Gas exchange — Flashcards

Flashcard 111: Methemoglobinemia is associated with _____ O2 saturation on pulse oximetry and _____ PaO2

Answer: decreased (85%)

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Flashcard 112: Is it more efficient to change tidal volume or respiratory rate to change O2 and CO2 levels? _____

Answer: Tidal Volume

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Flashcard 113: Hypoventilation = _____ A-a gradient and respiratory acidosis

Answer: ↔

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Flashcard 114: ↓ DLCO = _____

Answer: emphysema

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Flashcard 115: What is the normal range of Pco2, arterial blood (room air)?

Answer: 35–45 mm Hg

Extra: The average normal arterial PCO₂ is 40 mm Hg.

Flashcard 116: What is the normal range of PO2, arterial blood (room air)?

Answer: From 75 to 105 mm Hg

Flashcard 117: 28 y/o man comes with anxiety, weakness, dyspnea, & headaches. - He was accidentally exposed to nitrites in his research lab. - Physical exam: cyanosis that is not improved by administration of supplemental oxygen via facemask. - Analysis of a sample of arterial blood drawn from this patient prior to any oxygen supplementation is most likely to reveal normal value of what?

Answer: Partial pressure of oxygen (PaO2) In methemoglobinemia, nitrites/oxidants convert iron from the ferrous (Fe2+) to the ferric (Fe3+) state. Methemoglobin (Fe3+) cannot bind oxygen, reducing oxygen-carrying capacity. However, PaO2 represents the amount of oxygen dissolved in the plasma (not bound to hemoglobin), which remains normal as long as lung function and alveolar gas exchange are intact.

Flashcard 118: A researcher is studying the structural changes of hemoglobin during gas exchange. During the transition of hemoglobin from the deoxygenated (T) state to the oxygenated (R) state, the molecule is most likely to release which of the following? a.) Chloride b.) Heme c.) Oxygen d.) Phosphate e.) Protons

Answer: e.) Protons This describes the **Haldane effect**. In the lungs, the binding of oxygen to hemoglobin (transition from T to R state) causes the hemoglobin molecule to release protons (H+). These protons then react with bicarbonate to form CO2, which is exhaled. Conversely, the **Bohr effect** occurs in the tissues, where increased H+ (acidity) stabilizes the T state and promotes the release of oxygen.

Extra: Factors that shift the Oxygen-Dissociation Curve: - **Right Shift (unloading O2 to tissues):** ↑ H+ (↓ pH), ↑ CO2, ↑ 2,3-BPG, ↑ Temperature. - **Left Shift (increased affinity for O2):** ↓ H+ (↑ pH), ↓ CO2, ↓ 2,3-BPG, ↓ Temperature, HbF, Carbon Monoxide.

Flashcard 119: In a healthy patient, can exercise alone make patients hypoxemic?_____

Answer: No

Flashcard 120: The lung diffusing capacity (DL) is the equivalent of _____ of the alveolar-pulmonary capillary barrier

Answer: permeability