Biomedical Engineering 403
Mechanics of Breathing, Part 1

For information on the extra credit assignment, please e-mail me .

Reading for Today:

Chapter 7 in West .

Howdy Folks!

This is what happened in class today (9-22-97). As usual, all of this is in outline format with hypertext, so if you want to review the specifics, or if you have any questions on a specific topic, click the hypertext for that topic.

Today's topic:

The Mechanics of Breathing

Consequently, we'll discuss compliance, the pleural space, hysteresis, surfactant, and the LaPlace law.

Okay, continuing on from Friday's lecture , we resume the discussion of acid-base status and disorders. Please, please, please, make certain you know these things before the exam on October 3rd:

Also, you probably oughtta know what causes these disease states. Also, be familiar with the concept of base excess.

Oh, and before the exam, I'd make darn sure that I knew how to find pH, HCO3- or PCO2 using the Henderson-Hasselbach Equation .

Now, the new stuff:

(These topics will be finished by Wednesday, October 1):

A copy of today's nifty handout:

Figure 1

Figure 2

The text reads:
Measurement of the pressure-volume curve of excised lung. The lung is held at each pressure for a few seconds while its volume is measured. The curve is nonlinear and becomes flatter at high expanding pressures. Note that the inflation and deflation curves are not the same; this is called hysteresis .

Figure 3

The text reads:
Comparison of pressure-volume curves of air-filled and saline-filled lungs (cat). Open circles, inflation; closed circles, deflation. Note that the saline-filled lung has a higher compliance and also much less hysteresis than the air-filled lung.

Figure 4

The text reads:
Relaxation pressure-volume curve of the lung and chest wall. The subject inspires (or expires) to a certain volume from the spirometer, the tap is closed, and he then relaxes his respiratory muscles. The curve for lung + chest wall can be explained byy the addition of the individual lung and chest wall curves.

And, I thought it might help if you could see