In order for oxygen to reach distant tissues, it must first be inhaled, reach th

Question

In order for oxygen to reach distant tissues, it must first be inhaled, reach the lung alveoli, diffuse through the alveolar membrane, and react with hemoglobin within red blood cells (RBCs) so that it may be carried to tissues via arteries and capillaries. The alveolar epithelium, basement membrane, and lung capillary endothelium are typically 1m thick. Under resting conditions, hemoglobin binding with oxygen reaches a steady state in about 0.33 seconds. Is oxygen diffusion across the alveolus a significant factor in the time required for the hemoglobin to oxygenate as it traverses the capillary? Assume DO2-membrane is 2x10-5 cm2/s.

Explanation / Answer

1µm = 10-4 cm.

Given, DO2-membrane is 2x10-5 cm2/s.

Therefore: Diffusion time = L2 / Dij

= (10-4 cm)2 / 2x10-5 cm2/s

= 0.005 sec.

As the diffusion time of 0.0005 sec, which is much faster than reaction time of 0.33 s. This concludes that diffusion does not delay the oxygenation of hemoglobin.

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