Acid-base balance II: Whole body acid-base balance Flashcards Preview

Renal physiology > Acid-base balance II: Whole body acid-base balance > Flashcards

Flashcards in Acid-base balance II: Whole body acid-base balance Deck (40)
Loading flashcards...
1

what is the first priority if normal acid-base balance is disrupted?

restore pH to 7.4 as soon as possible- compensation

2

what is compensation?

the restoration of pH irrespective of what happens to [HCO3-]p and PCO2

3

what is correction?

restoration of pH and [HCO3-]p and PCO2 to normal

4

what are the 2 classification of disturbances or respiratory origin?

-respiartory acidosis (plasma pH falls)
-Respiratory alkalosis
(plasma pH rises)

5

what are the 2 classification of disturbances or non-respiratory origin?

-Metabolic acidosis
(plasma pH falls)
-Metabolic alkalosis
(plasma pH rises)

6

what is immediate buffering of a pH change?

Immediate dilution of the acid or base in ECF
Blood buffers (i.e. Hb, HCO3-. Acidosis would reduce [HCO3-]p)
Buffers in the ECF (particularly HCO3-)

7

what happens once buffer stores are quickly depleted?

kidney has to rectify stores

8

what can measure pH and Pco2?

blood-gas analyser

9

what is pH proportional to?

[HCO3-]/ [CO2]

10

what diagram can we plott variables on?

Davenport diagram

11

what are the normal values in the davenport diagram?

plasma pH- 7.4
[HCO3-]p - 25mmol/l

12

what is respiratory acidosis?

retention of CO2 by the body e.g. chronic bronchitis

13

how do respiratory disorders generate acidosis?

Co2 retention drives equilibrium to the right

14

what happens during respiratory acidosis?

-Both [H+]p and [HCO3-]p rise
-The increased [H+]p results in acidosis
(remember that pH is only a measure of free [H+])

15

how is uncompensated respiratory acidosis indicated?

pH < 7.35 and PCO2 > 45 mmHg

16

where does respiratory acidosis sit on the davenport diagram?

top left

17

what system compensates for respiratory acidosis?

since respiratory system is the cause- renal system must compensate

18

how does the renal system compensate for respiratory acidosis?

-H+ secretion is stimulated
-All filtered HCO3- is reabsorbed (i.e. no HCO3- excretion)
-H+ continues to be secreted and generates titratable acid (TA) and NH4+
-Acid is excreted and “new” HCO3- is added to the blood

19

why does the [HCO3-] rise in respiratory acidosis?

(a) as a result of the disorder (b) as a result of the renal compensation

20

what does correction of respiratory acidosis require?

requires lowering PCO2 by restoration of normal ventilation

21

what is respiratory alkalosis?

Excessive removal of CO2 by the body e.g. hyperventilation

22

How do these disruptions to ventilation cause respiratory alkalosis?

-Excessive CO2 removal drives equilibrium to the left and so Both [H+]p and [HCO3-]p fall

23

where does respiratory alkalosis sit on the davenport diagram?

bottom right

24

How does the renal system compensate for respiratory alkalosis?

-The H+ secretion is insufficient to reabsorb the filtered HCO3-, even though the load is lower than normal
- HCO3- is excreted and urine is alkaline
-No titratable acid (TA) and NH4+ is formed, so no “new” HCO3- is generated

25

what is the overall compensation and correction by the renal system for respiratory alkalosis?

-Renal compensation further lowers [HCO3-]p
-Correction requires the restoration of normal ventilation

26

what is metabolic acidosis?

Excess H+ from any source other than CO2 e.g. ingestion of acids

27

how is Uncompensated respiratory alkalosis is indicated?

pH > 7.45 and PCO2 < 35 mmHg

28

how does metabolic acidosis effect [HCO3-] p?

[HCO3-]p is depleted as a result of buffering excess H+ or loss of HCO3- from the body

29

how is uncompensated metabolic acidosis indicated?

pH < 7.35, [HCO3-]p is low

30

where is metabolic acidosis found on the davenport diagram?

bottom left