Buffers

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• Buffers

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The Normal pH Range of Some Body Fluids
Fluid pH
Gastric juice 1.0-3.0
Vaginal secretion 3.8
Urine 5.5-7.0
Saliva 6.5-7.5
Blood 7.35-7.45
Intestinal secretions 7.7
Bile 7.8-8.8
Pancreatic juice 8.0
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Buffer Solutions

• Buffer a solution that is capable of maintaining
  its pH at a fairly constant value even when
  small amounts of acids or bases are added

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Buffer Solutions
Acidic buffer solution consists of a weak acid
and a salt of the acid
Alkaline buffer solution sonsists of a weak base
and a salt of the base
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• pH or pOH of a buffer

Henderson-Hasselbach equations
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• Buffer range is a range of pH values over which a
  particular buffer system will function.
• In general, the ratio of ionic species to
  molecular species for an effective buffer should
  be between 1/10 and 10/1

• Buffer capacity is amount of acid or base which
  reduces or increases the pH of 1 liter buffer
  solution with one pH unit

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Acidosis
Type Condition results from Causes
Respiratory Retention of CO2 Blood pH decreases Hypoventilation Emphysema Congestive heart failure Bronchopneumonia Hyaline membrane disease Drugs that depress brain respiratory center
Metabolic Increase in H Blood pH decreases Diabetes mellitus Kidney failure Ingestion of acidic drugs such as aspirin Loss of HCO3-
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Alkalosis
Type Condition results from Causes
Respiratory Rapid expulsion of CO2 Blood pH increases Hyperventilation High fevers Trauma Hysteria
Metabolic Increase in basic components in the blood Blood pH increases Severe vomiting causing loss of stomach acid Excess ingestion of basic substances Kidney disease
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The carbonic acid/bicarbonate buffer system
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The phosphate buffer system