Ch. 44 Warm-Up Draw and label the parts of a nephron. What are the 4 main functions of a nephron? Where does each function in #2 above occur in a nephron? In the glomerulus, which substances are filtered? Which substances remain in the blood?
Controlling the Internal Environment Chapter 44
What you must know: Three categories of nitrogenous waste, which animal groups produce each, and why. The components of a nephron, and what occurs in each region. How hormones affect water balance by acting on the nephron.
Osmoregulation: control solute concentrations and balance water gain/loss Excretion: removal of nitrogenous wastes from body Types of Nitrogenous Wastes: Ammonia – water soluble, very toxic; aquatic animals Urea – produced by liver; less toxic, conserves water; most vertebrates Uric acid – excreted as paste or crystals; birds & reptiles
Types of Nitrogenous Wastes
Various forms of excretory systems Protonephridia - Platyhelminthes (Planaria) Metanephridia - Annelida Malpighian tubules – Insects, arthropods Kidneys - Vertebrates
How to make urine: Water and solutes enter filtrate; blood cells and proteins remain in body fluid. Reclaim glucose, vitamins, hormones Add toxins and excess ions 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 absorbed Descending loop of Henle: reabsorb water Ascending loop of Henle: reabsorb salt Distal tubule: K+ and NaCl levels regulated Collecting duct: filtrate becomes more concentrated; minimize water loss
From blood filtrate to urine SECRETION FILTRATION REABSORPTION EXCRETION
Hormones Antidiuretic Hormone (ADH): urine concentration, reduce H2O loss Also called vasopressin Renin/angiotensin II: raise blood pressure Aldosterone: Na+ reabsorption, H2O retention, blood volume, pressure
Blood Pressure Regulation
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