How is most of the oxygen transported from the lungs to the cells in a normoxic patient?

Oxygen is primarily transported from the lungs to the cells via binding to hemoglobin in red blood cells. In a normoxic patient, the majority of oxygen molecules diffuse into the bloodstream and attach to hemoglobin, forming oxyhemoglobin. This binding allows for efficient transport because hemoglobin has a high affinity for oxygen, facilitating its transportation even at relatively low concentrations in plasma.

While some oxygen is indeed dissolved in plasma, this dissolved oxygen accounts for a very small fraction of the total oxygen transported—less than 2%—making hemoglobin's role vital to meet the body's oxygen demands. This mechanism not only maximizes the amount of oxygen carried in the bloodstream but also helps maintain adequate oxygen levels throughout the body, especially during times of increased metabolic activity.