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Osmoregulation and the Excretory SystemOsmoregulation: control solute concentrations and balance water gain/lossExcretion: removal of nitrogenous wastes from body Types of Nitrogenous Wastes:Ammonia – water soluble, very toxic; aquatic animalsUrea – produced by liver; less toxic, conserves water; most vertebratesUric acid – excreted as paste or crystals; birds & reptiles Various forms of Excretory Systems(ordered from least complex to most complex)Protonephridium: closed tubes lacking an internal opening capped by a cellular unit called flame bulb. Urine passes out of small pores.Metanephridia: internal openings collect body fluids into a long tube surrounded by capillaries. Urine exits out pores.Malpighian tubes: remove N waste from hemolymph, located near digestive tract. Secretes dry waste with feces.Kidneys: compact organs containing tubules surrounded by capillaries. Functions in water and blood filtration, excretion of N waste and salt How to make urine:Ø Water and solutes enter filtrate; blood cells and proteins remain in body fluid.Ø Reclaim glucose, vitamins, hormonesØ Add toxins and excess ionsØ Filtrate leaves body as urine Mammalian excretory system:Nephrons: functional units of the kidney• Glomerulus: filtrate forced into Bowman’s capsule.• Blood cells and proteins DO NOT enter filtrate Processing of Blood Filtrate:Proximal tubule: secretion & reabsorption change volume and composition of filtrate Bicarbonate, NaCl, water is absorbedDescending loop of Henle: reabsorb waterAscending loop of Henle: reabsorb saltDistal tubule: K+ and NaCl levels regulatedCollecting duct: filtrate becomes more concentrated; minimize water loss From blood filtrate to urine: filtration à secretion / reabsorption à excretion Hormones Antidiuretic Hormone (ADH): á urine concentration, reduce H2O loss Also called vasopressin Renin/angiotensin II: raise blood pressure Aldosterone: á Na+ reabsorption, á H2O retention, blood volume, pressure Blood Pressure regulation via hormones and altering the volume/ions Excretory organs: Urine exits kidney through Ureters Bladder: stores urine Urethra: urine exits body Believe it or not… Your kidneys are only 4 in long and weigh about 5 oz (weight of ½ unfinished can of pop) Usually we urinate 1.5-2.5 liters/day 44 gallons of blood is filtered by kidneys everyday-2 bathtubs full Fresh urine is cleaner than spit, cleaner than your hands after they have been washed and cleaner than the sandwich you will eat for lunch Gandhi drank urine every day (Tantric Yoga practice) Gladiators brushed their teeth with it Colonial housewives cleaned their home with it 1st football=pig bladder
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