Which term is defined as the delivery of oxygen to the bloodstream?

• A. Perfusion
• B. Ventilation
• C. Respiration
• D. Oxygenation

Answer: (D)

The key idea is loading oxygen into arterial blood. Oxygenation is the step where oxygen diffuses from the alveolar air into the pulmonary capillaries and binds to hemoglobin (with some dissolved in plasma), increasing the oxygen content of the blood. This is what actually delivers oxygen to the bloodstream for distribution to tissues. Ventilation moves air in and out of the lungs to sustain the oxygen gradient but doesn’t describe the loading of oxygen into blood. Perfusion is about blood flow to the lungs or tissues, which enables gas exchange but isn’t the oxygen content change itself. Respiration can refer to cellular use of oxygen or the broader gas-exchange process, but the term that specifically means delivering oxygen to the bloodstream is oxygenation.