PH. AND BUFFER.pptx

Ph

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

10. Thank You