Respiratory System · NEET PG Preparation Physiology
A patient with severe metabolic acidosis develops compensatory hyperventilation (Kussmaul breathing). Which of the following changes is primarily res…
Practice question from Respiratory System (NEET PG Preparation Physiology), with the correct answer and a step-by-step solution.
medium · MCQ · Q-7DBD49
A patient with severe metabolic acidosis develops compensatory hyperventilation (Kussmaul breathing). Which of the following changes is primarily responsible for mediating this respiratory response?
- A.Direct stimulation of medullary respiratory centers by low arterial pH
- B.Stimulation of peripheral chemoreceptors by decreased arterial PO2
- C.Stimulation of central chemoreceptors due to a decrease in cerebrospinal fluid pHCorrect answer
- D.Activation of pulmonary J-receptors by increased pulmonary capillary pressure
Solution
In metabolic acidosis, arterial H+ ions increase, but H+ ions do not readily cross the blood-brain barrier. However, CO2 diffuses freely across the blood-brain barrier. The hyperventilation induced by metabolic acidosis lowers arterial PCO2 (respiratory alkalosis compensation). The reduced blood PCO2 causes CO2 to diffuse out of the cerebrospinal fluid (CSF), raising CSF pH toward normal, which stimulates the central chemoreceptors located near the ventral surface of the medulla.
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