The gauge pressure inside an alveolus with a 200 µm radius is 25 mmhg, while the blood pressure outside is only 10 mmhg. assuming the alveolus acts like a spherical bubble, what is the surface tension of the fluid and membrane around the outside of the alveolus? how does this compare to the surface tension of water?

The surface tension is 0.0318 N/m and is sufficiently less than the surface tension of the water.

Solution:

As per the question:

Radius of an alveolus, R =

Gauge Pressure inside,

Blood Pressure outside,

Now,

Change in pressure,

Since the alveolus is considered to be a spherical shell

The surface tension can be calculated as:

And we know that the surface tension of water is 72.8 mN/m

Thus the surface tension of the alveolus is much lesser as compared to the surface tension of water.

would be false hope this out