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Excretory: Disposal & Osmoregulation

Excretory: Disposal & Osmoregulation. Excretion: Disposal of nitrogen-containing wastes Osmoregulation: Control of gain and loss of water and solutes Osmoregulation based largely on regulating solutes Water follows the movement of solutes by osmosis. Excretion: Aquatic Animals.

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Excretory: Disposal & Osmoregulation

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  1. Excretory: Disposal & Osmoregulation • Excretion: Disposal of nitrogen-containing wastes • Osmoregulation: Control of gain and loss of water and solutes • Osmoregulation based largely on regulating solutes • Water follows the movement of solutes by osmosis

  2. Excretion: Aquatic Animals • Animals must dispose of nitrogenous waste • Metabolism produces nitrogenous wastes from breakdown of proteins and nucleic acids • Most aquatic animals dispose of their nitrogenous wastes as ammonia • Highly soluble in water • Diffuses rapidly across cell membranes

  3. Excretory: Saltwater Fish

  4. Excretion: Land Animals • Land animals convert ammonia to less toxic compounds • Can be safely stored and transported in the body • Released periodically by excretory system • Requires energy for conversion • Different adaptations and type of reproduction determine excretion as urea or uric acid

  5. Excretory: Disposal & Osmoregulation • Urea • Excreted by mammals, most amphibians, sharks, and some bony fishes • Can be stored in concentrated solution but requires water for disposal • Uric acid • Excreted by birds, reptiles, insects, some amphibians • Excreted as solid paste for water conservation • Uses more energy for excretion

  6. Excretory

  7. Excretory: Waste • Protein and nucleic acid breakdown - nitrogen-containing wastes toxic by-products of • Ammonia poisonous but soluble and easily disposed of • Urea less toxic, easy to store and excrete • Some land animals save water by excreting a virtually dry waste

  8. Excretory: Waste in Urine • Urea – from amino acid breakdown • Uric Acid – from nucleic acid breakdown • Creatinine – muscle metabolism waste product

  9. Excretory System • The excretory system • expels wastes • regulates water and salt balance • Two human kidneys each contain ~ million nephrons • Urine leaves kidneys via ureters • Stored in urinary bladder

  10. Excretory Systen

  11. 1 Proximal tubule Bowman’s capsule Glomerulus Arteriolefrom renalartery Capillaries 3 Arteriolefrom glomerulus Distaltubule • Each nephron: folded tubule and associated blood vessels Branch ofrenal vein Fromanothernephron Collectingduct 2 Loop of Henlewith capillary network • Nephrons extract filtrate from blood • Refine filtrate into much smaller amount of urine D. DETAILED STRUCTURE OF A NEPHRON Figure 25.9D

  12. Proximal tubule Distal tubule Bowman’s capsule H2O H2O Nutrients NaCI HCO3 – HCO3 – NaCI Blood LE 25-11 K+ Some drugs and poisons H+ H+ Filtrate composition H2O Cortex NaCI Collecting duct Medulla HCO3 – H+ Loop of Henle Urea NaCI Glucose Amino acids NaCI Some drugs H2O Reabsorption Urea Secretion NaCI H2O Urine (to renal pelvis)

  13. Excretory: Filtration • Filtration (Bowman’s capsule) • Blood pressure forces water and many solutes from blood (glomerulus) into nephron

  14. Excretory: Reabsorption / Secretion • Controlled secretion of H+ and reabsorption of bicarbonate ions help regulate blood pH • Secretion also includes active transport of drugs and poisons • Reabsorption of salts and urea allow osmotic reabsorption of water

  15. Excretion: Reabsorption / Secretion • PROXIMAL TUBULE – always reabsorb glucose and amino acid - sometimes water, sodium, potassium, calcium depending on need • Secretion urea, creatinine, ions, drugs and toxins

  16. Excretory: Reabsorbing Water • LOOP OF HENLE - much water reabsorbed via active transport of salt • salt concentration in kidney higher in medulla • Longer loop – more water conservation (desert animals)

  17. Excretory: Reabsorption/Secretion • DISTAL TUBULE • specialized “Urine fine tuning” • Aldosterone hormone – increases amount of sodium reabsorbed into blood (water follows)

  18. Excretory: Water Reabsorption in Collecting Duct • Water reabsorbed • ADH (antidiuretic hormone) – cause collecting walls to be permeable to water to be reabsorbed • Caffeine interferes with ADH (dehydration)

  19. Excretory: Regulates Blood Pressure • Releases RENIN when blood pressure low - enzyme that causes production of chemical (angiotensin II) to constrict blood vessel - Angiotensin II increase aldosterone production

  20. Excretory: Dialysis

  21. Homeostasis: Liver • It assists the kidneys by • making urea from ammonia • breaking down toxic chemicals

  22. Liver • Blood from intestines flows through the liver before distribution to the rest of the body • Allows liver to adjust blood’s chemical content

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