Pathophysiology

Pathophysiology Study Guide

©2018 of 131 Acidosis Acidosis is characterized by the increase in acidity in the blood due to excessive acid and a loss of bicarbonate in the blood; it is termed metabolic acidosis. It is caused by the rise in carbon dioxide in the blood, basically resulting from poor lung function and slow breathing, termed respiratory acidosis. Major causes of metabolic acidosis are diabetic ketoacidosis; drugs like alcohol, aspirin, acetazolamide, and iron; lactic acid build up due to shock; lack of bases, like bicarbonate, due to diarrhea, colostomy, and ileostomy; chronic kidney disease; poisoning from carbon monoxide, cyanide, ethylene glycol, and methanol; and malfunctioning of the kidney causing renal tubular acidosis. The causes of respiratory acidosis are lung disorders like emphysema, chronic bronchitis, pneumonia, severe asthma, and pulmonary edema. Sleep disordered breathing, nerves or muscular disorders that impair breathing (Guillain-Barre syndrome), amyotrophic lateral sclerosis, and overdose of certain drugs, like opioid or sedatives, is also a cause of the disease. Symptoms of metabolic acidosis are vomiting, nausea, deep breaths, fatigue, weakness, drowsiness, state of confusion followed by hypotension, shock, coma, and death. The symptoms of respiratory acidosis are headache, feeling drowsy, stupor, and coma. Alkalosis Alkalosis is the imbalance in the acid base composition in the blood, which can be caused due to metabolic or respiratory mechanisms. When the bicarbonate rises excessively, or acid is lost from blood, it is known as metabolic alkalosis, while respiratory alkalosis is caused due to a low level of carbon dioxide in the blood. The causes of metabolic alkalosis include loss of acid due to vomiting and drainage from the stomach, overactive adrenal gland, and the use of diuretics. Causes of respiratory alkalosis include anxiety, pain, overdose of aspirin, fever, and a fall in oxygen level in the blood. Signs and symptoms of alkalosis include irritation, muscle twitching, cramps in muscles, and prolonged contraction. Buffers The proper balance between acids and bases, termed as body pH, is maintained through acid-based homeostatic. When this balance gets impaired, then denaturation and digestion of proteins occur, which influences the enzymes causing them to lose their ability to function normally, which has the potential to cause death. One such mechanism that helps to maintain the balance between acids and bases in the body are buffer solutions. Buffer solutions are an aqueous solution that are comprised of the blend of either a weak acid and conjugate base, or a week base and conjugate acid. One of the vital instances of buffer solution is blood. Other instances of buffer solutions are bicarbonate and ammonia that are termed as extracellular buffers; proteins and phosphate are intracellular buffers. For instance, carbon dioxide can be transferred to hydrogen ions, and bicarbonate through carbonic acid, as given in the equation: 2 + 2 ↔ 2 3 ↔ + + 3− Further, the acid-base imbalances that overcome these buffer solutions can be corrected through altering the ventilation rate in the short term. Through this, the level of carbon dioxide gets altered to pH as per the reaction shown above. The renal system excretes the excess amount of acids or base and controls the pH level in the blood. In acidosis, bicarbonate is reabsorbed from the tubular fluid Achieve Page 80