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pH regulation

pH regulation. pH = measure of hydrogen ion concentration pH = -log [H + ] Blood pH = 7.35-7.45 pH imbalances are quickly lethal  body needs to compensate. H + intake: - food - drink - metabolism (carbohydrate, protein, lipid) - breathing H + output - urine. Blood pH.

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pH regulation

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  1. pH regulation

  2. pH = measure of hydrogen ion concentration pH = -log [H+] Blood pH = 7.35-7.45 pH imbalances are quickly lethal  body needs to compensate H+ intake: - food - drink - metabolism (carbohydrate, protein, lipid) - breathing H+ output - urine Blood pH

  3. Figure 19.23

  4. Three lines of defense: - Buffers - Respiration - Kidneys Buffer reactions are nearly instantaneous. However, they are limited to the amount of buffer available in the blood Respiration helps buffer the blood by shifting H+ into HCO3-. However, it can be limiting and take several minutes Kidneys are the only organ which can get rid of H+. However, they can take several hours (time enough to be dead!!- therefore, the presence of the other 2 lines of defense) pH regulation

  5. Three lines of defense: - Buffers - Respiration - Kidneys pH regulation

  6. Buffers: - protein buffer - bicarbonate buffer - phosphate buffer Only free H+ contributes to pH H+ can be shifted from a strong acid to a weaker one. Strong acid  complete dissociation (100) HCl  (100)H+ + (100) Cl- Weak acid  (100) H2CO3  (80) H2CO3 + (20) H+ + (20) HCO3- First line of defense: Buffers

  7. If strong acid intake: H+ + Cl- + ( blood Na+ HCO3-)  Na+ Cl- + H+ + HCO3- Less H+ is circulating into the blood -  smaller shift toward acidosis If strong base intake: Na+OH- + (blood H2 CO3)  H2O + Na+ HCO3- Less OH- is circulating in the blood  smaller shift toward alkalosis pH regulation

  8. Three lines of defense: - Buffers - Respiration - Kidneys Second line of defense: breathing

  9. CO2 + H2O  H2CO3  H+ + HCO3- • CO2 retention: ↑ blood H+ ↓ pH  acidosis • CO2 loss: • ↓ blood H+ pH ↑  alkalosis

  10. Figure 17.22

  11. Figure 19.24

  12. Three lines of defense: - Buffers - Respiration - Kidneys Kidneys are the only organs able to eliminate H+ from the body  slow process Third line of defense: kidneys

  13. H+ can be bound to HCO3- for transport to the bladder and eliminated H+ can be added to NH3 to make ammonia (NH4+) and eliminated H+ can be eliminated directly by exchange with Na+ Urine is usually slightly acid. It’s pH varies with food and drink intakes

  14. Acidosis: Blood pH<7.35 Clinical applications:

  15. Figure 19.28

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