Excretion Ppt


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  • Excretion Ppt

    1. 1. What is Excretion? <ul><li>Excretion is the process of removing cellular wastes. </li></ul><ul><li>The term excretion refers specifically to the elimination of wastes produced by cellular activity. </li></ul><ul><li>It is not removal of undigested food material! </li></ul><ul><li> Goal: Maintain homeostasis!! </li></ul>
    2. 2. <ul><li>The most important waste products are CO2, nitrogen compounds, and salts . </li></ul><ul><li>CO2 – produced during cellular respiration (in addition to water) </li></ul><ul><li>Nitrogen compounds – (ammonia, urea, and uric acid) produced by the breakdown of amino acids (protein digestion) </li></ul><ul><li>Salts – produced by metabolism </li></ul>What is Excretion? (contd)
    3. 3. Why do we need to excrete Ammonia? <ul><li>All organisms produce ammonia as they metabolize nutrients (protein digestion) </li></ul><ul><li>Ammonia is a nitrogenous waste that is toxic and must be removed from the body </li></ul><ul><li>How an organism removes ammonia depends upon where it lives </li></ul>
    4. 4. <ul><li>Removing Nitrogenous Waste Products </li></ul><ul><li>(1) Ammonia (NH3): </li></ul><ul><li>Requires little energy </li></ul><ul><li>Ammonia is highly toxic! </li></ul><ul><li>This form of waste can only be used if the organism lives in an aquatic environment </li></ul><ul><li>Example: Paramecium, protists, some ocean fish </li></ul><ul><li>. </li></ul>
    5. 5. Removing Nitrogenous Waste Products <ul><li>(2) Urea: </li></ul><ul><li>- Many land animals and some bony fish (amphibians, mammals) dilute the toxic ammonia with water. </li></ul><ul><li>- This substance is called Urea & is filtered out by the kidneys. </li></ul><ul><li>- The problem is they do lose water in the process! </li></ul><ul><li>- Requires Energy </li></ul>
    6. 6. Removing Nitrogenous Waste Products <ul><li>(3) Uric Acid </li></ul><ul><li>Not very toxic because insoluble </li></ul><ul><li>Evolved as an adaptation of land animals </li></ul><ul><li>Many organisms try to conserve water & excrete their Nitrogen waste as a solid! (little loss of water is involved) </li></ul><ul><li>Examples: insects, reptiles, birds </li></ul>
    7. 7. The Mystery behind Bird Poop <ul><li>Unlike mammals, birds do not urinate. </li></ul><ul><li>Their kidneys extract nitrogenous wastes from the bloodstream, and excrete it in the form of uric acid. </li></ul><ul><li>Uric acid has a very low solubility in water, so it emerges as a white paste. </li></ul>
    8. 8. Human Excretion Where does excretion occur in humans? Like other animals humans have a system that excretes Nitrogen wastes as Urea, salt, and water Urinary System : Kidneys, ureter, urethra, and bladder Kidneys (located in back) play important role in homeostasis – - remove waste products from blood - maintain blood pH - control water content of blood
    9. 9. How The Kidneys Work <ul><li>Blood enters kidneys from renal artery </li></ul><ul><li>Blood is filtered by passing through millions of nephrons </li></ul><ul><li>Wastes pass through ureter to the bladder as urine </li></ul><ul><li>Clean blood returns to body through renal vein </li></ul><ul><li>Bladder stores urine and passes urine out of the body through the urethra </li></ul>
    10. 10. Nephrons: How the Body makes Urine <ul><li>Your kidneys are composed of 1 million cells called Nephrons. </li></ul><ul><li>These long coiled tubes are where the blood is actually filtered and urine is produced </li></ul>
    11. 11. The Nephron <ul><li>Nephron has three functions: </li></ul><ul><li>1. Glomerular filtration : filter out water, N-wastes (urea), salt, glucose, amino acids </li></ul><ul><li>2. Tubular reabsorption : reabsorb materials that the body still needs (food molecules, water). </li></ul><ul><li>3. Tubular secretion : collect wastes as urine and pass them to the bladder (urea, salts, other substances) </li></ul>Blood filters through the kidneys about 6 times a day. 99% of the water is reabsorbed and not excreted
    12. 12. Anatomy of 1 Nephron
    13. 14. Anatomy of 1 Nephron
    14. 15. What kinds of animals have the most efficient kidneys? <ul><li>Desert animals must be able to conserve moisture </li></ul><ul><li>Most terrestrial animals must drink fresh water often; however the kangaroo rat does not need to drink water very often – its kidneys absorb every little drop of water </li></ul>
    15. 16. Kidney Failure <ul><li>If renal failure occurs, </li></ul><ul><li>people must get their blood filtered through </li></ul><ul><li>Dialysis. </li></ul>
    16. 17. Gout Is a disease where the human body accumulates Uric acid in the joints. Heredity, alcohol & kidney failure lead to this problem.