Excretory System - structure function

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Excretory System - structure function

  1. 1. Part 1 – Anatomy & PhysiologyMammalian Excretory System
  2. 2. Excretionremoval of metabolic wastedoes not include fecesfeces is what your body did not use, therefore notmetabolic waste
  3. 3. Vertebrate Excretory SystemHandles osmoregulation:Dispose metabolic wasteControl body fluid compositionaverage person loses 2L of liquids a daysuggested to consume 2L H2O / dayInvolves kidneys
  4. 4. Roles of Kidneyblood filtrationwaste excretionacid / base balanceblood pressure regulationhormone secretion
  5. 5. Mammalian KidneyA pairBean-shaped10 cm longBuilt of tubules and ductsthat carry urineContains a densenetwork of capillaries
  6. 6. Mammalian Kidney
  7. 7. Urine ExcretionKidneysUreter (duct)Urinary bladderUrethra (duct)Fig. 44.21
  8. 8. Urinesolution of metabolic wastewatersaltsorganic compoundsurea and uric acidother wastes / toxinsfluid for urine comes from filtered blood andextracellular fluid (ECF)
  9. 9. Urine ExcretionWhen ~200 mL of urine has collected in thebladder, the walls stretch and signals are sentto the brain.At ~600 mL, urine will involuntarily bereleased.
  10. 10. Urinary Tract Infection (UTI)Caused by bacterial growth in the urethra orbladderSymptoms:frequent urinationsensation of needing to urinate (even is there islittle to pass)blood in urinedischarge in urine (cloudiness)
  11. 11. Kidney Stonescrystallization of someurine solutesa 2 – 3 mm stone canobstruct flow to theureterTreatment:increased waterconsumptionsurgery
  12. 12. Internal Kidney Anatomyhttp://www.gisbornesc.vic.edu.au/home/jans/home/kidney.htmRenalmedullaRenalcortex
  13. 13. Kidney Structurerenal cortex: outside ofkidneyrenal medulla: middleof kidneyrenal pelvis: innerportion of kidney
  14. 14. Nephron AnatomyNephron: functional unitAbout a million nephrons make up thekidney.Fig. 44.21
  15. 15. Nephron AnatomyConsists of tubules/ductssurrounded by bloodvessels.Fig. 44.21
  16. 16. Activity1. Look at blood flowthrough the nephron(red & blue). Translateit into a flow chart.2. Look at the flow offiltrate through thetubules (yellow) of thenephron. Translate itinto a flow chart.
  17. 17. Blood Flow in KidneyBlood supply: renal arteryand veinBlood enters kidney throughrenal arteryrenal arteries stem from theaortaFiltered blood exits kidneythrough renal veinrenal veins flow into theinferior vena cavahttp://www.taguig.com/newitem/kidney.jpg
  18. 18. Blood Flow in NephronRenal arteryAfferent arterioleCapillaries of glomerulusEfferent arteriolePeritubular capillariesVasa rectaRenal vein
  19. 19. Blood Vessels in the NephronVessels LocationAfferentarterioleFrom renal artery to glomerulus.Capillaries ofthe glomerulusCapillaries in the Bowman’s capsule.EfferentarterioleCapillaries converge. Exitglomerulus.PeritubularcapillariesSurrounds proximal and distaltubules.Vasa recta Surrounds loop of Henle.Countercurrent. To renal vein.
  20. 20. Excretory SystemOverviewFiltration of bloodReabsorption ofvaluable substancesSecretion of toxins andexcess ionsExcretion of thecontents of tubuleFig. 44.17
  21. 21. FiltrationFiltering bloodBlood pressure forces fluidthrough filterTransport epithelium acts asfilterMovement of substances:Capillaries of glomerulus lumen of Bowman’s capsuleFiltrate = portion that isinside tubules
  22. 22. ReabsorptionMovement of substances:filtrate  interstitial fluid bloodThus reabsorbed back into the bodyProtein transporters movenutrients into interstitial fluid andbloodReabsorption saves us fromhaving to continuously replenishour body with fluidUrine is 4x more concentratedthan blood
  23. 23. SecretionMovement of substances:blood interstitial fluid  filtrateThus materials will eventually beexcreted from bodyOpposite of reabsorptionProtein transporters move wastesfrom blood to interstitial fluid tonephronSubstances removed:Nonessential or excess solutesWastetoxins
  24. 24. ExcretionExit of filtrate out ofbodyFiltrate is now calledurine
  25. 25. Pathway of Filtrate in kidneyBowman’s capsuleProximal tubuleLoop of HenleDistal tubuleCollecting ductFig. 44.21
  26. 26. Filtrate & Blood flowPathway of filtrate Function Blood vesselBowman’s capsule Filtration Capillaries ofglomerulusProximal tubule Reabsorption& secretionPeritubularcapillariesLoop of Henle Reabsorption Vasa RectaDistal tubule Reabsorption& secretionPeritubularcapillariesCollecting Duct Reabsorption& excretion
  27. 27. 1. Bowman’sCapsule Activetransport Passivetransport
  28. 28. 1. Bowman’s CapsuleGlomerulus: ball ofcapillariesBowman’s capsule: blindend of tubule thatsurrounds glomerulusNutrients flow fromglomerulus intoBowman’s capsule dueto high blood pressureflow (65 mm Hg; normal~ 25 mm Hg)Fig. 44.21
  29. 29. Glomerulus & Bowman’s Capsule
