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Current time:0:00Total duration:7:56

Video transcript

before we start to talk about one cancer I want to talk about the basics of the lungs the lungs are made up of lots of Airways that branch and every time they branch they get smaller and smaller and smaller and smaller and eventually they end in these sacs called alveoli they end here because at the alveoli is where gas exchange occurs with the blood that I'm drawing in red to represent the capillaries where blood is flowing but all these branched Airways need to be protected from everything else that's in the body cavity and so there's a lung lining that's made up of sheets of cells that form the boundaries of the lungs and keep everything well contained and immediately around the low lining is this protein rich fluid and this fluids pretty important because when you take a breath in your lungs expand and when you breathe out they contract and so there needs to be a way to accommodate this change in the size of your lungs and this fluid helps to do that but we don't want fluid just seeping into the body cavity and so it also needs to be contained and that means that there's another lining on the other side of the fluid keeping it well contained let's go back to the Airways for a minute because the airways are supported by lung tissue and if we take a section of them here I will explain more what I mean so let's draw some cells here and these cells are very close together and they're actually kind of glued together and they have a special name called epithelial cells and they set up the borders of the airway so here I'm drawing a little squiggly white line to represent air that's going to be flowing through this airway and on the other side of the epithelial cells is where the lung tissue is so you can already see that these cells are anchored to the tissue and help to keep the structure of the airway I'm going to come back and talk about more of the proteins and the structures that you would find in the lung tissue but for a minute let's just focus back on those epithelial cells let's just imagine for a minute that one of these cells becomes damaged your mutated and starts to grow controllably and that's really important because that's one of the things that defines cancer cells from other cells in your body there's just no way to stop them from dividing and to accommodate more and more cells these cancer cells start to push in on the airway and they also start to push in on the tissue underneath them taking away space from both of these areas in the airway this is a problem because air can't flow nicely through these Airways anymore and lung cancer patients are going to wheeze as a result of that and they're also going to feel a decrease in lung function and that decrease might not be so bad if the cancer is in a smaller airway but if this is in one of the main Airways of the lungs this can really be significant now the air that we breathe carries with it a lot of dust and bacteria and when the bacteria gets deep into the lungs may be difficult for a lung cancer patient to remove the bacteria again past the cell mass and so this sets up a perfect environment for the bacteria to settle down and cause a lung infection so the body is going to mount an immune response and they're going to send white blood cells to the site of infection to try to kill the bacteria and clear the infection so here's my white blood cell and it's traveling through the blood and the vasculature actually becomes leaky allowing this white blood cell into the lung tissue to travel up to the bacteria so that they can actually kill the bacteria but during this process of the white blood cell migrating out of the blood vessel fluid is going to follow it into the lung tissue that's my yellow yellow lines there and the lung tissue is going to start to swell with this fluid and you can imagine that that means that all the lung tissue is going to be pushed out further into the airway so I'm going to draw that with with dotted cells here to show you the movement of cells into the airway and that's going to increase all of the symptoms that the lung cancer patient it's already experiencing with getting air in and out of these Airways but not only is the immune system responding to the lung infections it's also responding to the lung cancer cells themselves because the immune system recognizes them as foreign and with all this activity lung cancer patients will run and going fever as a response from a chemical secreted by the immune cells as they respond and so the immune system is really running a marathon here and requires a lot of energy unfortunately patients have trouble keeping up with these energy demands and this contributes to an unintentional weight loss but let's go back to the lung cancer cells for a minute because these cells me a few things that are not typical of other lung cells one of which is an enzyme that breaks down tissues around the cells and this allows cancer cells to invade the lung tissue and surrounding structures nearby and if they migrate to vessels like our blood vessel down here they can gain access to them and travel throughout the body to other organs in a process called metastasis metastasis and form secondary cancers of these sites lung cancer cells can also migrate into the lung lining like we had discussed in the beginning let's go back to though our image here they can migrate through the lining of the lung where that protein rich fluid cradling the lungs is located and an immune response to cancer cells here is going to be a lot like what we just saw it's going to cause swelling and the swelling is going to take up space from the lung and make it even more difficult to breathe so now that we know the reason for a lot of signs and symptoms associated with lung cancer you might be wondering what actually causes a cell to become cancerous in the first place and this is a really good question because I kind of just brushed over the fact that the cell becomes spontaneously mutated but in lung cancer there are three main causes of mutations one of which is smoking and in fact smoking is so strongly tied to the development of lung cancer there's actually a unit of measure to determine how at-risk a person is depending on how often and how long they've smoked for and this unit of measure is a pack here and that means let's say a patient has been smoking about 20 cigarettes a day that's equivalent to a pack of cigarettes a day and you know what let's say this person smokes three packs of cigarettes a day and they've been doing this for 10 years so this person would have been smoking three packs per day times 10 years for an equivalent of 30 pack years and 30 pack years is an important number because it places this person and a very elevated risk of developing lung cancer another mutation source is radon and radon is a naturally occurring gas that you find in the atmosphere but we're breathing in all the time do you explain where a comes from I'm gonna draw tree rooted in some soil and maybe a house on top of the soil and in this soil is a chemical that when it breaks down it releases this colorless odorless gas called radon into the environment and it can become trapped in houses and particularly in basements in houses and it builds up that high enough concentration so this can cause lung cancer and finally a main last source of mutation in lung cancer is medical imaging and if a person goes to the doctor needs to have a picture taken of the inside of their chest it might be taken you with the use of radiation in the form of x-ray or a computed tomography scan which you may be more familiar with as a cat scan but either way this person is receiving a large dose of radiation that can be harmful to their cells and to give you an idea of the radiation dose you were to take a plane ride from New York to California that's a livers about half the radiation that an x-ray does and then CT scan delivers about a hundred times the radiation of a single x-ray