1. Acid-Base Balance – 2nd Lab
Chemical Buffer Systems
Protein
Bicarbonate
Phosphate
Respiratory Adjustments
Renal Adjustments

2. Acid-Base Balance – 2nd Lab pH of Arterial Blood
Normal range
Acidosis
Alkalosis
6.8
7.35
7.45
7.8

3. 1. Chemical Buffer Systems
Overall objective is to _____________________________________
They do not prevent pH changes.
The protein buffer system e.g. Hb + H+  HHB
Intracellular proteins (esp. Hb) and plasma proteins can bind or release H+ as necessary.
If more H+ are added... Many H+ will bind to proteins. Only a portion remain free to affect pH.
If some H+ are removed... proteins will release some of their H+ to replace some of them
Is the #1 buffer system you have. (accomplishes 75% of your buffering)
Most influential in the ICF (inside cells) & (somewhat in plasma)

4. The Bicarbonate Buffer System
Equilibrium exists: H2CO3 HCO H+
If add H+ ...?
Reaction would proceed _____________
# of free H+ would ____________
So pH would ___________
If add HCO3- ...?
Reaction would proceed ____________
# of free H+ would ___________
So pH would ____________

5. H2CO3  HCO3- + H+ If H+ are removed... ?
Reaction would proceed ___________________
# of free H+ _______________
pH would _____
If add H2CO3 ...?
# of free H+ would ___________
pH would ______
The salt NaHCO3 found in body fluids and the HCO3- produced by the pancreas are the sources of the HCO3-
Most influential in ECF outside cells. (somewhat in urine)

6. C) The Phosphate Buffer System
equilibrium H2PO4-  HPO H+
HPO42- = hydrogen phosphate anion
H2PO4- = dihydrogen phosphate anion
originally started as H3PO4 = phosphoric acid
If add more HPO42- …
If add more H2PO4- …
If add more H+ …
most influential in ICF inside cells & urine

7. 2. RESPIRATORY ADJUSTMENTS
Based on your understanding of this equilibrium reaction occurring in the blood:
H2CO3  H+ + HCO3-
CO2 + H2O  H2CO3  H+ + HCO3-
If muscles contraction ↑ then CO2 accumulates so [H+] would _______
And pH ________
And RR should _______
As ventilation increases, [CO2 ] should ________
… so reaction proceeds to the ________
And pH should ____.
At the tissues blood picks up _____
So pH of venous blood is _______.
If decrease ventilation CO2 will ______ & reaction will proceed__________

8. Renal Adjustments
???
Reabsorption
Secretion

9. 3. RENAL ADJUSTMENTS Recall Reabsorption… vs. Secretion…
Due to constant influx of H+ into our blood we usually trend toward _______
So what do the kidneys typically do with H+? ___________
Phosphates (HPO42-) already in the filtrate bind up many incoming free H+
Bicarb (HCO3-) also “ “ “ but not as much
When secrete H+ we also reabsorb HCO3- (a coupled reaction. Fig 26.12)
HCO3- reabsorbed to blood binds up H+ in blood
When reabsorb HCO3- also reabsorb Na+ (a coupled reaction)
Also tend to have a surplus of K+ in our blood so the kidneys should ___________ and Na+ is reabsorbed.
could look at it as “trading” H+ or K+ for the Na+ (and HCO3-) you need to reabsorb.
Which one is secreted is determined by both H+ and K+ concentrations of the blood.
Effect of aldosterone? …may not be what you think

10. Cont’d NH3 is secreted to filtrate to buffer incoming H+
NH4+ (ammonium ion) may also be secreted from blood to get rid of H+
This generates the formation of new HCO3- to be reabsorbed to
the blood.
Urine pH Values:
Normal Urine pH is ___________with extremes of ______ and _____
if <6 … your patient is (or recently was) in _________
If >7… your patient is (or recently was) in _________
Buffers systems in the urine?
Phosphate is # Bicarb # Also NH3 binds with H+ in urine.
Priority goal of the kidneys is to control the pH of the blood rather than the urine.

11. Chemical Buffer Systems
Summary
Chemical Buffer Systems
Protein
Bicarbonate
Phosphate
Respiratory Adjustments
↑↓CO2 and therefore ↑↓ H+
Renal Adjustments
↑↓ H+, HCO3-, NH3, K+