Renal Physiology Pt 3/4 (Acid-Base Balance)

Question 1

General info:

1. Normal pH of plasma?
2. Define pH? Why not measured by HCO3-?
3. Henderson-Hasselbach eqn for calculating pH?

Question 2

A change in the [H+] by a factor of 2 is a change in the pH by ( )?

Question 3

A change in the [H+] by a factor of 10 is a change in the pH by ( )?

Question 4

What is the relationship between H+ & K+ (eg. in acidosis)?

Answer 4

Note: Dr Nathasha “Acidosis per se doesn’t lead to hyperK. But they can frequently be associated with each other due to the mechanisms leading to them in each case (ex-renal failure) and Compensatory mechanisms.
All these electrolytes are regulated by many pathways together so in a healthy person with normal kidneys acidosis per se doesnt give rise to hyperK “

Question 5

How is pH regulated in the body? (Hint: B in cells, R&R in blood)

Question 6

Summarise the regulation of Respi+Renal regulation of pH in blood in a chemical equation.

Question 7

What disorders happen when pH regulation goes wrong?

Question 8

What chemical changes happen in respiratory acidosis and alkalosis?

What are some etiologies of each?

Question 9

What chemical changes happen in metabolic acidosis and alkalosis?

What are some etiologies of each?

Question 10

What are the 3 ‘fates’ of respi/metab acidosis/ alkalosis?

Answer 10

1. w respi/ renal compensation
2. uncompensated
3. simultaneous metab/ respi acidosis/ alkalosis

Question 11

Is renal acidosis/alkalosis = metabolic acidosis/alkalosis, and why?

Question 12

Name the last 2 rules of A-B disorders to assess for compensation (by other systems).

(Hint: Rule 5 for metabolic acidosis; Rule 6 for metabolic alkalosis).

Question 13

Name and explain how compensatory mechanisms for A-B disorders (attempt to) help body achieve homeostasis again?
(Hint: Use the chemical eqn connecting respi&metab CO2 and HCO3- - + think in terms of ‘movement of eqn to the left/right’)

Question 14

How long does respi and renal compensatory mechanism take to kick in respectively?

Question 15

Explain in depth the renal compensation for metabolic acidosis.
+
-> H+ secreted buffered by what in renal tubule filtrate?
-> What membrane protein transports HCO3- back into the blood to buffer the excess H+ ions?

Question 16

Explain the anion gap.
(i) Definition and calculation
(ii) What 1 A-B disturbance are the anion gap used to measure only?

Question 17

Explain what a:
(i) Normal anion gap and a
(ii) High anion gap
means in metabolic acidosis.

Answer 17

(note: always draw your diagram to not get confused!)

(actl, now that I think abt it, anion gap is basically a measure of unmeasured anions in blood - THUS anion gap’s role = help physician try to characterise the aetiology of metabolic acidosis eg. whether ketoacids, lactic acids cause the acidosis and not increase in H+ or severe decrease in HCO3-)