Matinum

Taking Charge of Your Health


So by this point, you’re probably aware
that your body needs oxygen to survive, right? In fact, every cell in your body needs that
precious oxygen. Those cells use the oxygen to produce energy
in the form of ATP, or adenosine triphosphate, a super super important molecule, sometimes
even called “the molecular unit of currency”. The cells use it to basically pay the molecules
inside the cell to do their specific jobs. It’s like one big factory with a bunch of
workers that all have specific jobs needed to run the factory, and they only take ATP
as payment. Now the mitochondrion of the cell takes in
oxygen and makes ATP to pay the workers, through a process called oxidative phosphorylation,
the mitochondrion’s like the factory’s payroll department, right? When the cell doesn’t get enough oxygen,
and so payroll can’t produce the ATP that they need to pay the workers to do their jobs,
the whole cellular factory can be damaged or even die, and we call that process hypoxia,
where hypo means “less than normal” and oxia means “oxygenation”. When the oxygen comes in, typically it goes
straight to payroll, specifically to the inner mitochondrial membrane where oxidative phosphorylation
takes place. Oxygen’s used in one of the last steps,
and serves as an electron acceptor, and this allows the process to finish and produce ATP. So without oxygen, we can’t finish oxidative
phosphorylation and produce ATP. But why does the whole factory fall apart
when payroll stops making ATP? Why don’t they just pause for a bit? Take a little break? Well, when certain workers stop doing their
jobs…things get a little out of hand. One super important worker is the sodium potassium
pump on the cell’s membrane, pretty much like the bouncer that makes sure there isn’t
too much sodium diffusing into the cell, basically by pumping it back out every time it diffuses
in and maintaining a concentration gradient, this process also keeps too many water molecules
from passively diffusing into the cell; think of it like this: water molecules want to go
every which way and are constantly moving back and forth, inside and outside the cell,
but the all these sodium ions on this side tend to physically block more of them from
leaving that side, so over time more water molecules get retained, or almost trapped,
on the side with more sodium—in short, the more sodium molecules: the more water molecules. But, our pump doesn’t do all this for free,
and it needs ATP. So without ATP, it stops pumping sodium back
out, and sodium diffuses in…and keeps diffusing in and the concentration gradient goes away,
now with less sodium particles on the outside blocking the water molecules from going into
the cell, water follows sodium in, which causes the cell to swell up. When the cell swells up, a couple things happen. First, usually you have these really tiny
microvilli on the cell’s membrane, which look sort of like little fingers that help
increase the cell’s surface area and therefore help the cell absorb more things, when the
cell swells up and gets all bloated, the water sort of fills these little fingers and reduces
the surface area, which makes it harder to absorb molecules since there’s less surface
area, right? Also, sort of along the same lines, the cell
can bleb, or bulge outward from all this water, this is a sign that the cell’s cytoskeleton
or this structural framework is beginning to fail, and is letting water slip through. Finally, the rough endoplasmic reticulum,
or the rough ER, also swells when the cell swells. And remember that the rough ER has all these
little ribosomes on its outside, and these are really important for the cell in making
proteins, but when the rough ER swells, they detach, and stop making proteins, so protein
synthesis goes down. All the ATP isn’t immediately lost though
when you lose oxygen and oxidative phosphorylation stops, luckily your cell can make ATP another
way, called anaerobic glycolysis, anaerobic meaning in the absence of oxygen. This is like the backup ATP generator, which,
isn’t nearly as efficient and only produces a net of about 2 ATP molecules per glucose,
whereas oxidative phosphorylation makes about 30-36… So it helps a little, but what also happens
is it produces the byproduct lactic acid, which lowers the pH inside the cell. This more acidic environment can denature
or essentially destroy proteins and enzymes. Now, up to this point, it’s not all bad,
because one super important thing about these processes that happen to the cell, is that
they’re potentially reversible, meaning that if we all the sudden get oxygen again
and start making ATP, then these changes aren’t necessarily permanent. After enough time, though, irreversible damage
can happen to the cell. Kind of like the sodium potassium pump, there’s
also a calcium pump that helps keep too much calcium from getting in, and if that stops
working, then calcium starts to build up, which isn’t a great thing. First, calcium can activate certain enzymes
that you might not necessarily want to activate, like proteases that can slice up proteins
and damage the cell’s cytoskeleton, which remember is the structural framework that
keeps the cell together. Also, endonucleases can be activated, which
can cut up DNA, the cell’s genetic material. And if we get back to thelactic acid, as more
lactic acid builds up and the environment gets more acidic, the lysosomal membrane can
be damaged as well, which usually houses these hydrolytic enzymes whose job is basically
to grind up large molecules, and when they get out, well, they’re also activated by
calcium and then they just start cuttin’ everything in sight, and basically start digesting
the cell from the inside. Finally, the phospholipase enzyme, which basically
splits phospholipids, gets activated…since the cell’s membrane’s made of phospholipids,
these can destroy the cell membrane, which is probably the most important sign of irreversible
damage. When the membrane’s destroyed, those enzymes
we just listed, along with others, can leak out into the blood and continue wreaking havoc. Finally, let’s jump back to calcium. Enzyme activation isn’t the only effect
calcium can have; calcium can get into the mitochondria, causing a cascade the leads
the mitochondrial membrane to be more permeable to small molecules and so it lets a molecule
that usually stays in the mitochondrial, cytochrome c, to leak out into the cytosol. This is a big big red flag to the cell that
things have gone south, and is kind of analogous to the self-destruct button, and activates a process called apoptosis,
or programmed cell death. This is a bit like cellular suicide. At this point, the cell’s not in good shape,
right? And all this happens eventually because of
a lack of oxygen, or because of hypoxia.

