Glossary of 12. Acid-Base balance and Blood gases

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What are the 5 major buffer systems?
1. Carbonic acid/Bicarb (plasma and cells)
2. Protein (plasma)
3. Hemoglobin (RBCs)
4. Phosphate (plasma/cells/urine)
5. Ammonia (urine)
What buffer is the major extracellular buffer?
What buffer is the major intracellular?
-What protein is the main protein buffer?
-How does it buffer?
Albumin; via the imidazole group of histidine
Which buffers do/can buffer base?
Bicarbonate and Phosphate
What is the normal Base:acid ratio in the hh eqn?
Which component in the HH eqn reflects renal changes? Which reflects respiratory changes?
Renal = top metabolic HCO3
Resp = lower respirty CO2
In the bicarb buffer system:
-What shifts rxtn to left?
-What shifts rxtn to right?
Left: increase in acid
Right: increase in base
(these are the body RESPONSES)
The term for when other conjugate bases act in concert with the bicarb sytem
What detects changes in pCO2?
-Chemoreceptors in medulla
-Aortic/carotid bodies
How does respiration change in
-Metabolic acidosis?
-Metabolic alkalosis?
Acidosis: increase respirations to blow off CO2
Alkalosis: depress respiratns to increase CO2
What is the relationship between pO2 and pCO2?
As PCO2 increases, pO2 decreases and vice versa
What is the Bohr effect?
Shifting of O2 diss. curve based on acid/base conditions.
How does the Hb curve shift:
-in Acid?
-in Base?
Acid: shift to right
Base: shift to left
What is the Haldane effect?
the effect of pCO2 on the Hb-O2 dissociation curve.
How does the O2 diss curve shift with
-Increased CO2?
-Decreased CO2?
Incr. CO2 = shift to right (acidosis)

Decr. CO2 = shift to left
What happens to Hb's O2 affinity when curve shifts
-To the right?
-To the left?
Right = decreased affinity - lose oxygen more easily
Left = increased affinity - harder to give oxygen to tissue
How does CO2 enhance oxygen release from hemoglobin?
By binding alpha amino groups of N-terminal valines on both Alpha and Beta chains
How does 2,3-DPG enhance O2 release from hemoglobin?
By binding alpha amino groups of N-terminal valines on ONLY Beta chains.
On a Hb molecule:
-Where does O2 bind?
-Where does H+ bind?
-O2 binds Iron group

-H+ binds imidazole group of histidine (similar to acid buffing by albumin)
What is oxidized Hb bound to?
Hydrogen; oxygenated hemoglobin is not denoted as oxidized.
What enzyme keeps hemoglobin in its reduced state?
Methemoglobin reductase, which requires NADH
What is the function of the ISOHYDRIC shift?
To remove excess CO2 from the tissues after Hb delivers O2.
What is the function of the Chloride shift?
To maintain the RBC's electronegativity while buffering.
How does the Isohydric shift work?
1. O2 is delivered
2. CO2 diffuses into RBC
3. CO2 + H2O = H2CO3 = H+ and HCO3-
4. H+ binds naked Hgb
5. HCO3- diffuses out of RBC.
How does the Chloride shift work?
When HCO3 diffuses out of RBC, CL- diffuses in to balance the cell's ionic state.
What pH state will produce
Hyper K+ from Acidosis

Hypo K+ from Alkalosis
Where does bicarb reabsorption occur in the kidney?
Proximal tubule
Where does conjugate acid secretion take place in the kidney?
-Distal tubule
what is the pH limit of acidotic urine?
What 2 processes for H+ excretion occur in the distal tubule?
-Titratable acid - Phosphate
What kidney response to Acid is:
-Immediate short term response
-Slow, long-term response?
Immediate = Phosphate titratable acid.

Slow = Ammonium ion excretion
What is the major indicator of a RESPIRATORY disturbance?
What is the primary indicator of a METABOLIC disturbance?
When is BE more off; in respiratory or metabolic disturbance?
Acidosis = --BE
Alkalosis = ++BE
In what 3 conditions is resp alkalosis seen in?
1. Hyperventilation
2. Salicylate toxicity
3. Cirrhosis
In what 3 conditions is metabolic alkalosis seen in?
1. Vomiting - K depletion
2. Diuretic long-term use
3. Cushing's disease
In what 3 conditions is Resp acidosis seen?
1. Central/peripheral resp failure
2. Emphesema
3. Barbiturate toxicity
In what 3 conditions is Metab acidosis seen?
1. Diabetic coma
2. Renal failure
3. Diarrhea w/ pyloric obstruction
What is the treatment for Respiratory Acidosis?
Increase respirations to blow off CO2
What is treatment for Resp alkalosis?
Breathe into bag to increase co2
What is the treatment for Metabolic Acidosis?
Give bicarb viat lactate/citrate ringers
What is the treatment for Metabolic Alkalosis?
Give salt - NaCl, KCl, or NH4Cl to acidify the kidney and induce loss of bicarb.

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