Hey guys, it's Medicosis Perfectionatus, where medicine makes perfect sense, and today we have a comparison video. Let's compare between apoptosis and necrosis. Apoptosis is a programmed cell death, necrosis is not. Apoptosis could be physiological or pathological, but necrosis is always pathological. With that said, now let's get started. There is a playlist on my channel known as Comparisons. One of the things that can help you become a great clinician is to learn the distinctions in medicine, instead of just reading the textbook as a mishy-mushmash. Cell changes are divided into cell adaptations, reversible most of the time, or cell injury, which could be reversible or irreversible. Let's talk about cell adaptations, mostly reversible. Example. Atrophy, hypertrophy, hyperplasia, metaplasia, dysplasia, and neoplasia. Don't forget, neoplasia could be benign or malignant. Malignant is called cancer. And of course, cancer is mostly irreversible unless you treat it, or remove it, or radiate it, or do whatever. Do some cancers go away on their own? Yes, some of them recede and secede, and no one knows why. Cell injury could be reversible or irreversible. Irreversible cell injury leads to cell death, and cell death is divided into apoptosis or necrosis. When I say apoptosis, please remember the groups of enzyme known as caspases. So let me classically condition you like Pavlov's dog. Okay, stimulus, response. Apoptosis, caspases. Apoptosis, caspases. Good boy. Apoptosis vs. Necrosis Apoptosis is cell suicide and necrosis is cell homicide, metaphorically speaking. Apoptosis, I did it to myself. Necrosis, I was overwhelmed by pathology. Causes of apoptosis could be physiological or pathological. Give me an example of physiological cause. Sure. Remember during embryology, my fingers had webs in between them, like this. Wow. So how did I end up with long fingers like I have right now? Because these webs, whoa, resended like this. Who, who, who, who killed them? Apoptosis, baby. Programmed cell death. Necrosis is always pathological, such as decreased perfusion, aka ischemia, due to a blood clot. What happens to the cell during apoptosis? It shrinks. How about during necrosis? It swells. Cell membrane forms blebs, we call them apoptotic blebs, without significant inflammation. However, necrosis, boom, severe, you have lots of inflammation, lots of inflammation, until your cell membrane gets destroyed and disappears, like the Thanos meme. The cell nucleus in apoptosis will have its chromatin condensed and fragmented, and you get a deeply eosinophilic cytoplasm, but a basophilic nucleus, condensed, baby. In necrosis, you have the famous pyknosis, karyorexis, karyolysis, nucleus shrinking, nuclear fragmentation, nuclear dissolution, like the Thanos meme. In apoptosis, the organelles will aggregate, but in necrosis, they will break down. In apoptosis, inflammatory reaction is absent, or at least very limited, insignificant. However, in necrosis, tons and tons of inflammation. That's why we always say inflammation and necrosis. Hemorrhage and necrosis. Have you ever heard of hemorrhage and apoptosis? Uh, never. How did we know that apoptosis took place? DNA laddering. What the flip is that? DNA fragments. Made of what? Multiples of 180 base pairs. Nitrogenous bases, that is. How about markers of necrosis? Well, there are no, like, official markers of necrosis, but let's think about it. Okay, in apoptosis, the cell death is programmed. The cell will form some blebs. and it will shrink on itself, and it will not leave a huge mess. But in necrosis, my goodness, the cell is destroyed. It ruptures, okay? Everything breaks down. And this will release all of the horrible enzymes that were inside the cell, including the lysosomal enzymes, the lactic acid, the lactate dehydrogenase with its gazillion subtypes. If this is a muscle, you have the carietin and kinase. you have the troponins, etc. And since we have tons of inflammation, expect TNF-alpha and the CRP to be elevated, also ESR, etc. But of course, for all of this to be elevated to the point to be detected by the lab, this has to be really bad necrosis and diffuse, not just one cell. If you want to learn more about neoplasia and the drugs used to treat cancer, check out my anti-cancer pharmacology course on my website medicosisperfectionist.com. Thousands of students have downloaded from my website before and I'm so grateful for you guys. Thank you for watching. Please subscribe, hit the bell and click on the join button. You can support me here or here. Go to my website to download my courses. Go to Picmonic for animated medical mnemonics. Thank you for watching. As always, be safe, stay happy, study hard. This is Medicosis. Perfectionality is where medicine makes perfect sense.