

water moving over the gills and the blood in the gill filaments flow in different directions.

Sets up a countercurrent exchange system and increases the concentation gradient more effective than a parallel system

Question 6

What happens when the mouth is open and the opercular valve is closed?

Answer 6

-mouth is opened,

floor of buccal cavity lowered

increases volume and pressure drops

and water moves into it

opercular cavity containing the gills expands lowers pressure in the opercular cavity containing the gills

floor of buccal cavity moves up, increases the prssure so water moves from the buccal cavity over the gills

Question 7

What happens when the mouth closes and the opercular valve opens?

Answer 7

operculaum opens and the sides of the opercular cavity move inwards

all these actions increase the pressure in the opercular cavity and force water over the gills and out of the operculum

the floor of the buccal cavity is steadily moved up; this maintains a flow over water over the gills

Question 8

How are the gills adapted for efficient gas exchange?

Answer 8

1. short diffusion distance between blood and water
2. blood maintains a diffusion gradient
3. faster diffusion of O2 / CO2

Question 9

explain

Answer 9

• b
• blood enters at the furthest distance along gill plate, therefore at min
• blood exits at the start of the gill plate therefore at max
• water exists gill plate at min after doing a lot of exchange
• water enters gill plate at max after coming in with a fresh supply