Lecture 40: Acid Base I

Question 1

What is an acid?

What is a base?

What is a buffer?

Answer 1

Acid: A chemical that release H+ ions in solution, has a pH below 7 and more H+ ions than OH- ions

Base: A chemical that takes up/accepts H+ ions in solution, has a pH above 7 and has more OH- ions that H+

Buffer: A buffer is a substance that acts to minimise the changes in pH when an acid or base is added to a solution

Question 2

What is pH?

What is acidosis?

What is alkalosis?

Answer 2

pH: is a measure of how acidic or basic a solution is

acidosis: pH is less than 7.35
= respiratory disfunction, depression of CNS which leads to drowsiness and coma

alkalosis: pH is more than 7.45
= headache, muscle twitches, drowsy and tetany convulsions

Question 3

What is the pH of the ICF?
What is the pH of the ECF?

Why is pH tightly regulated?

Answer 3

ICF = 7.1 - 7.2
ECF = 7.35 - 7.45
Regulation of pH is crucial because important cellular processes depend on the maintenance of optimal pH:
- activity of enzymes and hormones
- function of ion transporters
- normal cell function, growth and division

Question 4

What are the sources of H+ gains?

Answer 4

• Generation of H+ from CO2
• Production of non-volatile acids from the metabolism of proteins and other organic molecules
• Gains of H+ due to loss of HCO3- in diarrhoea, urine and the non-gastric GI fluids

Question 5

What are the sources of H+ losses?

Answer 5

• Utilisation of H+ in the metabolism of the various organic anions
• loss of H+ in vomit and urine
• Hyperventilation

Question 6

What happens when someone is hyperventilating ?

What happens when someone is hypoventilating?

Answer 6

Hyperventilating: Too much CO2 is lost = alkalotic
- breath CO2 out = too much ventilation
Hypoventilating: CO2 accumulates = acidosis
- don’t breath enough = too little ventilation

Question 7

What are the main buffers for acid produced in metabolism ?

How do they achieve this ?

Answer 7

• Bicarbonate
• Proteins
• Phosphate