BIOL 125 Lecture Notes - Lecture 10: Malpighian Tubule System, Ascending Limb Of Loop Of Henle, Water Balance
20 Mar 2017
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L10 - ch42 water & electrolyte balance in animals. Diffusion - movement of particles from concentration to concentration. Osmosis - special case of diffusion, water from [water] to [water] across selectively permeable membrane. Hypertonic = hyperosmotic - more solute in solution. Hypotonic = hypoosmotic - less solute in solution. Marine birds - countercurrent system excrete salt from blood. Responds with osmoregulation to control [water & salt] in body. Osmoconformers - set point for [water] and [electrolyte] matches environment. Osmoregulators marine fish, tissues hypotonic to salt water - achieve homeostasis. 42. 2 water and electrolyte balance in aquatic environments. Ouabain - toxic to animals, prevents na+/k+ atpase from working. Epithelial cells that transport sodium & chloride ions are similar to membrane proteins in shark rectal gland. Marine birds/reptiles that drink salt water excrete nacl in nostrils. Cant be isosmotic , not enough salt in environment. Active pumping of ions is in different population of cells in seawater vs. freshwater.
