gas exchange in fish Flashcards
how does ventilation occur in fish
-lower their buccal cavity and open their mouth; this increases the volume of the buccal cavity and therefore decreases the pressure. water then flows into the buccal cavity
-simultaneously the operculum valve will shut and the operculum cavity (where gills are) will expand
-this increases volume of operculum cavity and decreases the pressure
-the fish raise the floor of the buccal cavity forcing the water from the bucas cavity over the gills within the operculum cavity
-the fish closes it’s mouth and opens the operculum. this increases the pressure in the operculum cavity and forces water over the gills and out the size of the fish’s head so there’s a constant flow of water
what are gills made up of
gill filaments and gill lamellae
how do fish maximise gas exchange
-large surface area as there are many gill filaments and lamellae
-short diffusion distance as the gill lamellae and filaments are both thin and contain a capillary network
-maintain a steep concentration gradient by the countercurrent mechanism
what is the counter current flow mechanism
a mechanism used to maintain the steep concentration gradient for diffusion as water has a lower dissolved oxygen conc compared to the conc of oxygen in the atmosphere
how does the counter current flow mechanism work
water flows over the gill lamellae in the opposite direction to the flow of blood in the capillaries. This ensures that a diffusion gradient is maintained across the entire length of the gill lamellae
what size sa:v do fish have
a small SA:V
what is the lamallae
folds of the filament that increase surface area
features of bony fish gills
-have five pairs of gills
-theyre covered by the operculum
-each gill consists of two rows of filaments which are attached to a bony arch
-the filaments are very thin and their surface is folded into many secondary lamallae
