Document MVjR8VvEjEZbX0m72354pq57

1 here, and I want you to think of it as like being Page 722 ; 2 suspended over a room and you are looking down into I 3 the room and looking at the rug on the surface and it 4 is a room without a ceiling. 5 You see, these are like -- each of these are 6 little rooms without ceilings on them, and so in the i 7 next slide we are going to look right down into this ' 8 space right here now magnified hundreds of thousands j 9 of times, and this is a human alveolar space. 10 What I want you to see is that the rug that 11 is covering the floor here, and I am actually pointing j \ 12 out one of the cells here, this is the border of a 13 single large flat cell, and here is another big flat 14 cell that runs around this way and then there are some j 15 smaller cells. 16 Now, this is called an epithelium. An j 17 epithelium is really just a big word for a cell that 18 covers something, so our skin is an epithelium and we ; 19 have epithelial cells covering our nose and the inside 20 of our mouth and all the way down our GI tract, and 21 these are cells now that cover the floor. I