BIOL 1361 1nd Edition Lecture 21Outline of Last Lecture I. ConductionII. ConvectionIII. RadiationIV. EvaporationV. Regulating Heat ExchangeVI. BioenergeticsVII. OsmoregulationVIII. OsmolarityIX. Osmotic ChallengesX. Marine AnimalsXI. Terrestrial AnimalsXII. Metabolic WasteOutline of Current LectureI. ExcretionII. Metabolic WasteIII. Excretory ProcessesIV. Excretory SystemsV. Kidney AnatomyThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.VI. Kidney FunctionCurrent LectureI. Excretiona. Ridding body of metabolic wasteII. Metabolic Wastea. Protein and nucleic acid breakdown NH3i. NH3 + H+ NH4+b. Ureai. Synthesized from NH2 by vertebrate liverii. Less toxic than NH3iii. Requires less H2O to excrete than NH3iv. Mammals, adult amphibians, sharks, some marine fishc. Uric Acidi. Low toxicityii. Excreted as pasteiii. Conserves H2Oiv. Birds, reptiles, insects, land snailsd. Fig 32.16i. Protein and nucleic compounds are broken down III. Excretory Processesa. Occur across a transport epitheliumi. A thin layer of cells with a large surface areaii. Usually in a network of tubulesiii. Step 1: Filtration 1. Occurs across the transport epitheliumiv. Step 2: Reabsorption1. Goes outside networkv. Step 3: Secretion1. Goes inside networkvi. Step 4: Excretion1. Leaves networkb. Step 1: Filtrationi. Body fluid enters epithelial tubuleii. Only small molecules cross membraneiii. Cells, large proteins cannot crossc. Step 2: Reabsorptioni. Selective recovery of valuable solutes1. Glucose2. Salts3. Vitamins4. Amino acidsii. Wastes left in filtrated. Step 3: Secretioni. Selective transport of ions or other substances into filtrate1. Filtrate – body fluid that has been modified by filtration, reabsorption and secretione. Step 4: Excretioni. Filtrate leaves the bodyIV. Excretory Systemsa. 2 main functions:i. Osmoregulationii. Excretion of metabolic wasteb. Protonephridiai. Figure 32.18Protonephridia(flat worm)Metanephridia(earthworm)Malpighian Tubules(grasshoppers)KidneysFiltration Body fluid enterstubule by cilia beatingBody fluid enterstubule by cilia beatingNo Blood plasma enters tubule due to pressureSecretion No From hemolymph to filtrateFrom blood plasma to filtrateReabsorption From filtrate to body fluidFrom filtrate to capillariesFrom rectum to hemolymphFrom filtrate to capillariesOsmoregulation Yes Yes Yes YesN-waste excretionNo Yes Yes Yes V. Kidney Anatomya. Figure 32.19b. Nephron – tube with walls one cell thicki. Surrounded by a capillary networkii. Filters bloodiii. Reabsorbs ions and H2Oiv. Secretes metabolic wastec. Glomerulus – capillary network above the nephroni. Network of capillaries at the influx end of a nephrond. Bowman’s Capsule – top end (influx end) of nephronVI. Kidney Functiona. Filtrationi. Blood pressure in the glomerulus pushes fluid and small molecules into Bowman’s capsuleb. Reabsorption and Secretioni. Selective permeability differs along nephron1. Reabsorbs Na+, Cl-, HCO3-, glucose, aa’s, water*2. Secretes K+ and H+ into filtratec. Excretioni. Filtrate enters renal pelvis and flows down ureter to
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