BIOG 1440 Lecture 16: Excretion
12 May 2017
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Document Summary
Protein and nucleic acid metabolism produces nitrogenous waste. The liver of mammals and most adult amphibians converts ammonia to less toxic urea. Ammonia is released through the whole body surface. Urea is released in urine through the kidney. Uric acid is secreted as a paste. Excretory systems are variations on a tubular theme. Excretion is reabsorption by a filtration device. Filter body fluids, reclaim valuable solutes, reabsorb water, secrete wastes. Bean shape structure, connected to renal artery and vein (20% of cardiac output) Each kidney feeds urine into the bladder through the ureter. The kidney is an assembly of nephrons. Nephron basic unit of kidney 0. 4 to 1. 2 million per kidney. Many tubular elements interspersed with blood vessels. The filtrate is generated from blood in bowman"s capsule. Then progresses from proximal tubule to loop of henle, the distal tubule, and the collecting duct. Primary urine kidneys produce urine by refining a filtrate. Definitive urine primary urine is processed.
