ventilation and gas exchange in fish Flashcards
what is the mouth also known as
the buccal cavity
what happens when fish opens its mouth
-it lowers the buccal floor
-increases the volume in the mouth
-decreases the pressure
-water rushes in
what happens when fish closes its mouth
-it raises the buccal floor
-decreases the volume and increases the pressure in the mouth
-water is forced over the gills and out of operculum
gill structure (components)
-gill arch
-gill filaments
-lamellae
what are lamellae
additions to gill filaments which increase the surface area for gas exchange
what process do fish use to absorb the maximum amount of oxygen from the water into their blood as possible
counter current flow
why is the blood constantly encountering water with a higher concentration of oxygen in it
blood flows towards the gills where the fresh water with lots of oxygen in it has entered the fish
how are the gills adapted
-large surface area to volume ratio
-permeable membranes
-thin cells (squamous like)
-good vascular supply
what does permeable membranes help with
-allow gas to diffuse through tissues
what does the large surface area to volume ratio allow
-more diffusion of gases
what is parallel flow
-blood and water moving in the same direction
-oxygen rich blood is in contact with oxygen rich water and vise versa
why is counter current flow more effective than parallel
-maintains the steep concentration gradient
what’s the problem with parallel flow
-at first 02 moves down conc grad into blood
-very quickly reaches equilibrium and gas exchange no longer occurs
-despite lots of exchange surface still available
what is counter current flow
-blood and water flowing in opposite directions
-never reaches equilibrium as the gradient will always favour water to blood
how does counter current flow resolve the issues presented with parallel flow
-keeps oxygen poor blood always in contact with water that has a higher conc of oxygen in it
-helps maintain a steep concentration gradient