  30. 30. 1. Bowman’s CapsuleRetain large molecules (cells,protein etc.)Filter is non-selective for smallmoleculesContains waterContains small solutes: salt, sugar,amino acid, nitrogenous wastewater and dissolved solutes leaveglomerulus; enter Bowman’scapsulewaterNa+H+Cl-glucoseamino acidsvitaminsmineralsureauric acid
  31. 31. FiltrationSolute Bowman’sCapsulewater YesNaCl YesH+YesHCO3- Yesglucose Yesamino acids Yesvitamins / minerals Yesurea / uric acid Yesplasma proteins Nored blood cells Noplatelets No
  32. 32. 2. ProximalTubule
  33. 33. 2. Proximal TubuleSelective reabsorption of nutrientsinto capillaries (peritubular)Active transport (need transporters) ofvaluable nutrients (glucose, amino acids,vitamins) and salt (NaCl)Passive transport of water by osmosispH determined by:HCO3- reabsorptionH+ and NH3 secretionSecretion of drugs and other poisonsHCO3-, K+Na+, Cl-H2Oamino acidsglucosevitaminsH+, NH3
  34. 34. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwaterNaClH+HCO3-glucoseamino acidsvitamins / mineralsurea / uric acid
  35. 35. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwater RNaCl RH+SHCO3- Rglucose Ramino acids Rvitamins / minerals Rurea / uric acid S
  36. 36. 3. Loop of Henle:Descending limb
  37. 37. H2O3. Loop of Henle:Descending LimbTransport epithelium is only permeable towaterImpermeable to salt and other small solutesReabsorption of water by osmosisInterstitial fluid is hyperosmoticOsmolarity of interstitial fluid becomesprogressively greater from outer cortex to innermedullaFiltrate becomes more concentrated as itmoves down into the medulla
  38. 38. Things to keep in mindWhat is the mechanism that maintains theosmolarity difference in the nephron?What keeps the osmolarity of the interstitialfluid to become progressively greater fromthe outer cortex to the inner medulla?
  39. 39. 4. Loop of Henle:Ascending limb
  40. 40. NaCl4. Loop of Henle:Ascending LimbTransport epithelium is permeable tosalt but not waterThin segment: NaCl passive transport Diffusion possible due to concentratedfiltrate Increases osmolarity of the inner medullaThick segment: NaCl active transportFiltrate becomes more dilute as itmoves up towards the cortex
  41. 41. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwater RNaCl RH+SHCO3- Rglucose Ramino acids Rvitamins / minerals Rurea / uric acid S
  42. 42. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwater R R (desc)NaCl R R (ascn)H+SHCO3- Rglucose Ramino acids Rvitamins / minerals Rurea / uric acid S
  43. 43. Urine ConcentrationFig. 44.23
  44. 44. CountercurrentFlow Flow of filtrate in theloop of Henle and flowof blood in the vasarecta are in oppositedirections Allows the lessconcentrate filtrate tobe next to the lessconcentrated blood(and vice versa) Contributes toestablishing theosmotic gradient Increase the efficiencyof reabsorptionhttp://www.austincc.edu/apreview/NursingPics/RenalPics/Picture25.jpg
  45. 45. 5. DistalTubule
  46. 46. 5. Distal tubuleRegulates K+ and NaCl concentrations bycontrolling active transport of:K+ secretionNaCl reabsorptionContributes to pH regulationsecretion of H+reabsorption of bicarbonate (HCO3-)
  47. 47. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwater R R (desc)NaCl R R (ascn)H+SHCO3- Rglucose Ramino acids Rvitamins / minerals Rurea / uric acid S
  48. 48. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwater R R (desc) RNaCl R R (ascn) RH+S SHCO3- R Rglucose R Ramino acids R Rvitamins / minerals R Rurea / uric acid S S
  49. 49. 6. CollectingDuct
  50. 50. 6. Collecting DuctCollects from several nephronsCarries filtrate from medulla to renalpelvisUrine formation by concentratingfiltrateRegulates amount of NaCl in urineReabsorption of NaCl by active transportEpithelium is permeable to water but notto saltNaClureawater
  51. 51. 6. Collecting duct Duct is permeable to urea only in innermedulla Urea can diffuse out to the interstitial fluiddue to high urea concentration in filtrate Contribute to hyperosmotic environment Drives reabsorption of water by osmosis any urea and urine that is reabsorbedis less than that was filtered intonephron Filtrate becomes increasinglyconcentrated Enables conservation of water
  52. 52. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwater R R (desc) RNaCl R R (ascn) RH+S SHCO3- R Rglucose R Ramino acids R Rvitamins / minerals R Rurea / uric acid S S
  53. 53. Nutrient FlowSolute ProximaltubuleLoop ofHenleDistaltubuleCollectingductwater R R (desc) R RNaCl R R (ascn) R RH+S SHCO3- R Rglucose R Ramino acids R Rvitamins / minerals R Rurea / uric acid S S R
  54. 54. Urine ConcentrationFig. 44.23
  55. 55. Video Summarizing FunctionReview of excretory system http://www.youtube.com/watch?v=WtrYotjYvtU (12:21,start at 2:54 for focus on kidney)

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