As a subject matter expert in respiratory physiology, I can explain the process of oxygen transfer from the lungs to the bloodstream. The process is known as oxygenation or more specifically, gas exchange. This occurs in the alveoli of the lungs where oxygen from the inhaled air diffuses across the thin walls of the alveoli and the surrounding capillaries into the blood. Here's the step-by-step process:

1. Inhalation: Air rich in oxygen is drawn into the lungs.
2. Diffusion: Oxygen molecules move from the alveoli, where the concentration of oxygen is higher, into the capillaries, where the concentration is lower.
3. Binding to Hemoglobin: Once in the bloodstream, oxygen binds to hemoglobin molecules within red blood cells.
4. Circulation: The oxygen-rich blood is then pumped by the heart and circulated throughout the body to be used by cells for various metabolic processes.

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Oxygen and carbon dioxide move from where there is a large concentration to where there is a lower concentration. This movement is called diffusion. Oxygen diffuses from the alveoli, into the blood in the capillaries. Similarly, carbon dioxide from the blood moves out of the capillaries into the alveoli.read more >>