Fish ventilation

How are gills adapted?

Thin walls for exchange- shorter distance for diffusion, increasing speed/rate, good blood supply, overlapping filaments, filaments and lamellae increase surface area

Describe inspiration clearly in steps

1) Mouth opens, operculum is closed

2) buccal cavity floor is lowered

3)Increases volume and decreases pressure of buccal cavity compared to outside

4)Water rushes into the mouth down a pressure gradient (due to 3)

Describe exhalation in steps

1) Buccal cavity floor is raised

2) Pressure inside buccal cavity is higher than in opecular cavity

3) water moves from buccal cavity over the gills into the opecular cavity

4)mouth is now closed and operculum opens

5)sides of operculum cavity move inwards increasing the pressure

6)water rushes out of the fish through the operculum

Where are gills located?

Contained in the gill cavity, covered by protective operculum

What is each gill arch attached to?

2 stacks of filaments, on the surface of each filament is there are rows of lamellae

What does the lamellae consist of?

A single layer of flattened cells that cover a vast network of capillaries

What are some adaptations of gills?

Rich blood supply (steep conc gradient), thin=short diffusion distance, filament and lamallae make a SA:V ratio

How are overlapping gill filaments an adaptation?

Increase water resistance, so slower flow, so more time for gas exchange

What’s a counter current?

By having blood flow in the opposite direction, the gradient is always such that the water has more available oxygen that the blood and the oxygen diff continues after the blood has more then 50% of the waters oxygen content

how is countercurrent exchange system useful?

when the concentration of oxygen in the water is low at the opercular cavity end of the

lamella, blood has just entered the gill lamella, therefore, is even lower in oxygen

concentration. This means there is still a diffusion gradient allowing the diffusion of oxygen

from the water into the blood

What would happen with concurrent flow?

Conc of oxygen in the blood in the gills and in the water will equalise, so no more oxygen exchange will occur