This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET Jan 2020, Subject name: Physiology
[{'content': 'When VA/Q is infinity, it means \nSelect and explain. \nA. Dead space, B. The PO2 of alveolar air is 159 mmHg and PCO2 is 40 mmHg, C. Paial pressure of O2 and CO are equal, D. Atelectasis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: -Ventilation / perfusion ratio - normal = 4l/min/5l/min=0.8 - AV/Q= INFINITY - Means Perfusion (Q) to lungs is zero that is blood supply to that area is hindered making it awasted ventilationin those alveoli. - This may be due to pulmonary embolism causing |ed Physiological DEAD space . DEAD SPACE- Some of the air a person breathes never reaches the gas exchange areas but simply fills respiratory passages where gas exchange does not occur, - called so as its not useful for gas exchange. Physiologial / total dead space = anatomical dead space +alveolar dead space (non perfused/ non functioning Alveoli) In Atelectasisventilation: perfusion ratio (VA/Q) iszero. it is is the most common cause of a physiologic shunt.', 'role': 'assistant'}]