The kidneys


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A powerpoint on the kidneys, covering the edexcel B3 revision topic.

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The kidneys

  1. 1. The KidneysEdexcel Revision
  2. 2. The Urinary System• All cells produce a number of waste products!These waste products diffuse back into theblood. (E.g. Carbon Dioxide and Urea).• The Urinary system produces, stores and thenremoves Urine from the body.• The major organ is the Kidney.
  3. 3. Kidney Failure• Kidney Failure is a serious medical conditionwhere the kidney’s are unable to filter thewaste products from the blood.• Symptoms include vomiting, diarrhoea,nausea and frequently concentrated urine orfrequently under concentrated urine.• Kidney failure can be caused by restriction ofblood flow to the kidney’s or high amounts oftoxins. Other conditions such as diabetes orhigh blood pressure can also cause it.
  4. 4. Treatment• Treatments for kidney failure include;• A kidney transplant. Because humans havetwo kidney’s, you can donate a single kidneyand still be able to filter the blood efficiently.• Kidney dialysis. Kidney dialysis treats kidneyfailure patients by removing small amounts ofa patients blood and filtering it beforereturning it back into the body.
  5. 5. A dialysis machine looks like this.
  6. 6. The kidney• Made up of two important tissues.• Blood vessels take the blood through thekidney where unwanted substances end up intiny convoluted tubes.• The tubes eventually join to form a single tubecalled the Ureter.• The Ureter leaves the kidneys to go to thebladder.
  7. 7. • There are 3 stages in the working of thekidney!1.Filtration of the blood. The water and othermolecules are squeezed out of the blood intothe tubules.2.Selective reabsorbtion of the usefulsubstances back into the blood. Byosmoregulation, the amount of water in theblood is controlled and kept constant.3.Excretion of waste. Excess water, ions and theurea pass to the bladder in the form of urineand are then released from the body.
  8. 8. Structure of the Nephron• The nephron is the functional unit of thekidney, and millions of them surround eachkidney.• The nephrons drain into a collecting ductwhich then release urine into one tube (theureter) before draining away the urine to thebladder.
  9. 9. The effect of ADH on blood watercontent• The amount of water reabsorbed by thekidneys during selective reabsorbtion iscontrolled by the hormone ADH.• The hormone ADH is produced by thepituitary gland in the brain.• The hormone affects the permeability of thekidney tubules.
  10. 10. • The role of ADH in the kidney is an example ofnegative feedback.• Negative feedback is where a substance isproduced that opposes a change to a system,such as high salt concentration. If negativefeedback continues then a system willeventually turn back to normal. You can seenegative feedback in other areas of the body,including in the menstrual cycle.