Pulmonary Capillaries · Histology

Which of the following is true regarding the 'blood-air barrier' thickness?

  1. It is approximately 5–10 millimeters thick
  2. It averages 0.1 to 1.5 micrometers in thickness
  3. It is considerably thicker than the wall of the aorta
  4. It is composed of ten distinct cell layers
Show answer and explanation

Correct answer: It averages 0.1 to 1.5 micrometers in thickness

To allow for rapid passive diffusion of gases, the barrier must be as thin as possible. In many areas, it measures only a fraction of a micrometer, representing one of the thinnest biological membranes in the body.

Difficulty: Medium Question 13 of 20

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