Acid Base

Question 1

What is the difference between acidemia/alkalemia and acidosis/alkalosis?

Answer 1

-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

Question 2

Simplified Henderson-Hasselblach (Kaiser-Bleich) equation for relating H+, HCO3-, and PCO2:

Answer 2

[H+] = 24 (PCO2)
—————-
[HCO3-]

Question 3

~ pH if [H+] = 40

Answer 3

7.4

Question 4

~pH if [H+] = 50

Answer 4

7.3

Question 5

~pH if [H+] = 60

Answer 5

7.2

Question 6

~pH if [H+] = 70

Answer 6

7.1

Question 7

Two primary mechanisms of managing acid load:

Answer 7

1. buffering (HCO3-)

2. Renal excretion

Question 8

Four ways to increase activity of Na+/H+ antiporter (which gets excess H+ into PROXIMAL tubule lumen):

Answer 8

1. incr. Angiotensin II
2. incr. SNS drive
3. incr. CO2
4. DECR. pH

Question 9

What players are involve in transporting H+ into prox tubule lumen via NH4+?

Answer 9

Glutaminase increases with high H+ (increase activity of carbonic anhydrase)

Makes NH4+ from glutamine

NH4+ gets antiported against Na+

Question 10

Why is ammoniagenesis (creation of NH4+) favored in cells?

Answer 10

pK is 9 vs cell pK of 7

Question 11

Two ways urinary H+ is buffered and excreted?

Answer 11

1. HPO4- : 1/3
   - limited by amount of phosphorus filtered
2. NH4+ : 2/3

Question 12

Where are Beta-intercalated cells found?

What do they do?

Answer 12

Collecting duct next to alpha-intercalated cells

They secrete bicarb via Cl- antiporter (good for alkalosis)

Question 13

Time for kidney to compensate for respiratory acid/base derrangements?

Answer 13

days

Question 14

Time for lungs to compensate for metabolic acid/base derrangments?

Answer 14

minutes

Question 15

Primary rise in pCO2 due to lack of ventilation:

Answer 15

respiratory acidosis

Question 16

Drug/disease causes of respiratory acidosis:

Answer 16

morphine

succinylcholine

GHB

heroin

PE

pulm obstruction

COPD

Question 17

Increase in fixed acid production:

Answer 17

metabolic acidosis

-not an issue of CO2

Question 18

Two ways to cause metabolic acidosis:

Answer 18

Increased H+ (lactate, ketones, salycilates, methanol)

Decreased bicarb (diarrhea, laxative abuse)

Question 19

Pulmonary compensation for metabolic acidosis:

Answer 19

Kussmaul breathing (DEEP, SLOW)

Question 20

Renal response to acidosis:

Answer 20

Resorb all bicarb

Excrete fixed acid load (NH4, H+ transporters in collecting duct)

Question 21

Too much breathing decreasing CO2:

Answer 21

Respiratory alkalosis

Question 22

Renal response to respiratory alkalosis?

Answer 22

BICARB secretion and consumption via:

B-intercalated cells

inhibition of Na+/H+ transporter

Liver converts NH4 to urea which consumes bicarb

Question 23

Net loss of H+ from extracellular space:

Answer 23

metabolic alkalosis

Question 24

Causes of metabolic alkalosis?

Answer 24

vomiting

NG tube

Question 25

Liver/pancreas role in metabolic alkalosis?

Answer 25

Secrete bicarb in anticipation of buffering H+ from stomach that never gets to the duodenum

Question 26

Where does ammoniagenesis occur?

Answer 26

Proximal tubule

Question 27

What do you get from ammoniagenesis in the proximal tubule that helps with acid base management?

Answer 27

2 bicarbs for every glutamine molecule

Question 28

Where is the HCO3/Cl antiporter to get HCO3 back into the blood?

Answer 28

a-intercalated cell

collecting tubule