Back to Basics: Renal Physiology (Normal Acid base balance) - Dr. Gawad
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Back to Basics: Renal Physiology (Normal Acid base balance) - Dr. Gawad
- 1. Back to Basics: Renal Physiology Normal Acid base balance Mohammed Abdel Gawad Nephrology Consultant - Alexandria MD Nephrology - Mansoura University drgawad@gmail.com
- 2. To download the lecture with full animations contact me drgawad@gmail.com For more Nephrology lectures visit www.NephroTube.com
- 4. Henderson–Hasselbalch equation 4 pH = log 1 / H+
- 5. 5 Lactic acid Sulphuric acid Carbonic acid Phosphoric acid Threats to pH • 1. Volatile acids: Carbon dioxide: • 2. Fixed-non volatile acids: ▫ a- Sulphuric acid: an end product of the oxidation of sulphur containing aminoacids, methionine and cysteine. ▫ b- phosphoric acid: formed in the metabolism of phospholipids, nucleic acids, phosphorproteins and phosphoglycerides. • 3. Organic acids: ▫ Lactic acid, acetoacetic acid and B-OH-butyric acid formed during the metabolism of carbohydrates and fats.
- 6. Friday, January 24, 2020 6
- 7. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. • II. The respiratory system, within minutes. • III. The kidneys, within hours. 7
- 8. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. • II. The respiratory system, within minutes. • III. The kidneys, within hours. 8
- 9. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. 9 • A. The bicarbonate buffer system • B- The phosphate buffer system • C- The protein buffer system • D- Bone salts (calcium carbonate and calcium phosphate)
- 10. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. 10 • A. The bicarbonate buffer system • B- The phosphate buffer system • C- The protein buffer system • D- Bone salts (calcium carbonate and calcium phosphate)
- 11. I-ACID-BASE BUFFERS A. The bicarbonate buffer system • consists of a mixture of: • carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3) in the same body fluid. • It is the most important buffer system in the body because: • 1- present in all the body fluids, both ECF & ICF. • 2- concentration of its components (CO2 & HCO3)can be independently regulated 11
- 12. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. 12 • A. The bicarbonate buffer system • B- The phosphate buffer system • C- The protein buffer system • D- Bone salts (calcium carbonate and calcium phosphate)
- 13. I- ACID-BASE BUFFERS B- The phosphate buffer system: • composed of: • more effective in ICF than in ECF: • The total concentration of phosphate is much greater in ICF than ECF. • also effective in buffering the tubular fluid in the kidneys because: • Phosphate becomes greatly concentrated in the tubular fluid due to the reabsorption of water in excess of phosphate. 13
- 14. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. 14 • A. The bicarbonate buffer system • B- The phosphate buffer system • C- The protein buffer system • D- Bone salts (calcium carbonate and calcium phosphate)
- 15. I- ACID-BASE BUFFERS C- The protein buffer system • 1) Proteins of the cells and the plasma:
- 16. I-ACID-BASE BUFFERS C- Protein buffer system 2) Haemoglobin v
- 17. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. 17 • A. The bicarbonate buffer system • B- The phosphate buffer system • C- The protein buffer system • D- Bone salts (calcium carbonate and calcium phosphate) In the short term, bicarbonate is, by far, the most important, though bone buffers play a more significant role in chronic acidosis
- 18. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. • II. The respiratory system, within minutes. • III. The kidneys, within hours. 18
- 19. II- RESPIRATORY REGULATION OF ACID-BASE BALANCE central chemoreceptors in the medulla oblongata peripheral chemoreceptors in aortic and carotid bodies ↑ CO2 → H+ (in blood) → H+ (in CSF)
- 20. Defense against changes in H+ concentration • I. Acid-base buffer systems in body fluids, within seconds. • II. The respiratory system, within minutes. • III. The kidneys, within hours. 20
- 21. 21
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- 23. Defense against changes in H+ concentration 23 1. Reabsorption (reclamation) of the filtered bicarbonate by proximal tubules. 2. Generation of new bicarbonate A- ammonia B- phosphoric, sulphuric acid III. The kidneys
- 24. Defense against changes in H+ concentration 24 1. Reabsorption (reclamation) of the filtered bicarbonate by proximal tubules. 2. Generation of new bicarbonate A- ammonia B- phosphoric, sulphuric acid III. The kidneys
- 25. 1- Reabsorption of the filtered bicarbonate 25
- 26. 1- Reabsorption of the filtered bicarbonate 26
- 27. Defense against changes in H+ concentration 27 1. Reabsorption (reclamation) of the filtered bicarbonate by proximal tubules. 2. Generation of new bicarbonate A- ammonia B- phosphoric, sulphuric acid III. The kidneys
- 28. 2. Generation of new bicarbonate A- ammonia (PCT & DCT) Na Na Cl
- 29. Defense against changes in H+ concentration 29 1. Reabsorption (reclamation) of the filtered bicarbonate by proximal tubules. 2. Generation of new bicarbonate A- ammonia B- phosphoric, sulphuric acid III. The kidneys
- 30. 2. Generation of new bicarbonate B- phosphate (DCT) Na Na Filtered Na2HPO4
- 31. 2. Generation of new bicarbonate B- phosphate (DCT) NaHPO4 + Filtered Na2HPO4 Na Na Na
- 32. Thank You
Editor's Notes
- The PCT reabsorbs 90% of filtered HCO 3 but does not acidify the urine. Within the cell, the HCO 3 generated from carbonic acid dissociation leaves via the basolateral surface in exchange for Cl – or in association with Na + .
- The PCT reabsorbs 90% of filtered HCO 3 but does not acidify the urine. Within the cell, the HCO 3 generated from carbonic acid dissociation leaves via the basolateral surface in exchange for Cl – or in association with Na + .
- Buffering urinary proton: The luminal pH rapidly falls to <4.0, inhibiting A -intercalated cell H + -ATPase. For ongoing net acid excretion, urinary H + is buffered (to keep u-pH >4.0) by: Titratable acids (H + incorporated into phosphoric acid H 3 PO 4 or sulphuric acid H 2 SO 4 ). Ammonium (NH 4 + ). In health, titratable acids and ammonium carry approx 50% of the dietary H + load, but, with metabolic acidosis, more ammonium is needed for acid excretion.
- Buffering urinary proton: The luminal pH rapidly falls to <4.0, inhibiting A -intercalated cell H + -ATPase. For ongoing net acid excretion, urinary H + is buffered (to keep u-pH >4.0) by: Titratable acids (H + incorporated into phosphoric acid H 3 PO 4 or sulphuric acid H 2 SO 4 ). Ammonium (NH 4 + ). In health, titratable acids and ammonium carry approx 50% of the dietary H + load, but, with metabolic acidosis, more ammonium is needed for acid excretion.