Final answer:
Hemoglobin within the lungs has a high affinity for oxygen due to the high partial pressures of oxygen there, enabling effective oxygen loading onto red blood cells. This high affinity allows for the efficient transport of oxygen throughout the body, which is then released into tissues where oxygen pressure is lower.
Step-by-step explanation:
It is true that inside of the lungs, hemoglobin has a high affinity for oxygen gas. The oxygen-hemoglobin dissociation curve exhibits an S-shaped pattern, indicating that at high oxygen pressures, such as those found in the lungs, hemoglobin's affinity for oxygen is indeed high. This allows hemoglobin in the red blood cells (RBCs) to be fully loaded with oxygen.
More specifically, within the alveolar capillaries, a high partial pressure of oxygen exists (approximately 100 mm Hg in the alveoli compared to 40 mm Hg in the capillaries). This pressure gradient causes oxygen to diffuse into the capillaries and bind to hemoglobin much more readily than carbon dioxide. This property is vital for the efficient transport of oxygen from the lungs to the body's tissues, where the lower pressure allows hemoglobin to release oxygen.
Additionally, the Haldane effect describes how oxygenated hemoglobin has a reduced affinity for carbon dioxide, which facilitates the unloading of carbon dioxide in the lungs and the uptake of oxygen.