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Chapter 11 Excretion Lesson 3 - The 2 functions of kidneys and Kidney failure


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Chapter 11 Excretion Lesson 3 - The 2 functions of kidneys and Kidney failure

  1. 1. 2 Functions of kidneys <ul><li>Formation of urine (excretory function) </li></ul><ul><li>Osmoregulator </li></ul>
  2. 2. Kidneys as Osmoregulators <ul><li>Water potential of the blood must be kept relatively constant </li></ul>High Water Potential Red Blood Cells will burst Low Water Potential Cells and tissues becomes dehydrated and shrink (flaccid) Water enters cells Water leaves cells
  3. 3. Kidneys as Osmoregulators…. <ul><li>Water potential in blood is influenced by: - </li></ul><ul><li>Concentration of salts in plasma </li></ul><ul><li>Amount of water in plasma </li></ul>Therefore, the water potential is controlled by controlling the amount of water in the plasma via the kidney
  4. 4. Kidneys as Osmoregulators…. <ul><li>The amount of water/water potential is controlled by a hormone named: - </li></ul><ul><li>Vasopressin or Anti-diuretic hormone (ADH) </li></ul><ul><li>ADH is produced by the posterior pituitary gland </li></ul>
  5. 5. Kidneys as Osmoregulators…. <ul><li>ADH regulates the water reabsorption in the kidney tubules </li></ul>Secrete More ADH Loss of water from body Water potential decreases Kidney tubules reabsorb more water Less Urine is Produced Water Potential Returns to Normal Pituitary Gland
  6. 6. Kidneys as Osmoregulators…. Secrete Less ADH Large Intake of Water Water potential increases Kidney tubules reabsorb less water More Urine is Produced Water Potential Returns to Normal Pituitary Gland
  7. 7. Kidney Failure <ul><li>Several causes: </li></ul><ul><li>Diabetes </li></ul><ul><li>High blood pressure (hypertension) </li></ul><ul><li>Inherited kidney disease (linked to genetics) </li></ul><ul><li>Kidney stones </li></ul><ul><li>Infections </li></ul><ul><li>Abuse of painkilling drugs </li></ul>top 2 causes
  8. 8. Kidney Failure <ul><li>Diabetes </li></ul><ul><li>- A medical condition that keeps the body from utilising sugar in a normal manner. If sugar is not broken down, it acts as poison and damages the blood vessels in the kidney. </li></ul><ul><li>High Blood Pressure </li></ul><ul><li>- Can damage the small blood vessels in the kidneys. When this happens, the blood vessels cannot filter toxins from the blood. </li></ul>
  9. 9. The Dialysis Machine <ul><li>It is also known as “artificial kidney”. </li></ul><ul><li>It is used to cleanse the blood of a person whose kidneys do not work (one can survive with a kidney). </li></ul><ul><li>It eliminates the excess salts and nitrogenous waste from the patient’s blood. </li></ul>
  10. 10. How a Dialysis Machine Works (1) <ul><li>It consists of a long cellulose tube coiled up in a water bath. </li></ul><ul><li>Blood from an artery in the arm of the patient flows through the tubing in the dialysis machine. </li></ul><ul><li>(Note: Tubing is partially permeable to allow diffusion of small molecules (e.g. urea) into the dialysis fluid. </li></ul><ul><li>Tubing is narrow, long & coiled to increase surface area: volume ratio -> speeds up rate of exchange of substances ) </li></ul>
  11. 11. How a Dialysis Machine Works (2) <ul><li>The dialysis tubing is bathed in dialysis fluid contains essential salts for the body. </li></ul><ul><li>A diffusion gradient is set up so that the waste products diffuse from the patient’s blood into the dialysis fluid. </li></ul>
  12. 12. Scheme of partially permeable membrane during hemodialysis , where red is blood, blue is the dialysing fluid, and yellow is the membrane.
  13. 13. How a Dialysis Machine Works (3) <ul><li>The temperature of the dialysis fluid is maintained at body temperature. </li></ul><ul><li>The filtered blood is returned to a vein in the patient’s arm. </li></ul><ul><li>Patient needs to be treated 2-3 times a week & each treatment takes several hours. </li></ul>
  14. 14. Removal of CO 2 from the Lungs C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy Aerobic respiration diffuses into the blood plasma Carried in the form of “ hydrogen carbonate ions (HCO 3 - )” blood passes through the lungs hydrogen carbonate CO 2 + H 2 O convert In the Lungs, CO 2 concentration is low,
  15. 15. Removal of CO 2 from the Lungs hydrogen carbonate CO 2 + H 2 O convert diffuses out of the blood capillaries into the alveolar cavities for exhalation CO2 CO 2 O 2
  16. 16. Quiz
  17. 17. cortex renal artery renal vein pelvis ureter medulla