Regulation of AcidBase Balance Review Acid contributes hydrogen
Regulation of Acid-Base Balance Review Ø Acid – contributes hydrogen ion l Two types: • Volatile respiratory acid l Dehydrates and excreted in the form of a gas • Nonvolatile metabolic acid l Metabolized and excreted in the form of body fluids
Alterations in Ventilation Regulation of Acid-Base Balance Review Ø Base – accepts or removes hydrogen ion l Buffer- controls the hydrogen ion concentration: • • Absorbing hydrogen ions when an acid is added OR Releasing hydrogen ions when base is added. Ø Three Buffer Systems: l l l Bicarbonate – operates in lungs & kidneys Phosphate – renal tubules Protein – Hgb, plasma proteins, & intracellular protein
Alterations in Ventilation Regulation of Acid-Base Balance Ø Factors to remember: l l Lungs – Eliminate or retain carbon dioxide C 02 Kidneys – excrete or form bicarbonate HC 03 Food – converted by the body – H 20 + CO 2 + energy Lung Kidney C 02 + H 20 = H 2 CO 3 = HCO 3 - + H+
Alterations in Ventilation Normal Acid-Base Balance
Alterations in Ventilation Regulation of Acid-Base Balance Ø Lungs/Respiratory System l Increase or decrease hydrogen ion concentration • Through respiratory rate and depth • Result: C 02 is either retained or eliminated l l Changes can occur within minutes Controlled in the medulla oblongata—respiratory center > = increased; < = decreased l l <p. H causes > respirations = <C 02 + correcting p. H >p. H causes < respirations = >C 02 + correcting p. H
Alterations in Ventilation Regulation of Acid-Base Balance Ø Renal System l l l Reabsorb and conserve bicarbonate Can generate additional bicarbonate and eliminate excess hydrogen ions as compensation for acidosis Three mechanisms: • Secretion of small amounts of free hydrogen into the renal tubule • Combination of hydrogen ions with ammonium to form ammonia • Excretion of weak acids • Urine p. H 4 – 8
Alterations in Ventilation Regulation of Acid-Base Balance > = increased; < = decreased ABG Condition Respiratory process >PCO 2 Respiratory acidosis < PC 02 elimination by the lungs -- hypoventilation <PC 02 >PC 02 elimination by the lungs - hyperventilation Respiratory Alkalosis
Respiratory Alkalosis Respiratory Acidosis
Acid-Base Imbalance Respiratory Acidosis Ø Hypoventilation from primary lung problem l l l Ø Atelectasis Pneumonia Respiratory failure Airway obstruction Chest wall injury Cystic fibrosis Hypoventilation from other factors l l Drug overdose Head injury Paralysis of respiratory muscles Obesity
Acid-Base Imbalance Respiratory Alkalosis Ø Hyperventilation problem l l l from primary lung Asthma Pneumonia Inappropriate ventilator settings Ø Hyperventilation from other factors l l l Anxiety Disorders of the central nervous system Salicylate overdose
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