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  2. 2. Excretion: is the removal of waste products of metabolism formed inside cells WASTE
  3. 3. What happens if wastes remain inside a cell? Accumulation ofWASTE wastes leads to death.
  4. 4. Animals excrete:1. Carbon dioxide + water from: respiration2. Urea, uric acid or ammonia from: deamination In which organ does deamination occur? Liver Which material is broken down to produce urea? Excess proteins
  5. 5. Deamination: breaking down excess amino acids AMINO ACID is broken into two: Part with The rest isnitrogen forms: used for energy AMMONIA UREA
  6. 6. Animals excrete:3. Bile pigments from: decomposition of old and worn out red blood cells Iron in haemoglobin is stored Remaining part of haemoglobin = bile pigments
  7. 7. Plants excrete:1. CO2 and H2O from: respiration2. O2 from: photosynthesis3. Various wastes: when leaves or bark are shed Bark peels off
  8. 8. Four mammalian excretory organs:1. LUNGS  excrete CO2  lose water vapour2. KIDNEYS  excrete salts, water and nitrogenous products
  9. 9. Four mammalian excretory organs:3. SKIN  excretes salts, some urea and water4. LIVER  excretes bile pigments
  10. 10. Functions of the kidney1. excretion  removes urea2. osmoregulation  keeps the blood at a constant concentration
  11. 11. Kidneys have a homeostatic functionHomeostasis – keeping a constant internal environment
  12. 12. Internal environment: conditions around cells
  13. 13. Question: SEP, 2012The kidneys play an important role inhomeostasis. Explain this homeostatic roleplayed by the kidneys. (3)Remove urea from the blood. Urea is a waste ofmetabolism that must be eliminated from thebody.Help keep a constant concentration in the bloodby controlling the amounts of water and salts.
  14. 14. Kidneys areattached to the back
  15. 15. External structure of a Pig Kidney
  16. 16. Model of the urinary system Renal artery Adrenal glandRenal vein Kidney Aorta UreterVena cava Urethra
  17. 17. Give three differences between the ureter & the urethra.1. Muscular2. Longer3. Leads urine to bladder
  18. 18. The bladder holds between 400–500 cm3 of urine wall is elastic and has muscle tissue
  19. 19. Bladder contracts to expel urine
  20. 20. Fig. 2 Vertical section through a kidney. Cortex Medulla Renal artery Renal vein Pelvis Ureter
  21. 21. Give six differences betweencomponents found in the renal artery and the renal vein.Renal artery Renal vein1.
  22. 22. Give six differences betweencomponents found in the renal artery and the renal vein.Renal artery Renal vein1. More O2 Less2. Less CO2 More3. More urea Less4. More glucose Less5. More salts Less6. More water Less
  23. 23. Section through a kidney Renal artery branches into many arteriolesPelvis: urinecollects here; thenflows into ureter
  24. 24. Arterioles continue to branch inside a kidney to form capillariesAORTA A knot of capillaries = glomerulus pelvis
  25. 25. Human excretory system
  26. 26. Bowman’s nephron capsule glomerulusNephron:a filtering unit
  27. 27. Each kidney contains a CORTEX million MEDULLA nephrons
  28. 28. A nephron consists of a Bowman’s capsuleleading into a long tubule.
  29. 29. Glomerulus: a knot of capillaries Afferent Efferent arteriole arteriole Bowman’s capsule glomerulus glomerular Proximal convoluted filtrate tubule
  30. 30. Ultrafiltration is filtration under pressure the heart provides pressure occurs in the Bowman’s capsule
  31. 31. Components of glomerular filtrate:GlucoseAmino acidsVitaminsIonsNitrogenous wasteSome hormonesWater
  32. 32. Why are no proteins found in urine? Too large to be filtered out of the glomerulus
  33. 33. What would you conclude, if proteinsand red blood cells are found in urine. Kidneys are damaged.
