Podcast
Questions and Answers
What is the primary role of buffer systems in the body?
What is the primary role of buffer systems in the body?
- To maintain a stable pH (correct)
- To enhance metabolic functions
- To directly excrete acids
- To increase the production of HCO3-
How do the kidneys compensate for respiratory acidosis?
How do the kidneys compensate for respiratory acidosis?
- Decreasing bicarbonate reabsorption
- Increasing bicarbonate reabsorption (correct)
- Increasing H+ ion secretion
- Decreasing carbonic acid levels
Which statement about chemoreceptors and ventilation is accurate?
Which statement about chemoreceptors and ventilation is accurate?
- They increase ventilation during respiratory acidosis.
- They are not influenced by changes in pH.
- They decrease ventilation during metabolic alkalosis. (correct)
- They modulate oxygen levels in the blood.
What is the expected change in Pco2 for metabolic acidosis?
What is the expected change in Pco2 for metabolic acidosis?
What characterizes the compensation mechanism for respiratory abnormalities by the kidneys?
What characterizes the compensation mechanism for respiratory abnormalities by the kidneys?
Which of the following is NOT a cause of increased anion gap metabolic acidosis?
Which of the following is NOT a cause of increased anion gap metabolic acidosis?
In which of the following scenarios would you expect alkalosis to occur?
In which of the following scenarios would you expect alkalosis to occur?
What happens to ventilation when acidosis is detected by chemoreceptors?
What happens to ventilation when acidosis is detected by chemoreceptors?
Flashcards
Acid-Base Homeostasis
Acid-Base Homeostasis
The body's process to maintain a stable pH in bodily fluids despite metabolic acid production.
Buffers in Acid-Base
Buffers in Acid-Base
Substances that minimize pH changes by absorbing or releasing H+ ions.
Metabolic Acidosis
Metabolic Acidosis
A condition where the body's pH falls below the normal range due to an excess of acids produced inside or taken in from outside.
Respiratory Compensation
Respiratory Compensation
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Metabolic Compensation
Metabolic Compensation
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Anion Gap Metabolic Acidosis
Anion Gap Metabolic Acidosis
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Respiratory Acidosis
Respiratory Acidosis
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Respiratory Alkalosis
Respiratory Alkalosis
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Study Notes
Acid-Base Balance
- Body fluids maintain a narrow pH range despite large acid production
- Buffer systems (intracellular proteins, phosphates, bicarbonate-carbonic acid) neutralize acids
- Kidneys and lungs excrete acids
- Compensation for acid-base imbalances can be respiratory (metabolic imbalances) or metabolic (respiratory imbalances)
- Changes in ventilation are mediated by hydrogen-sensitive chemoreceptors in the carotid body and brain stem
- Acidosis stimulates increased ventilation, and alkalosis decreases it
- Kidneys compensate for respiratory abnormalities by adjusting bicarbonate reabsorption
- Compensation for metabolic abnormalities in the kidneys takes longer, typically 6 hours to several days
Acid-Base Disorders
- Metabolic Acidosis: Increase in H+ concentration; predicted change Pco2 = 1.5 x HCO3- + 8
- Metabolic Alkalosis: Decrease in H+ concentration; predicted change Pco2 = 0.7 x HCO3- + 21
- Respiratory Acidosis: Alveolar ventilation decreases; CO2 retention; predicted change pH = (Pco2 – 40) x 0.008
- Respiratory Alkalosis: Alveolar ventilation increases; CO2 loss; predicted change pH = (40 – Pco2) x 0.017
Metabolic Derangements
- Increased Anion Gap Metabolic Acidosis: Exogenous ingestion (ethylene glycol, salicylate, methanol) or endogenous production (ketoacidosis, lactic acidosis, renal insufficiency)
- Normal Anion Gap Metabolic Acidosis: Acid administration (HCl), bicarbonate loss (diarrhea, fistulas), renal tubular acidosis, carbonic anhydrase inhibition
- Anion Gap (AG): = (Na) – (Cl + HCO3)
- Normal AG < 12 mmol/L
Metabolic Alkalosis
- Chloride-losing (urinary chloride > 20 mEq/L): Mineralocorticoid excess, profound potassium depletion
- Chloride-sparing (urinary chloride < 20 mEq/L): Gastric secretions (emesis), diuretics, excess alkali administration, citrate in blood transfusions, antacids
- Impaired bicarbonate excretion: Decreased glomerular filtration, increased bicarbonate reabsorption
Respiratory Derangements
- Respiratory Acidosis: Decreased alveolar ventilation (narcotics, CNS injury, pulmonary secretions, atelectasis, mucus plug/pneumonia, pleural effusion, pain, abdominal distension, abdominal compartment syndrome)
- Respiratory Alkalosis: Increased alveolar ventilation (pain/anxiety, neurologic disorders, assisted ventilation, salicylates, gram-negative bacteremia, thyrotoxicosis, hypoxemia)
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