Flashcards in Acid Base Deck (28)
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1
What is the difference between acidemia/alkalemia and acidosis/alkalosis?
-emia: simply represents a change in pH, NOT the cause
-osis: describes the process that leads to a change in pH
ie: metabolic or repiratory
2
Simplified Henderson-Hasselblach (Kaiser-Bleich) equation for relating H+, HCO3-, and PCO2:
[H+] = 24 (PCO2)
----------------
[HCO3-]
3
~ pH if [H+] = 40
7.4
4
~pH if [H+] = 50
7.3
5
~pH if [H+] = 60
7.2
6
~pH if [H+] = 70
7.1
7
Two primary mechanisms of managing acid load:
1. buffering (HCO3-)
2. Renal excretion
8
Four ways to increase activity of Na+/H+ antiporter (which gets excess H+ into PROXIMAL tubule lumen):
1. incr. Angiotensin II
2. incr. SNS drive
3. incr. CO2
4. DECR. pH
9
What players are involve in transporting H+ into prox tubule lumen via NH4+?
Glutaminase increases with high H+ (increase activity of carbonic anhydrase)
Makes NH4+ from glutamine
NH4+ gets antiported against Na+
10
Why is ammoniagenesis (creation of NH4+) favored in cells?
pK is 9 vs cell pK of 7
11
Two ways urinary H+ is buffered and excreted?
1. HPO4- : 1/3
-limited by amount of phosphorus filtered
2. NH4+ : 2/3
12
Where are Beta-intercalated cells found?
What do they do?
Collecting duct next to alpha-intercalated cells
They secrete bicarb via Cl- antiporter (good for alkalosis)
13
Time for kidney to compensate for respiratory acid/base derrangements?
days
14
Time for lungs to compensate for metabolic acid/base derrangments?
minutes
15
Primary rise in pCO2 due to lack of ventilation:
respiratory acidosis
16
Drug/disease causes of respiratory acidosis:
morphine
succinylcholine
GHB
heroin
PE
pulm obstruction
COPD
17
Increase in fixed acid production:
metabolic acidosis
-not an issue of CO2
18
Two ways to cause metabolic acidosis:
Increased H+ (lactate, ketones, salycilates, methanol)
Decreased bicarb (diarrhea, laxative abuse)
19
Pulmonary compensation for metabolic acidosis:
Kussmaul breathing (DEEP, SLOW)
20
Renal response to acidosis:
Resorb all bicarb
Excrete fixed acid load (NH4, H+ transporters in collecting duct)
21
Too much breathing decreasing CO2:
Respiratory alkalosis
22
Renal response to respiratory alkalosis?
BICARB secretion and consumption via:
B-intercalated cells
inhibition of Na+/H+ transporter
Liver converts NH4 to urea which consumes bicarb
23
Net loss of H+ from extracellular space:
metabolic alkalosis
24
Causes of metabolic alkalosis?
vomiting
NG tube
25
Liver/pancreas role in metabolic alkalosis?
Secrete bicarb in anticipation of buffering H+ from stomach that never gets to the duodenum
26
Where does ammoniagenesis occur?
Proximal tubule
27
What do you get from ammoniagenesis in the proximal tubule that helps with acid base management?
2 bicarbs for every glutamine molecule
28
