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Current time:0:00Total duration:12:36

Video transcript

most cells in the human body just go about their business on a daily basis in a fairly respectable way let's say that I have some cell here this could be maybe a skin cell or really any cell in any tissue of the body and as it as that tissue is growing or it's replacing dead cells the the cells will experience mitosis and replicate themselves make perfect copies of each other and then those two maybe will experience mitosis and then if they realize that gee you know it's getting a little bit of it's getting a little crowded there are other cells in my neighborhood there are other cells in my neighborhood they'll recognize that and say you know I'm going to stop growing a little bit that's called contact inhibition contact inhibition and so they'll just start going and then let's say one of them experiences a little defect a little defect and he says you know what gee you know I'm I'm not really you know something is a little bit wrong with me I the cell recognize this in myself and the cells will actually kill themselves that's how the good of cellular citizens they are they'll kind of make way for other healthy cells so this guy might even kill himself if he realizes that there's something wrong with it there's actually a cellular mechanism that does that's called apoptosis and I want to make this very clear this isn't somehow some type of outside influence on the cell the cell itself recognizes that it's somehow damaged and it just destroys itself so a pop ptosis so that's the regular circumstance even when there is a mutation and just to give you an idea even if mutations are relatively infrequent and I don't know the exact frequencies at which mutations occur I suspect it's of different frequencies and different types of tissues there are on the order of on the order of a hundred billion one let me do a different color they're on the order of 100 billion new cells in the human body per day per day so even if you only even if the mutation only occurs one in a million times you're still dealing with roughly 100,000 mutations and maybe most of the mutations you know maybe they're just some little random things that don't really do a lot but if the mutations are a little bit more severe the cell will recognize it and destroy itself and I want to make a clear a very clear point here I'm talking about the cell the cells of the body or most of the body this could be the cells in my in my eye or the cells in my brain or the cells on my on my leg these aren't my germ cells so these mutations even if the cell survives will not be passed on to my offspring that's an entirely different discussion when we talk about meiosis these are all my body cells and they're replicating and we've gone over this with with mitosis mitosis so any mutations here they'll either do nothing or the cells might malfunction a little bit or the cells might hurt themselves or hurt me but they're not going to affect my offspring I want to make that point very clear now you're saying hey Sal 100 billion new cells a day I must you know that must mean like every cell in my body is recreated well and that just gives you an idea of how many cells we have we actually have on the order of and you know it's obviously not an exact number but there's actually in the human body there's on the order of 100 trillion cells 100 trillion cells and if you look at it that way you say on average 1000th of your cells replicate each day but the reality is some cells don't replicate that frequently at all in some cells replicate much more frequently but this just gives you I mean you know just to take a little side note here this gives you an appreciation I think for the complexity of the human body and we think of our own a world economy and world society is so complex it's made up of six billion humans we're made up of a hundred trillion cells 100 trillion let me rewrite 100 trillion in billions 100 trillion can be rewritten as 100,000 billion cells and each one of those hundred thousand bili billion cells are these huge auto - we shouldn't use the word hughes but there's these complex they're these complex ecosystems in and of themselves with their nucleus is and we'll talk about all the different organelles they have and we talked about cellular replication DNA replication and how the cell replicates so these things aren't jokes and they have of these you know these complex membranes that take things into them and you know that they are creatures to themselves but they live in this complex you can almost view an environment or society that is that is each of us so that's just a side note just to appreciate how large and how complex we are but you could imagine as and this is how I got off on this tangent if we're making on the if we're making on the order a hundred billion new cells every day you're going to have a lot of mutations and maybe some of the mutations you know I said some of them don't do anything some of them the cell recognizes that the cell is just going to be kind of you know dead weight so the steps the cell kind of eliminates itself but every now and then you have mutations where the cell doesn't eliminate itself and it also deforms the cell so when you have that let's say I have some cell here I have some cell and it's got some mutation I'll do that mutation with a little with a little X right here with a little X that's it's an in DNA maybe it's got a couple of mutations so one of the mutation keeps it from experiencing apoptosis or destroying itself and maybe one of the mutations makes it replicate a little bit faster than its neighbors so this cell through mitosis and makes a bunch of copies of itself a ton of copies of itself and this kind of body of cells this body of cells that essentially has a defect they're all from one original cell that kept duplicating and then those duplicating but all of these are defective cells if you were to look at them and in kind of a you know on compared to the tissue around it it would look abnormal in some way maybe it wouldn't function properly this is called a neoplasm neoplasm neoplasm now a lot of neoplasms well they don't have