Biomedical Engineering 403 Gas Laws and Their Application

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Hi there!

El Duggo here.

FYI, these pages will be under continuous construction. I'll add stuff as it comes to me, as I find new links, better ways of explaining the material, or as people with questions beat me into submission. So if you don't find what you're looking for on the page now, check back again in a day or to to see if the page has been updated. And of course, always feel free to ask me questions. Also, if you have suggestions as to what should be added to these pages, please let me know.

And remember, you can always e-mail me.

Page 168 in West

Also, Dr. Z gave us a couple of handouts. Both of them are labelled "Chapter 2." One of them is chapter 2 from West, but I don't know where the other one comes from. If you don't have the handout, please check in the BME office in OHE 500. I hesitate to put the handout on the web since it looks like it's been copied out of a textbook, and, well, you know how picky those textbook people are about their copyright laws.

The nitty gritty:

Here's the 411 on today's lecture. For the specifics, check out the hypertext.

When we breathe, air goes in and out of our lungs. We wanna be able to take a certain volume of household air, suck it into our lungs, and calculate how much oxygen gets into our blood as a result. Let's break this down:

• Ordinary air is made up of a collection of gases, and if we wanna quantitatively describe the events that occur in respiration, we better have some equations that tell us how each of those gases behave under different conditions.

• We gots gas laws! These are equations that describe the behaviors of gases in terms of the relations between their pressures, temperatures, and volumes. Know these, as I predict that they will show up on the exams.

• The ideal gas law tells us how individual ideal gases behave. For example, we may look at a volume of pure oxygen and use the ideal gas law to calulate the pressure at a given temperature. But room air is a mixture of gases, and inside the human body, we never ever ever deal with pure gases. So, we need to know how to deal with mixtures of gases. Towards that end, we discussed:

• Well, now we know how to calculate volumes and pressures and temperatures for mixed gases like air. But once we suck that air down into our bodies, it gets wet! The human body is absolutely soaking wet! All that water sloshing around in our blood fills the lungs with water vapor. In order to compensate for that in our equations, we need to deal with the effect of water vapor (a gas) on the pressures and volumes of air in the lungs. Know these concepts cold (they WILL come back to haunt you):

• Do you know what a Spirometer is? You should, before the exam.

• Finally, you chould know Henry's Law.

That was pretty much what he covered in lecture today. Remember that you're also responsible for the stuff in the handouts.

Study hard. Don't watch too much football this weekend. Hasta!