Acid Base Flashcards

1
Q

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

A

-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
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2
Q

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

A

[H+] = 24 (PCO2)
—————-
[HCO3-]

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3
Q

~ pH if [H+] = 40

A

7.4

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4
Q

~pH if [H+] = 50

A

7.3

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5
Q

~pH if [H+] = 60

A

7.2

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6
Q

~pH if [H+] = 70

A

7.1

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7
Q

Two primary mechanisms of managing acid load:

A
  1. buffering (HCO3-)

2. Renal excretion

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8
Q

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

A
  1. incr. Angiotensin II
  2. incr. SNS drive
  3. incr. CO2
  4. DECR. pH
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9
Q

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

A

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

Makes NH4+ from glutamine

NH4+ gets antiported against Na+

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10
Q

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

A

pK is 9 vs cell pK of 7

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11
Q

Two ways urinary H+ is buffered and excreted?

A
  1. HPO4- : 1/3
    - limited by amount of phosphorus filtered
  2. NH4+ : 2/3
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12
Q

Where are Beta-intercalated cells found?

What do they do?

A

Collecting duct next to alpha-intercalated cells

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

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13
Q

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

A

days

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14
Q

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

A

minutes

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15
Q

Primary rise in pCO2 due to lack of ventilation:

A

respiratory acidosis

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16
Q

Drug/disease causes of respiratory acidosis:

A

morphine

succinylcholine

GHB

heroin

PE

pulm obstruction

COPD

17
Q

Increase in fixed acid production:

A

metabolic acidosis

-not an issue of CO2

18
Q

Two ways to cause metabolic acidosis:

A

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

Decreased bicarb (diarrhea, laxative abuse)

19
Q

Pulmonary compensation for metabolic acidosis:

A

Kussmaul breathing (DEEP, SLOW)

20
Q

Renal response to acidosis:

A

Resorb all bicarb

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

21
Q

Too much breathing decreasing CO2:

A

Respiratory alkalosis

22
Q

Renal response to respiratory alkalosis?

A

BICARB secretion and consumption via:

B-intercalated cells

inhibition of Na+/H+ transporter

Liver converts NH4 to urea which consumes bicarb

23
Q

Net loss of H+ from extracellular space:

A

metabolic alkalosis

24
Q

Causes of metabolic alkalosis?

A

vomiting

NG tube

25
Q

Liver/pancreas role in metabolic alkalosis?

A

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

26
Q

Where does ammoniagenesis occur?

A

Proximal tubule

27
Q

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

A

2 bicarbs for every glutamine molecule

28
Q

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

A

a-intercalated cell

collecting tubule