to form a body like this sometimes they might somehow circulate in the body but most of the times they form this kind of this big lump and if they get large enough they're noticeable and that's when we call it a tumor so if this is if this is actually a lump a lump of kind of differentiate of tissue that's definitely abnormal that what you call a tumor so the term neoplasm and tumor are often used interchangeably tumor is the word we use more in our everyday vocabulary now if these kind of if this lump just kind of grows to a certain size but it doesn't you know it's just there doesn't really do anything dangerous it's not it's not it's not replicating out of control I guess it's not replicating a lot faster than its neighboring cells and it's just hanging out maybe growing a little bit but and not in any significant way harming our environment we call that a benign tumor or benign neoplasm benign and benign essentially means harmless benign tumor that means if it's you know that's that's good you want to hear that if you got a lump god forbid you you have a lump either way but if you do it's a benign tumor that means you know that lump it could kind of stick around no damage done but if these if these if these DNA mutations maybe some of these are it is benign but maybe one of the benign ones has another mutation in it that starts making it grow like crazy grow like crazy and not only does it grow like crazy but it becomes invasive and invasive means that it starts it doesn't care what's going on around it it just wants to infiltrate everything so let's say that guy grows like crazy and he starts let me do in a different color and he starts infiltrating other tissue so he's invasive invasive so super growth super growth he's invasive so he starts he doesn't care what's going on he said all of a sudden turned into some type of cellular psychopathy and even worse his descendents it's not just one cell anymore he just keeps duplicating and passing on this kind of a broken genetic information that makes it want to replicate and then maybe more even more you know there could be more and more things that break down in its I guess offspring or the the DNA that comes from its for applications and actually that's that's a good likelihood because the same parts of its DNA that broke down some of the some of the DNA that that broke down and this guy some of the mutations might have actually hurt DNA replication scheme so that mutations become more frequent so more frequent mutations more frequent so as Z as these replicate more and more mutations appear and then maybe eventually one of them you tations appears that allows these cells to break off break off and then travel to other parts of the body to travel to other parts of the body and then in those parts of the body start to take over and start taking over all of the cells and this process is called the the cell has met at this is one of the hardest words for me to say something wrong with my brain but the cell has metastasized metastasized you might have heard the word metastasis and that's just the notion of these these run amok cells all of a sudden all of a sudden being able to travel to different parts of the body and I think you guys know what we call these cells these cells that aren't respecting their cellular neighborhood they're growing like crazy they don't experience that contact inhibition they're invasive they they start they start crowding out other cells and hogging up the resources and they keep mutating really fast because they have all of these genetic abnormalities and eventually they might even break away and start infiltrating other parts of the body these are cancers or cancer cells cancer cells and so you might have an appreciation for why this is so hard cancer is such a hard disease to to quote/unquote cure because it really isn't just one disease it's not like one type of bacteria or one type of virus that you can pinpoint and say let's attack this cancer is a whole class of mutations where the cells start exhibiting this fast invasive growth and this metastasis so you know you might look at one type of cancer and be able to say hey let's target you know the mutation that where the cell where the cells look like this and you're able to knock out you're able to knock out some of them let me do a this in this color so maybe your Nabal to knock out that guy that guy that guy but they're the because their DNA replication system might be broken in some way they continue to mutate so eventually you have one version that's able to not be knocked out by whatever that you get and so you have this kind of new form of cancer and then that new form of cancer is even harder to kill so you can imagine that cancer is a it's kind of a never-ending fight and you kind of have to attack the general idea behind it when you when you chemotherapy and radiation all of these type of things they try to attack things that are fast-growing because that's the kind of one common theme behind all the cancers and we could do a whole playlist on you know what cancer is and how people are attacking it but I wanted to at least show you in this video that cancer really is just a byproduct of broken mitosis or bro or any even more specifically broken DNA replication that we have all of these all of these all of these cells replicating themselves every day you know on the order of a hundred billion and every now and then something breaks usually when they break the cell not either nothing happens or the cell kills itself but every now and then the cells start replicating you know even though they're broken and sometimes they restart replicating like crazy they just replicate but they're really not doing any harm it's a benign but if they start replicating like crazy taking over resources and spreading through the body you're dealing with a cancer so hopefully you found that interesting we already you already know a good bit of the science that kind of deals with what is probably you know one of the one of the worst ailments that we deal with is as as as creatures I mean obviously we're not the only people who can experience cancers even plants have cancers
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