Renal Physiology (IV) - Osmoregulation(Urine Dilution & Concentration)

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by dr Mohammed Abel Gawad (drgawad@gmail.com): Nephrology Specialist at Kidney & Urology Center - Alexandria - Egypt. website: www.nephrotube.blogspot.com

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Renal Physiology (IV) - Osmoregulation(Urine Dilution & Concentration)

  1. 1. 1RENAL PHYSIOLOGY (IV) m OSMOREGULATION (URINE DILUTION & CONCETRATION) Mohammed Abdel Gawad
  2. 2. OBJECTIVES2  Use of Units in Physiology  Plasma Osmolality Changes  Plasma Osmolality Correction  Counter-Current Multiplier & Exchange Mechanism
  3. 3. OBJECTIVES3  Use of Units in Physiology  Plasma Osmolality Changes  Plasma Osmolality Correction  Counter-Current Multiplier & Exchange Mechanism
  4. 4. Mole & Millimole4
  5. 5. 5 So Mole (& millimole) is a number
  6. 6. Molecular weight6  MW of molecule = weigh (grams) of 1 mole of the molecule For example,  MW of Mg is 24 Therefore, 1 mole of Mg atoms weighs 24 grams.
  7. 7. Use of units: Mole & Molecular weight7
  8. 8. Plasma Solute Concentration (mmol/L & mg/dl)8 Number Weight
  9. 9. 9
  10. 10. Osmolality10  is the number of particles (mmol) contained in one liter of water, so measured in mmol/L.  i.e. it is the concentration by number
  11. 11. Osmolality vs Osmolarity11 Osmola Lity- It is the number of osmoles or moles per kg of solvent Osmola Rity-It is the number of osmoles per liter of solution- Osmole = the amount of a substance that dissociates in solutionto form one mole of osmotically active particles.- For example, a solution of 1 mol/L NaCl corresponds to anosmolarity of 2 osmol/L
  12. 12. Osmolality vs Specific Gravity12  Specific gravity is the mass of one milliliter of solution in grams. This gives an indication of both the number and weight of the particles in the urine.  Most of the time, this provides an accurate estimate of urine concentration; however, if the urine contains particularly heavy particles such as glucose or x-ray dye, the specific gravity will overestimate urine concentration
  13. 13. Osmolality, Calculation13  normally ranges between 285 and 295 mmol/L
  14. 14. Osmolality, Osmolar Gap14
  15. 15. Equivalents15  How to express non electrolytes in equivalent
  16. 16. Equivalents: Electroneutral Body Fluids16
  17. 17. OBJECTIVES17  Use of Units in Physiology  Plasma Osmolality Changes  Plasma Osmolality Correction  Counter-Current Multiplier & Exchange Mechanism
  18. 18. Normal Plasma Osmolality18
  19. 19. Effect of plasma osmolality on cell size19
  20. 20. OBJECTIVES20  Use of Units in Physiology  Plasma Osmolality Changes  Plasma Osmolality Correction  Counter-Current Multiplier & Exchange Mechanism
  21. 21. Osmolality Monitoring - General Concept21  A change in plasma osmolality of only 1% is detectable by the hypothalamus.
  22. 22. How plasma osmolality changes? General Concept22
  23. 23. How body adjust plasma osmolality changes? - General Concept23
  24. 24. How body adjust plasma osmolality changes? - General Concept24
  25. 25. How body adjust plasma hyposmolality (1)? – Suppress Thirst25
  26. 26. How body adjust plasma hyposmolality (2)? – Suppress of ADH26
  27. 27. How body adjust plasma hyperosmolality (1)? – Stimulate Thirst27 Usually the plasma osmolality must increase 5% to stimulate thirst. Thirst (causing the ingestion of water) is the most effective defense against increases in osmolality. This defense is so effective that, with ready access to water, alert people cannot develop significant increases in osmolality
  28. 28. How body adjust plasma hyperosmolality (2)? – Release of ADH28
  29. 29. How body adjust plasma hyperosmolality (2)? – Release of ADH29 3 Steps
  30. 30. Step 1: ADH – Stimuli30  The release of ADH in the setting of volume depletion and the inappropriate release of ADH are two important factors which can initiate the development of hyponatremia.
  31. 31. Step 2: ADH – Formation, Storage & Release31
  32. 32. Step 3: ADH – Action Distal Tubules32
  33. 33. Mechanism of action of ADH(Facultative water reabsorption)(Formation of Water Pores)33
  34. 34. Step 3: ADH – Action Concentrated Medullary Interstitium34
  35. 35. TO MEMORISE35 ADH ADds Hydration to the body by causing the formation of a concentrated urine.
  36. 36. OBJECTIVES36  Use of Units in Physiology  Plasma Osmolality Changes  Plasma Osmolality Correction  Counter-Current Multiplier & Exchange Mechanism
  37. 37. Loop of Henle (Countercurrent Multiplier) &Vasa Recta (Countercurrent Exchange Mechanism)37 Interaction between the flow of filtrate through the loop of Henle (countercurrent multiplier) and the flow of blood through the vasa recta blood vessels (countercurrent exchanger)
  38. 38. RENAL CIRCULATION38
  39. 39. Sodium Tubular Handling39 65% 8-10% 25%
  40. 40. Water Tubular Handling40 65% by osmosis 15% (obligatory Under effect of reabsorption) ADH (Facultative reabsorption) 15-20% by osmosis (obligatory reabsorption)
  41. 41. Loop of Henle: Countercurrent Multiplication41
  42. 42. Loop of Henle: Countercurrent Multiplication42  See the video on our facebook group NephroTube
  43. 43. Vasa Recta: Countercurrent Exchange43
  44. 44. Vasa Recta: Countercurrent Exchange44  See the video on our facebook group NephroTube
  45. 45. Effect of ADH (formation of diluted & concentrated urine)45
  46. 46. Tonicity46 Isotonic Solution Cells normal shape, no loss or gain of water. Hypertonic Solution Cells lose water and shrink. Hypotonic Solution Cells swell rapidly as water rushes into them.
  47. 47. Effect of ADH (formation of diluted & concentrated urine)47  See the video on our facebook group NephroTube
  48. 48. 48 Follow On www.nephrotube.blogspot.com & Facebook Group NephroTube
  49. 49. 49 Gawad

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