BIOD33H3 Lecture Notes - Lecture 7: Osmotic Shock, Teleost, Heart Rate
Document Summary
Major problem for marine fish: higher osmolality in outside water than inside body: water constantly leaving. Salty water in gut, tends to draw water out of body fluid. Ions from the water diffuse into the body. They actively pump the ions they drink into their bodies. This leaves behind freshwater (to be absorbed in gut via osmosis) Largely takes place in the esophagus, as well as stomach. Substantial increase in sodium-proton exchangers: exchange sodium for hydrogen ions. Use gills to pump ions out into the seawater. Chloride cell (mitochondrial-rich cells) of the gills. Nak atpase pumps sodium from cytosol into the blood plasma. Nkcc uses sodium gradient established to allow sodium to come in, bringing potassium and 2 chlorides. Get a build up of chloride in the chloride-rich cells. On the seawater side, there is a chloride channel (cftr), which is how chloride exit out the cell into the sea water: pumped chloride from plasma into sea water.