  34. 34. Efferent Pressure in arteriole Afferentglomerulus can arteriole be increased by: Dilating the afferent arterioles Constricting the efferent arterioles
  35. 35. Useful materials in the glomerular filtrate must be REABSORBEDGlucoseAmino acidsVitaminsIonsWater
  36. 36. All the glucose & amino acids are reabsorbed in the:Most of the water is reabsorbed in the: Loop of Henle
  37. 37. The length of the loop of Henle variesaccording to amount of water in habitat. Which kidney belongs to the animal living in the desert? A B C
  38. 38. BEAVER(abundant RABBIT SAND RAT water) (moderate water) (scarce water)
  39. 39. Selective reabsorption in the proximal convoluted tubuleIn humans:Glomerular filtrate production: 125 cm3 min-1Urine production: 1 cm3 min-1 125 cm3 100 cm3 24 cm3 Urine 1 cm3
  40. 40. Microscopic slice of kidney tissueBlood pressure forces tissue fluid out of a clumpof narrow capillariesThe fluid contains urea, salts, glucose and othersoluble substancesThe fluid trickles down this tubule and the usefulsubstances such as glucose are reabsorbed into theblood In this tubule more or less water is reabsorbed to maintain the blood concentration Excess water, some salts and urea collect here before passing to the bladder as urine
  41. 41. QUESTION: SEP, 2012The nephron plays an important role inosmoregulation in humans. The following are themain parts of the nephron.Bowman’s capsule; proximal convoluted tubule; Loopof Henle’; distal convoluted tubule and collectingduct.a) Draw a labelled diagram to show the structure of the nephron. Label the main parts clearly. (4)b) Give the function of the Bowman’s capsule and the Loop of Henle’. (4)
  42. 42. What must a person do ifhe/she suffers from kidney failure?
  43. 43. Theartificial kidney: Dialysismachine
  44. 44. Why does blood move out of the patient through an artery?
  45. 45. Fig. 6 The kidney machine.
  46. 46. Explain why total kidney failure is fatal if left untreated.The kidney filters wastes like urea from thebloodstream.If wastes remains in the blood, they build upand disturb the internal balance.Death results as accumulated wastes act aspoisons.
  47. 47. Question:A kidney transplant is a more permanenttreatment for kidney failure. Give TWO reasonswhy a patient may be treated with dialysisinstead of a transplant.i) No compatible kidney available / waiting list is longii) Not strong enough for operation / operation has its risks
  48. 48. Water Balance LOSS GAIN1. Sweating 20% 1. In Drinks 60%2. Breathing 16% 2. In Food 28% out3. In faeces 4% 3. Metabolic 12% water4. In urine 60% metabolic water is water formed by chemical reactions such as respiration
  49. 49. A kangaroo rat lives in the desertand never drinks water. List two ways of how it can get water.
  50. 50. Mention three ways how the valuesshown would change on a hot day.
  51. 51. 1. Less urine2. More sweat3. More beverages
  53. 53. Osmoregulation is the process of regulating the amount of water and salts to keep a constant blood concentration the kidneys therefore have a homeostatic function
  54. 54. ADH: Antidiuretic hormone Released by: pituitary gland When:  blood becomes concentrated Result:  more water reabsorbed from kidney ADH makes you feel thirsty
  55. 55. ADH is released when sensory receptors: kidney detect a low level of water in blood
  56. 56. Insufficient waterHypothalamusdetects a lowlevel of water inblood. Pituitary gland secretes ADH. Increased thirst. ADH causes nephron to Urine reabsorb water. becomes concentrated.
  57. 57. Excessive water intake Hypothalamus detects a highlevel of water in blood. Pituitary gland stops secreting ADH/ less is produced. Nephron Urine reabsorbs less becomes water. dilute.
  58. 58. Water regulation is an example of: NEGATIVE FEEDBACK :  a change from the normal level is detected and corrective mechanisms act in the opposite direction to cancel the change
  59. 59. Negative feedback is importantto keep conditions inside body
  60. 60. Good thing we reached THE END