REB 28. Renal Control of Acid-Base Balance

Question 1

What is the measurement of pH? (the formula)

Answer 1

pH = -log[H+]
OR
pH = log (1/[H+])

Question 2

What is the cell pH required for normal cell function?

Answer 2

pH = 7

Question 3

If there are slight deviations in the pH what may happen in the body?

Answer 3

It can change…

• protein structure
• enzyme activity
• nerve excitability

Question 4

What is the average blood pH? What is the range of the pH for blood?

Answer 4

blood pH = 7.4
range = 7.35 to 7.45
(pH = 7.35 // venous blood)
(pH = 7.45 // arterial blood)

Question 5

When you maintain plasma pH, what else do you maintain?

Answer 5

cell fluid pH

- plasma pH = cell fluid pH

Question 6

What is the fatal pH range?

Answer 6

<6.8 and >8.0

Question 7

What are the mechanisms by which “acid” accumulates in the body? (acid is associated with pH and so, change is acid may result in change to pH)

Answer 7

[1] METABOLISM IN ALL TISSUES CONTINUOUSLY PRODUCES CO2

• CO2 + H20 = H2CO3
• in water, H2CO3 dissociates to HCO3- and H+
• increase in CO2 = increase in acidity (H+) of ECF/plasma
• but, this is “potential” acid – the pCO2 does not rise in the blood because the lungs “blow off” the CO2 as rapidly as it is produced

[2] BREAKDOWN OF FOOD PRODUCES NON-VOLATILE ACIDS
- breakdown of protein/meat releases sulphur + phosphorous which sulphuric and phosphoric acids (non-carbonic)

[3] METABOLIC INTERMEDIATES

• e.g. lactic acid during heavy exercise
• creates non volatile acids

The lungs cannot deal with non-volatile acids by blowing off CO2

Question 8

Can the lungs deal with non-volatile acids?

Answer 8

No, the lungs cannot deal with non-volatile acids by blowing off CO2

Question 9

How many buffering systems for acid does the body have?

Answer 9

4:
[1] Bicarbonate Buffer System
[2] Phosphate Buffer System
[3] Haemoglobin System
[4] Plasma and Cell Proteins

Question 10

What are the 4 different buffering systems in the body?

Answer 10

[1] Bicarbonate Buffer System
[2] Phosphate Buffer System
[3] Haemoglobin System
[4] Plasma and Cell Proteins

Question 11

Which buffering system is the major system used for buffering pH changes brought about by causes other than CO2-generated H2CO3?

Answer 11

Bicarbonate Buffer System

Question 12

How is blood pH maintained? [2]

Answer 12

[1] by LUNGS

• which blow off CO2
• respiratory regulation of pH by controlling CO2

[2] by RENAL SYSTEM (KIDNEYS)
- control of HCO3- (to buffer the acid)

Question 13

What dysfunctions can lead to acid-base imbalances?

Answer 13

renal + respiratory dysfunction can lead to acid-base imbalances

Question 14

What ratio does blood pH depend upon?

Answer 14

ratio of [HCO3-] to [H2CO3]