Pathophysiology of chlamydia | Infectious diseases | NCLEX-RN | Khan Academy

Pathophysiology of chlamydia | Infectious diseases | NCLEX-RN | Khan Academy


– [Voiceover] Pathophysiology
is the study of how a disease occurs. And so if we’re talking
about the pathophysiology of chlamydia, we’re talking about how this bacterial organism hijacks
the cells of our body to multiply and cause an infection. Now the unique thing
about chlamydia is that it’s not a very powerful organism that carries a lot of its own nutrients. It relies on the nutrients of
the host cell that it infects. Which means that chlamydia
must live inside of the host cell in order to reproduce and survive. So the way I’m gonna start
off designating chlamydia will be in green. So this initial green dot
right here actually has a very fancy name. This is referred to as an elementary body. An elementary body. Which is just a fancy way of saying it looks like a dot. So the first step of
chlamydia infecting our body is that it needs to somehow enter a cell. And the way that works is
because of our white blood cells. So I’ll draw this guy right here, make him look rather ferocious with these red teeth right here. Now this white blood cell is similar to most cells in our body
in that it has a nucleus. So I’ll draw this nucleus up here. And this is where all the
genetic information for the cell on how to survive and
make proteins is stored. So when a white blood cell
sees this elementary body, this unusual particle that
shouldn’t exist in our body, it wants to eat it. And this process by which
this white blood cell swallows the elementary body, or
any foreign particle, is referred to as phagocytosis. Phagocytosis. Where if you’ve heard this
term before you might recognize that cyt just means cell and phago is just a fancy way of saying to eat. So this cell is eating
this elementary body. And after a nice big gulp, you’ll see that the elementary body is now
contained within this vesicle. We can also refer to it as a phagosome. A phagosome. Some just means a body
that has been eaten, phago. And I just want to point out, I know I drew it as a cartoon here, but the teeth are actually
the cell membrane lining of the white blood cell
that sort of envelops around the elementary body to
turn it into this pocket, this phagosome within the cell. Now, once the chlamydia elementary body is within the white blood cell, it’s game time. Now it uses whatever nutrients it has within this dinky little dot, and let me just redraw the
white blood cell right here. This dinky little dot will convert from an elementary body to this
guy that looks like a star. And because it looks like a star, scientists refer to this
as a reticulate body. A reticulate body. and that’s just a fancy
way of saying reticular, or reticulate means a star. Now once the chlamydia has
turned into a reticulate body, it’s going to use the nutrients
the white blood cell has. So here’s our white blood cell, and the phagosome that I’m
going to purposely draw larger. And the phagosome will have
a lot of reticular bodies, because these will
start using the proteins and the machinery that the cell has to reproduce itself with binary fission, meaning it just splits in half. So I’ll write that term over here. This is using binary fission, where you take something that grows and just cut it in half and now you’ve got two smaller versions of it. Binary fission. And while all this is happening, we’re directing nutrients the
cell should have been using to fortify its cell membrane, to get nutrients from the outside, towards the chlamydia. So you’ll notice that it doesn’t look like it’s doing too well. I’ll draw the nucleus
very small to indicate that it’s not having a great time here. And once we’ve made
enough reticular bodies and we’ve reproduced enough, the chlamydia will decide that it’s time to infect another cell. So here’s our white blood cell again. And I’ll draw an even larger endosome, it’s ridiculous how big it is, and there are these reticulate
bodies that are here still that we have reproduced. But in addition to the reticulate bodies, we’ve started making elementary bodies, these infectious forms of chlamydia. So the elementary bodies
are the infectious version of chlamydia,
the reticulate bodies are the growth versions of chlamydia. That’s a good way to think about it. And so these guys start mass
producing within the cell. And the cell is not
having a good time now. It is basically on the verge of death because we are not using our nutrients to fortify and grow this cell membrane or to generally help it survive. So as a result of this, the
cell will literally pop. It will burst open and rupture. It will rupture and therefor die, causing the reticulate
bodies that were converting, as well as the majority of
the chlamydia organism now in elementary bodies to be released into the extracellular matrix. To be released outside of the cell. And you’ll have some
reticulate bodies, of course, but you’re going to have a
majority of elementary bodies that can be picked up again
by another white blood cell and we can repeat this cycle. Another variant of this you might see is instead of a white
blood cell swallowing up these elementary bodies, you might have an epithelial cell. So I’ll write epithelial cell here. Like the epithelial cells
that line the vagina or even line the urethra. That can swallow the
elementary bodies by a process known as endocytosis, which is really just an umbrella term for phagocytosis. Phagocytosis is a type of endocytosis. And doing that will produce and endosome. An endosome. And the rest of the cycle is all the same. Especially the very
unfortunate outcome right here. So this is how chlamydia will spread from cell to cell and
make it’s way further up the genital or the urinary tract.

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