## Biomedical Engineering 403 Mechanics of Breathing, Part 1

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

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

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

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

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

# Dr. Yamashiro's Handout from Last Year!

It's the same material, presented with more detail and explanation.

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Pretty much just what is sounds like. Brought to you by the Johns Hopkins School of Medicine.
Pretty much just what is sounds like. Also brought to you by Johns Hopkins.
A list of links to the rest of Johns Hopkins' respiratory physiology web pages.

#### And that's it for today!

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