LEC 7 - MCB 136 Professor Terry Machen Lecture 17 ASUC...

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MCB 136 Professor Terry Machen 3/17/09 Lecture 17 ASUC Lecture Notes Online is the only authorized note-taking service at UC Berkeley. Do not share, copy or illegally distribute (electronically or otherwise) these notes. Our student-run program depends on your individual subscription for its continued existence. These notes are copyrighted by the University of California and are for your personal use only. D O N O T C O P Y Sharing or copying these notes is illegal and could end note taking for this course. ANNOUNCEMENTS There are a couple of announcements. The midterm is on the Tuesday after spring break, March 31 . There will be a review session on Thursday at 7 pm in 101 Morgan Hall . This week I have extra office hours on Tuesday, Wednesday, and Friday from 5-6, and also my normal office hours. Many topics I hoped to cover I am skipping. There is a bunch of stuff in the notes and on the slides that have been omitted, and I will post the updated versions on bspace. LECTURE Last time we talked about ventilation. We talked about the different anatomical structures involved in ventilation: airways and bronchioles and such. Then we talked about alveoli, type 1 and 2 cells, and ventilation as negative pressure breathing, sucking the air in, which is the work of the diaphragm and the intercostal muscles. The diaphragm and intercostal muscles work together to expire. Expiration is passive. Inspiration requires some energy to overcome the springiness of the lungs. Compliance is intimately related to surface tension and surfactant (secreted by type 2 cells), which is important for reducing surface tension. This is explained in the Law of Laplace. It states that the pressure inside a sphere at a given wall tension gets bigger as the vessel gets smaller. The tension in the wall required to withstand a certain pressure is smaller when the radius is smaller. In this experiment, tension is defined by how strong this rubber is (of a balloon). The bigger balloon feels stronger, like it has more tension, than the smaller one. The size of the vessel is an important determinant for how much pressure it takes to blow it up. The airway resistance is the air going through the lungs, trachea, bronchi, bronchioles, etc. That’s the other thing you have to work against while inspiring. The dead space is a space in which there is no air exchange. There are probably other alveoli that don’t exchange also. The tidal volume (.5L per breath) times the frequency (12 breaths per minute) is going to be the total amount of air that goes out. The important ventilation is alveolar, which includes the difference between tidal volume and dead space. You have to take air past the dead space so the alveoli are ventilated. Now the gas has to dissolve in the water. It has
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This note was uploaded on 05/07/2009 for the course MCB 58168 taught by Professor Thorner during the Spring '09 term at Berkeley.

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LEC 7 - MCB 136 Professor Terry Machen Lecture 17 ASUC...

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