The document explains the concept of pH and acid-base balance, stating that pH is a measure of acidity or alkalinity on a scale from 0 to 14, with normal pH levels ranging from 7.35 to 7.45. It outlines the physiological states of acidosis and alkalosis, defines buffers, and describes the body's three defense mechanisms against pH changes: chemical buffers, the respiratory system, and the kidneys. Additionally, it introduces the Henderson-Hasselbalch equation for calculating pH in relation to acid and base concentrations.

1. PH AND BUFFER
Acid Base Blance
A.L.MUNDIA

2. ACID BASE BALANCE
PH
It is the negative log of the hydrogen ion concentration.
ph= -log[H+]
It is a unit of measure which describe the degree of acidity or alkalinity.
Its measured on a scale of 0-14
7 is neutral, <7 is acidic (high con. H+), >7 is basic (high con. OH-) alkali

3. Acid
Any substance that forms H+ ions in solution (proton donors)
e.g carbonic acid releases H+ ions
Base
Any substance which combines with H+ ions in solution (proton
acceptor)
e.g bicarbonate(HCO3-) accepts H+ ions

4. Normal pH: 7.35 – 7.45
Acidosis
Physiological state resulting from abnormally low plasma pH
Alkalosis
Physiological state resulting from abnormally high plasma pH
Acidemia
Alkalemia

5. BUFFER
Buffer solution is a solution which resist changes in pH when a small
amount of acid or base is added.
Typically a mixture of a weak acid and a salt of its conjugate base or
weak base and a salt of its conjugate acid
Acidic buffer eg CH3COOH + CH3COONa
Basic buffer eg NH4OH + NH4Cl

6. Handerson Hasselbalch equation
HA  H+ + A-
Ka = [H+][A-]/[HA]
pH = pka + log[A+]/[HA]

7. Response to acid base challenge
First line of defence
Two most common chemical buffer groups
-bicarbonate
-non bicarbonate (Hb, protein, phosphate) blood buffer systems act
instantaneously
CO2 +H20  H2CO3 H+ + HCO3  HCO3 +Na  NaHCO3

8. Second line of defence
Respiratory system is considered the second line
It eliminates or retain CO2 hence change in pH are rapid

9. Third line of defence are the kidneys
-movement of bicarbonate
-retention or excretion of acids
- generating additional buffers
May take hours to days