BIOL 125 Lecture Notes - Lecture 9: Osmotic Concentration, Tonicity, Stenohaline
2 Feb 2017
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Document Summary
Ammonium, nh4 add a h+ to nh3, common in freshwater fish; exchanged for na+ in freshwater fish. Urea: mammals, adult amphibians, many marine fish, turtles; relatively non-toxic, can be concentrated; requires less water than ammonia; require more energy and h2o to produce from nh4. Uric acid: found in land snail, insects, spiders, birds and many reptiles, relatively mon-toxic, largely insoluble in h2o -> less h2o removed, more energy costing than urea, related to mode of reproduction. Osmosis: diffusion of h2o across a selectively permeable membrane down a concentration gradient. Osmolarity: molarity multiplied by the # of particles. Human blood is about 300 mosm/l and seawater is about 1,000 mosm/l. Hypertonic: more dissolved solutes outside the cells, cells will shrink. Hypotonic: lower dissolved solutes inside the cells, cells with burst. Hypoosmotic regulators: surrounding having higher osmolarity compared to them, h2o wants to flow out of them. Problems: retaining h2o and get rid of salt.
