features of gills for gas exchange
gill filaments over laps craeting testion with water and slowing down the currest if water going iver gills allowing for lobger time for gas exchange
blood flow and water flow in different directions allowing for a steep conc gradient and efficient diffusion COUNTERCURRENT EXCHANGE
adaptations of gills
gill lamelle have a rich blood supply and have large SA so are tge main site of gas exchange and maintenance of steep concentration gradient
gill fillanents lots of then abd need a flow of water to keep them apart allowing to expose the part where gas exchange happens
what happens when a fishes mouth is open
buccul cavity is lowered
increases volume pressure decrease
opperculum valve is shut
gills expand
bucal cavity moves up so pressure inside high and water moves over gills for high conc gradient
descibe tge parallel system
blood and water flow in same direction
steep initial O2 gradient
diffusion takes place until water and oxygen conc are equal
describe countercurrest systen
blood and water flow in opposite direction
conc if water and bloos is equal
oxygen flows down the gradient so higher amounts of oxygen in blood is achieved
