A research scientist attempts to understand the influence of carbon dioxide content in blood on its oxygen binding. The scientist adds carbon dioxide to dog blood and measures the uptake of oxygen in the blood versus oxygen pressure in the peripheral tissue. He notes in one dog that with the addition of carbon dioxide with a pressure of 90 mmHg, the oxygen pressure in the peripheral tissue rose from 26 to 33 mmHg. How can this phenomenon be explained?
AHigh partial pressure of CO2 in tissues decreases peripheral blood volume
BBinding of O2 to hemoglobin in lungs drives release of CO2 from hemoglobin
CHigh partial pressure of CO2 in tissues causes alkalemia, which is necessary for O2 unloading
DHigh partial pressure of CO2 in tissues facilitates O2 unloading in peripheral tissues
EThe sum of the partial pressures of CO2 and O2 cannot exceed a known threshold in blood
A 60-year-old woman with a history of emphysema has been referred by her pulmonologist for follow-up pulmonary function testing. During the test, the patient reaches a point where her airway pressure is equal to the atmospheric pressure. Which of the following is most likely to be found during this respiratory state?
APulmonary vascular resistance is at a maximum
BTransmural pressure of the lung-chest wall system is at a maximum
CTransmural pressure of the chest wall is at a minimum
DPulmonary vascular resistance is at a minimum
ETransmural pressure of the lung-chest wall system is at a minimum
A 62-year-old woman with hypertension and type 2 diabetes mellitus comes to the physician because of increasing shortness of breath and a dry cough over the past 6 months. She has smoked 1 pack of cigarettes daily for the past 40 years. Chest auscultation shows scattered expiratory wheezes in both lung fields. Spirometry shows an FEV1:FVC ratio of 65% and an FEV1 of 70% of predicted. Her diffusing capacity for carbon monoxide (DLCO) is 42% of predicted. Which of the following is the most likely diagnosis?
APulmonary fibrosis
BBronchial asthma
CEmphysema
DBronchiectasis
EChronic bronchitis
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