 Drastic. Hey, everybody, Dr. O. This video I'm going to cover the beginning and end of the mechanisms of pathogenicity. So we're going to talk about the portals of entry here, then we're going to talk about the portals of exit because they're so closely related. So I brought this up in the introductory video, but the most, so the portal of entry is just the way in, right? Organisms generally have preferred portals of entry. The portal of entry they prefer is usually the one that's closest to the cell type where they're going to do their damage. Unless they're an organism whose goal is to get into your bloodstream and then they can really, they can travel anywhere. But the most common portals of entry and you should know these would be the mucus membranes. Specifically, number one, the mucus membranes lining the respiratory system. Number two would be the mucus membranes lining the digestive system. And number three would be the mucus membranes lining the genital urinary system. So why would these be the most common? I mean, these are passageways directly into and out of our body, but respiratory, think about that every time you breathe, every time you inhale, there's a possibility that you just picked up some droplets or airborne organisms and then digestive system. Every drink, every bite of food potentially can be carrying pathogens with it. So that's why they are clearly the most common portals of entry. Other portals of entry, so you just see a few examples here like the nose and the mouth. They would be the beginning of your respiratory and digestive systems. You just see the placenta, I'll cover a separate video over the types of organisms that actually can cross the placenta because the placenta is a pretty good barrier. It can keep most pathogens out, but there is a list. They're called torch infections. There is a list of organisms that can actually cross the placenta. So the first one I think of, it's not even really one of those torch infections, but the listeria, which is why pregnant women need to avoid deli meats and other foods where you normally don't have to be concerned because this listeria can cross the placenta and lead to spontaneous abortion, et cetera. So we see the ears and the eyes. These are going to, you know, the eye is covered with the conjunctiva, which would be, which would basically be a mucous membrane. You don't think of some of these as much, but they are common ways in. You have the urethra and both males and females. You have the anus, vagina, and then you see the skin. So the skin itself can be the location of a pathogen. It wants to get to the skin. Some organisms can actually get through intact skin, but you'll notice that most of what you're seeing on this image is broken skin. So this is called the parentaral route of a portal of entry. It's when you bypass either the skin or the mucous membranes. So you see like a needle or a needle stick injury here. You see an insect bite from a biting insect, or you see broken skin, right? So broken skin has lost this barrier. That's why like in the microbiology lab, if you have intact skin, you don't have to worry about things, but broken skin, you have to have you covered with bandage and wear gloves, et cetera, et cetera. So all right, so these are the most common portals of entry. So the key thing here, we see the portals of exit. The key thing to note here is that the portal of exit that a microbiome uses is almost always the same as the portal of entry. So if you are, if you cause foodborne illness, you generally come in the beginning of the GI tract and you leave in fecal material at the end of the GI tract. If you're a respiratory disease, you come in and exit the same system. So just looking at a few of them here, obviously you see like things you might not think of as much like tears, breast milk. These would be examples of things that can be infectious, that can spread disease. We'll talk about the placenta again separately. Skin itself can actually spread disease when you have the broken skin again. So blood coming out of broken skin, biting insects, needle stick injuries, these types of things. So yes, even earwax can actually spread disease. All right, so these are the portals of exit, which are almost always the same as the portals of entry. So that's going to be how an organism finds its way into you and then how it spreads from you to your neighbors, to other hosts. And that the portal of exit is so important because an organism doesn't want you to be its dead end. You know, making you sick, doing what it has to do inside of you is one thing, but it has to spread its offspring into the environment, into neighboring people. So that's how this works. All right, so those are your portals of entry and portals of exit. I hope this helps. Have a wonderful day. Be blessed.