90 thoughts on “Hypoxia & cellular injury – causes, symptoms, diagnosis, treatment & pathology

  1. We've updated this video. In Anaerobic Glycolysis –2 ATP are produced per GLUCOSE (not per Oxygen as mentioned in the original video )

  2. Question: You're saying that the sodium molecules "physically block" the water. I struggle to understand this analogy, since sodium itself is dissolved in the water. Also, as far as I know, water is kept in the extracellular solely because of osmosis? What you've described sounds more like some kind of substrate inhibition.

  3. Hypoxia is a process which slowly becomes irreversible if not tacked in early stages  ( like in the case of an MI )  and  the  end result is cell death . A good clinical   pathological correlation would be with the 4 types of Hypoxia  fundamentally explained. Thank you for posting . Great Job .

  4. So amazing! I'm in my 4th year of the career in Venezuela and there are things that you remark on some videos that my teachers say and are not actually in the books. Great job guys!

  5. Brilliant! I'm a neonatal nurse trying to produce some teaching material on neonatal hypoxic ischaemic encephalopathy and how therapeutic hypothermia and xenon gas work. There's plenty of literature on this, but it's written for doctors, who have a better understanding of the background physiology than I have. I think I'm now getting the picture! Believe me, I'm deeply grateful.

  6. ive had it and it has caused damage to my blood cells anf now im not able to produce any white blood cells anymore

  7. I never comment on videos but wanted to let you know that this was well explained and well illustrated. It helped solidify concepts that I need to know for school. I will probably check out your other videos in the future. Keep up the good work!

  8. Can we all agree once and for all that asphyxia and hypoxia are the same fucking thing, and don't even try to define asphyxia as lack of oxygen due to impaired breathing because it's the same thing as hypoxic hypoxia .

  9. Me: decides to use something other than Khan Academy to study for once
    Also me: Finds myself on a YouTube video narrated by the same guy 😂😂😂

  10. Edema is a characteristic for Necrosis. When Apoptosis happens to a cell, it shrinks instead of swelling 🙂

    Check it out in Robbins in it's 9th edition.

  11. I lost my mum to this tonight. She wasn’t breathing for over 10 minutes and suffered massive brain damage. Started by a cardiac arrest. It’s been the worst 48 hrs of my life.
    I can’t believe what’s just happened.

  12. Such an amazing video!!!!
    So simple, but powerful. I don't know how to thank you, I was wandering around browsing internet throughout the day to make clear about this subject. And now iam cleared all my doubts regarding hypoxia .
    Such an useful video, always keep supporting..

  13. I'm a fan of your videos in general but I have to the animation and narration for this video was spot on! Very effective.

  14. That was very helpful. I've watched a couple of your videos as I take Pathophysiology and it is helping me understand. Thanks for your help!

  15. Oh my fucking god bitch,,,,,, I HAVE BEEN SLEEPING IN A 24 BURGER KING AND MCDONALDS FOR TWO FUKING DAYS JUST TOREAD A WHOLE ASS ELSEVIER AND BIG BOY MEDDICTIONARY JUST TO WRITE A FUCKING SMALL ASS PARAGRAPH OF WRAP UP THAT DOESNT EVEN MAKE SENSE FOR MY PBL SCENARIO

    BITCH I JUST WATCHED THIS AT 4 AM BFORE DUE DAY??????
    FUCK YOU

    FUCK YOU

    OH MY FUCKING GOD

    IM A DUMBASS OH MY GOD OH GOD I SLEPT AT MCDONALDS FOR FUCKSACE I ALMOST DIED YOU BITCH

    IM SORRY IM OVER REACTING BUT YOU LITERALLY SAVED MY FUCKING LIVE BITCH OH MY GODFD

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