4.3 Fish Flashcards
Describe the adaptations of fish structure
Water is denser then air and more viscous only containing 5% oxygen
- gills have a large surface area and good blood supply the thin epithelium layer covers fish
- operculum protects gills
-lamella is the main site of gas exchange and has a large sa and a good capillary network layered by epithelial cells reducing the diffusion distance.
Describe how gas exchange occurs in fish
Floor of the buccal cavity lowered and mouth opens causing the volume to increase and the buccal pressure to increase forcing the operculum to open forces water to move through the mount into buccal cavity down a steep concentration gradient the opercular cavity would expand and the opercular valve remains closed increasing volume and decreasing pressure creating a pressure gradient and water moves from opercular cavity through the gills where gas exchange happens.
Water moves out of the fish when the mouth is closed and the floor of the buccal cavity is raised the opercular valve opens decreasing the volume increasing the pressure opercular cavity contracts pushing water through the operculum into external environment down a steep pressure gradient.
Explain counter current system
Where water flows over the gills and the blood in the gill filaments flow in the opposite direction maintaining a steep concentration gradient over the gill filaments.
