Regulatory Mechanism

ACID BASE ABNORMALITIES ACIDOSIS Increased acid or decreased base in body that leads to pH <7.36

ALKALOSIS Increased base or decreased acid that leads to pH >7.45

RESPIRATORY COMPENSATION BY ACIDOSIS ALKALSOSIS

PRIMARY SECONDARY INCREASED CO2 DECREASED CO2

INCREASED HCO3 INCREASED HCO3

METABOLIC ACIDOSIS ALKALOSIS

DECREASED HCO3 INCREASED HCO3

RESPIRATORY ACIDOSIS Causes Decreased alveolar ventilation – • COPD • Respiratory depressants drugs

RESPIRATORY ALKALOSIS CAUSES Increased alveolar ventilation • Hyperventilation • Anxiety

DECREASED CO2 INCREASED CO2

RESPIRATORY ACIDOSIS

RESPIRATORY ALKALOSIS

Definition

Characterized by primary Characterized by decreased CO2 increase in CO2 (Hypocapnia) leading to (Hypercapnia) leading to increased arterial pH. reduced arterial pH.

Compensated by

1. Renal tubular secretion 1. Renal tubular secretion of H+ of H+ is increased leading is decreased leading to fall in pH. to rise of pH. 2. Decreased HCO3 reabsorption. 2. Increased HCO3 reabsorption.

pH

Less than 7.36.

PCO2(mmHg) HCO3 Causes

> 44 26 Decreased alveolar ventilation due to 1. COPD 2. Respiratory depressant drugs. 3. Breathing 7%CO2.

METABOLIC ACIDOSIS CAUSES • Diabetic ketoacidosis • Lactic acidosis • Severe diarrhea • Salicylate poisoning METABOLIC ALKALOSIS Cause • Loss of acid- vomiting • Intake of HCO3

More than 7.44 < 32 22 Increased alveolar ventilation due to 1. anxiety 2. High altitude. 3. Overdose of salicylates.

METABOLIC ACIDOSIS Definition

METABOLIC ALKALOSIS

Characterized by reduced Characterized by elevated HCO3 leading to decreased HCO3 leading to increased pH. pH.

Compensated Respiratory compensation: by decreased pH stimulates the respiration leading to decreased pCO2. Ph increases to normal level. Renal compensation: excretion of H+ ions.

Decreased H+ ions inhibit respiration, → increased pCO2→ Increased H2CO3↔H+ + HCO3. pHis restored back to normal. Increased HCO3 excretion.

Causes:

1. diabetic ketoacidosis. 2. lactic acidosis. 3. severe diarrhea. 4. salicylate poisoning

pH

7.28

pCO2

40

HCO3

< 20

1. loss of acid : vomiting 2. intake of HCO3.

COMPENSATORY MECHANISMS RESPIRATORY ACIDOSIS • Increased Renal tubular secretion of H • Increased HCO3 reabsorption RESPIRATORY ALKAOSIS • Decreased renal tubular secretion of H • Decreased HCO3 reabsorption

>7.46 40 > 20 .

Metabolic acidosis Respiratory compensation Hyperventilation Renal compensation H secreted in tubular lumen and excreted by various buffers in kidney

METABOLIC ALKALOSIS Respiratory compensation Hypoventilation

Decreased H -----------hypoventilation ---------increased CO2 increased HCO3 + H Renal compensation

Increased HCO3 excretion

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