Biology: Gas Exchange: Fish Flashcards
Outline the structure of a fish’s gas exchange system
-each gill from thin plates called gill filaments -gill filaments attached to bony gill arch
-gill filaments covered in tiny folds called lamellae -lamellae have lots of capillaries and thin layer of cells
Why are gill filaments important?
create large surface area for water to flow over
Why are gill lamellae important?
further increases surface area
How does water flow over the gills?
in opposite direction to blood , countercurrent flow
State the principles of concurrent flow
-water and blood over lamellae in same direction -water high oxygen concentration, diffusion
-concentration gradient decreases -equilibrium reached, no more diffusion
State the principles of countercurrent flow
-water and blood over lamellae in opposite directions -blood always in contact with water of high oxygen concentration, diffusion -occurs across entire length of lamella
What five adaptations are important in a fish’s gas exchange system?
-thin epithelium/walls of lamellae -large quantity of lamellae and filaments
-countercurrent flow mechanism -large quantity of capillaries around lamellae
-ventilation
Why are thin epithelium/walls of lamellae important?
short diffusion distance
Why is a large number of filaments and lamellae significant?
increases surface area
Why is countercurrent flow important?
maintains concentration gradient for diffusion
Why is it necessary for a large number of capillaries around the lamellae?
circulation constantly removes oxygenated blood, maintains steep concentration gradient
Why is ventilation in fish important for gas exchange?
ensure fresh flow of water over gills, maintains steep concentration gradient
Explain how ventilation works in fish
-mouth open, operculum shut -water into bucal cavity due to decreased pressure and increased volume -mouth close, operculum open -pressure increased, volume decreased
-water forced out over gills
