 Hey everybody, I'm Lance Goyke and today we're going to talk about partial pressures Oxygen how the lungs interact with the blood system and why oxygen is so important So let's start with the last one. So oxygen is really important because without oxygen You die in like five minutes because your brain needs it to work. You need Oxygen to produce large amounts of usable energy. So as as we go through glycolysis We enter the mitochondria. We go through the citric acid cycle We get to the electron transport chain at the very end of that electron transport chain oxygen is the final acceptor of Electrons and this is this whole system has been pushing electrons around because we use these Electrons and this electro motive force or proton motive force that we might say to make usable Energy so we put another phosphate group onto a diphosphate and adenosine diphosphate to make a Tp or adenosine triphosphate and we use that to produce energy or to accomplish tasks or to transport Neuro transmitter vesicles back to this cell body and back and forth and whatever so all sorts of stuff I'm also contraction. That's a huge one. It's a huge source of ATP usage So we need this oxygen, but how do we get it to the tissues? Well first it needs to get to the blood because the the blood or the circulatory system is the system that delivers it transports all of these nutrients and gases and whatever Now to talk about the blood we need to then first talk about the ventilation or the respiratory system So the respiratory system is much more complex than just inhaling and exhaling just simple ventilation We would call that that's the distinction there. So respiration also involves the exchanging of molecules and ventilation is simply inhaling and exhaling so To fill the lungs. I have pressures. I need to manage pressures If I have a total pressure inside my lungs, it's comprised of multiple different molecules So to simplify it there are other molecules but to simplify it we're going to say we have a partial pressure of oxygen and a partial pressure of carbon dioxide and That forms one total pressure inside the lungs If I take a breath of fresh air That partial pressure of oxygen is relatively high because I haven't used all of that oxygen at the end of my electron transport chain like we talked about and the freshly inhaled air, the Partial pressure of carbon dioxide is relatively low But in the tissues, especially if I've been holding my breath for a really long time and I'm working out really hard That oxygen becomes depleted those oxygen levels lower and the carbon dioxide levels raise Now to understand what occurs next we need to understand Gradients which if you've gotten this far in physiology you've probably heard of gradients we have Different it's like it's like a hill like a ball rolling downhill. That is a height gradient We might talk about Membrane potential or electrochemical gradient in neurons or Just simply particle gradients so if I have a lot of oxygen in one side and a little bit of oxygen in the other side Then I want to use that To roll downhill roll the ball downhill. So we're going to roll the oxygen into the low concentration place In our example, we have high concentration of oxygen Lots of oxygen in the fresh air and less oxygen in the blood this tired blood because I'm working out Right. I've been churning through this stuff Whatever exercise or even just I'm sleeping really hard or whatever because it takes energy just to live That's why you die without oxygen, right? Okay, so we're bringing it all together. We take these gradients and We we just flip-flop it for the carbon dioxide. So carbon dioxide is high in the blood It's gonna flow out of the blood now because there's too much there. We need to even it out This again comes to thermodynamics. So this is why you learn all these basic principles Thermodynamics wants more stable systems so if I have too much of one thing and Too little of another thing. I'm gonna try to even those pressures out and this drives that exchange of oxygen and carbon dioxide to Get to ventilate I need to also monitor the pressure of my thoracic cavity. So To decrease the pressure again, we're creating a gradient I if I want some air to flow into my lungs Do I need higher pressure in my lungs or lower pressure in my lungs? I need lower pressure in my lungs. I need a high pressure outside a low pressure inside So how do I lower the pressure in my lungs? Well, I can take the volume of my thorax and increase it Okay, so the principle is that there are the same number of particles in this container But if I make the container bigger it makes sense that the pressure is lower, right? So that's that's the basic principle of ventilation of Gradients applied to different particles and gas exchange If you have any questions Leave them in the comments below Because I like to respond to those and I like to hear what you guys are thinking if I've left anything unclear If I've said anything incorrectly, let me know I think I got it all but if there's something I miss that you think I should touch on just let me know and Don't forget to smash that like button