This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Osmoregulation in Animals evolutionary return to sea water presented new osmoregulatory problems because the fish were/are hypotonic to sea water (ca. 300 mOsm vs. 1050 mOsm of salts) osmotic outflow of water diffusional gain of NaCl osmoregulatory solutions increase in blood salt concentration to about 400 mOsm, to reduce the osmotic and ionic gradients, but still are hypotonic the teleost (bony fish) solution drink sea water to balance osmotic loss, but also adds more salt to the blood 1 to conserve water, urine flow is very low , and the urine is isotonic to the blood-- therefore kidney not the site of net salt excretion 2 excretion of salt is by active transport (extrusion) in the gills the shark solution increase blood NaCl (500 mOsm) and other salts to a total of about 600 mOsm, and add two organic solutes, urea (400 mM) and trimethylamine oxide (TMAO; 100 mM) , to make total blood concentration about 1100 mOsm, slightly hypertonic to sea water 1 therefore gain water osmotically, don't have to drink sea water, and can have fairly high urine flows 2...
View Full Document