Excretory system regulation

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Excretory system regulation

  1. 1. Part 2 - RegulationMammalian Excretory System
  2. 2. Three Effects of UrineOsmolarity: solute concentrationBlood Pressure: pressure on the blood vesselsdue to pumping of bloodAlso relates directly to blood volumepH Balance
  3. 3. Hormones in kidney functionExcretory system is regulated by theendocrine system (hormones used forhomeostasis)ADH: antidiuretic hormoneregulates osmolarityRAAS: renin-angiotensin-aldosterone systemregulates blood pressure and volumeANF: atrial natriuretic factorregulates blood pressure and volume
  4. 4. Response to high bloodosmolarityFig. 44.24a
  5. 5. Negative Feedback on HighOsmolarityOsmoreceptor onhypothalamusPituitary glandrelease ADHIncreasedreabsorptionSensationof thirstHighOsmolarityDrink
  6. 6. Antidiuretic hormone (ADH)A short peptide hormoneProduced by the hypothalamusStored in posterior pituitary glandHormone is readily available rather than waitingfor the entire process of transcription / translation
  7. 7. Hypothalamus & Pituitaryhttp://www.juniordentist.com/wp-content/uploads/2012/09/Pituitary-gland-anatomy.jpg
  8. 8. ADH ProductionStimulus: increase blood osmolarityDetection by osmoreceptors in hypothalamusSends signal to pituitary to release ADHTarget: distal tubule, collecting ducts
  9. 9. Effects of Antidiuretic hormone(ADH)It’s in the nameDiuresis: increased urinationAnitdiuretic:opposes diuresisLess urinationRetain water
  10. 10. Effects of ADHIncrease sensation of thirstincrease volume of water in body / bloodIncrease permeability of epithelium to waterincrease water reabsorption into body / bloodDirect effect:dilution of blood  lowers blood osmolaritySide effect:reduces volume of urinemore concentrated urineless frequent urination
  11. 11. OsmolarityWhat type of situation would cause increasedosmolarity?Water loss:SweatingDehydrationDiarrhea
  12. 12. DiureticsInhibit the release of ADHEffect:less reabsorption of waterIncreased urine outputExamples: Alcohol and coffee
  13. 13. Diabetes InsipidusCause: deficiency in ADHEffect: Inability of kidneys to conserve waterSymptoms:Dilute urine, frequent urinationExcessive thirstTreatment:Drinking sufficient waterTake ADH medicationNot the same as diabetes mellitus: urine does notcontain glucose and is not sweet
  14. 14. Response to low blood pressureand low blood volumeFig. 44.24b
  15. 15. Negative Feedback on LowBlood PressureJGA secreteReninAdrenal glandrelease AldosteroneIncreasedreabsorptionConstriction ofblood vesselsLow BloodPressureAngiotensinogen  Angiotensin II
  16. 16. Blood PressureQ:What part of the kidney would be mostdirectly affected by low blood pressure?A: Glomerulus: high blood pressure neededfor filtration
  17. 17. Blood PressureStimulus: low blood volume and pressureDetected by juxtaglomerular apparatus(JGA)Juxta(position) = next toreceptors next to the glomerulusnear the afferent arterioleSecretes enzyme renin
  18. 18. Renin-angiotensin-aldosteronesystem (RAAS)Renin catalyzes:angiotensinogen angiotensin IIAngiotensinogen onlyactive when neededConstitutively producedBut activated by enzymecleavage
  19. 19. Effects of Angiotensin IIBlood vessel constriction increase blood pressureStimulate release ofaldosterone
  20. 20. AldosteroneReleased from adrenalglands (located abovekidneys)Target: distal tubules
  21. 21. Effects of AldosteroneIncrease reabsorption of NaCl in proximaltubuleIncreases reabsorption of waterIncreases blood volumeIncrease blood pressure
  22. 22. Blood PressureWhat type of situation would cause adecrease in blood pressure?Water loss:SweatingDehydrationdiarrheaBlood loss (bleeding out)Low salt diet
  23. 23. Fig. 44.24
  24. 24. Atrial natriuretic factor (ANF)Peptide hormoneLocation: from walls of atria in heartStimulus: increased blood volume andpressureEffect:Inhibits NaCl reabsorption (antagonistic toaldosterone)  decrease water reabsorption decrease blood volume / pressureInhibit renin, reduce aldosterone release
  25. 25. Negative Feedback on HighBlood PressureAtria releaseANFReabsorptionReninHigh BloodPressureAldosterone
  26. 26. Comparing Excretory HormonesADH RAAS ANFStimulusCauseEffect onreabsorptionEffect onblood vessels
  27. 27. Comparing Excretory HormonesADH RAAS ANFStimulus HighosmolarityLow bloodpressure / volumeHigh bloodpressure / volumeCause Water loss Water lossLow salt dietBlood lossWater retentionHigh salt dietEffect onreabsorptionIncreased Increased DecreasedEffect onblood vesselsConstriction
  28. 28. Water ReabsorptionWhy would you need 2 different sets ofenzymes (ADH & RAAS) for the same finaleffect (increased reabsorption)?
  29. 29. pH BalanceHow do living systems regulate the amountof acid / base in their systems?buffers – conjugate acid-base pairsHCl Cl- + H+
  30. 30. pH Balanceconversion of CO2 to other compounds helpregulate blood pHH2O + CO2 H2CO3 HCO3- +H+HCO3- is reabsorbed in the proximal anddistal tubulescarbonic acid carbonate ion
  31. 31. QuestionsHow does blood osmolarity affect blood volume?How does blood osmolarity affect blood pressure?How does blood volume relate to blood pressure?If the blood vessels are exhibiting low bloodpressure, what can you do to the blood volume to fixthe problem?When could a decrease in blood volume NOTcorrelate to an increase in blood osmolarity?

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