BIO 102 Lecture Notes - Lecture 20: Malpighian Tubule System, Renal Pelvis, Distal Convoluted Tubule
17 Apr 2017
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Document Summary
Urinary systems - organ systems that produce and eliminate urine. Urine - a watery fluid containing a variety of substances that have been filtered from the blood or from the interstitial fluid that bathes all cells. Ions and nutrients in excess of the body"s needs. The primary cellular wastes in urine are the nitrogen-containing compounds (nitrogenous wastes): Nitrogenous wastes are formed when cells break down the amino acids liberated by protein digestion. The liberated amino groups (-nh2) are released by the cells as ammonia (nh3), which is toxic. Ammonia is the primary nitrogenous waste of freshwater organisms. Terrestrial animals that collect and store their urine convert ammonia into less toxic urea or uric acid (in birds, reptiles, and insects) They use diffusion and active transport through cell membranes into the surrounding water to excrete cellular wastes and maintain homeostasis. The urinary systems in flatworms act primarily to maintain water balance. Those in more complex invertebrates at as filters that:
