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 1mm 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

The time it takes for oxygen to diffuse across the epithelium is on the order of : t ~ L2/DAB.

Length for diffusion is 1 mm = 10-2 cm, so t ~(10-2 cm)2/(2*10-5 cm2/s) =5 second.

comprable with 0.33 sec

Thus: , diffusion is a significant factor for the time required for Hb to oxygenate.

if the thickness would have been 1 micron then

Length for diffusion is 1 micron = 10-4 cm, so t ~(10-4 cm)2/(10-5 cm2/s) = .001 second.

Thus: no, diffusion is not a significant factor for the time required for Hb to oxygenate.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.