B6A10OsmoregX - Metanephridial Excretory System...

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Unformatted text preview: 11/8/11 Metanephridial Excretory System • Pericardium • Coelom • Heart • Nephrostome • Kidney • Nephridiopore • Gill • Mantle cavity Mollusc Ultrafiltra4on of hemolymph across thin wall of cardiac atrium into pericardial coelom Paired nephrostomes draw coelomic fluid into metanephridia tubules consolidated into kidney •  Excre4on via nephridiopore into mantle cavity •  •    Probably not homologous to annelid metanephridia (annelid origin = mesoderm; mollusk origin = ectoderm) •  Metanephridial Excretory System Aqua4c Mollusc (clam) •  Hemolymph drawn by afferent vein to gill (ctenidium)   Lose ammonia to water flowing through the mantle cavity •  Hemolymph con4nues from gill by efferent vein to atrium of heart     Water and small solutes permeate into pericardial (coelom) fluid Cells, respiratory pigments, and proteins retained in hemolymph, pumped by ventricle to arteries •  Coelomic fluid drawn into tubules via ciliated nephrostomes   Essen4al solutes reabsorbed by kidney •  Excre4on via nephridiopore into mantle cavity   Swept away via excurrent siphon 1 11/8/11 Mammal Renal Excretory System Nephron: func4onal unit of the vertebrate kidney –  Tubule + associated capillary beds   Nephron structure: hUp://www.youtube.com/watch?v=aQZaNXNroVY&NR=1   Nephron func>on: hUp://www.youtube.com/watch?v=glu0dzK4dbU&feature=related Osmolality of fluid along nephron •  Red = water restric4on •  Blue = high water intake 2 ...
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