in this video we'll be talking about different stages of wound healing so wound healing has different time kinetics different wound heals differently for example there are fast healing wound and there are slow healing wounds wounds in skin intestines connective tissue heals relatively faster because they contain stem cell which can easily replenish for these damage so high regenerative potential in contrast the wounds in muscle or let's say in nerve doesn't really heal very quickly and sometimes doesn't heal at all because of low regenerative potential so in this video we are going to focus on a superficial wound let's say let's say a skin wound due to a knife injury or other kind of damage and try to understand the steps of the wound healing process so first there would be hemostasis second inflammatory reactions three proliferation and remodeling all these four steps would be looked into details in this particular video so stay tuned till the end so let's begin with uh hemostasis imagine there is a skin uh damage here and it's quite a deep cut so the blood vessels underneath the skin would be ruptured and there would be blood coming out of the uh particular wound so after a point of time there would be veso constriction that means constriction of the blood vessels which would make it difficult for for blood to woo out from that region also there would be platlets that would adhere to the site of injury and they would attract more and more rbcs to try to form a blood clot eventually the platlet plug is formed followed by the fibin mesh so the fibrine mesh platlet plug all ensures that there is no more blood loss and this is the hemostasis phase that simply means like prevention of the external blood flow now meanwhile there are bacterias viruses Etc or pathogens who tried to invade through that breach in the skin so obviously body has to deploy immune cells to fight them one of the immune cells that are deployed first are these neutrophils neutrophils kind of engulf pathogens like bacteria they can also recognize the nature of pathogen using the toll receptor that they have and eventually macras are recruited macrophases are recruited second to the neutrophil so they take some time to come to the injury site so phagocytosis by the neutrophil is the first event then there are several inflammatory cyto such as interlukin 1 and six are actually secreted by macrofiles and nutrifil this attracts several other immune cell in the region of invasion just just that they can fight the infection better so neutr extravasation is the next step so the key events in this inflammation phase is phagocytosis and cyto secretion and fibroblast and endothelial Cell Activation so these inflammatory cyto can also activate fibroblast and endothelial cells in the near vicinity so overall in this in the step two of the inflammation it's also important to note that macras play a very important role they secrete substances that actually lead to angiogenesis that means formation of the new blood vessel so that is why we need to understand what are the substances that are secreted by these macras or other immune cells so one of the key factors are pdgf uh TGF beta Etc so here are few of the cell types that we are going to secrete some stuff that help in wound healing platlet secretes TGF beta and platlet derived growth factor all that leads to angiogenesis and fibrosis vascular Remodeling and smooth muscle migration is also triggered by these same factors then there are keratinocytes fibroblast macrophases M cells all of that secrete veg F or vascular endothelial growth factor so basically um that stimulates angiogenesis process fibroblast growth factor is secreted by fibroblast which helps in tissue Remodeling and metaloproteinases which are secreted by sometimes macrophases and other cell types can remodel the ECM and that is required for the end stage of the wound healing process the third step of the wound healing process is the proliferation phase at this phase angiogenesis would pick up and there would be several blood vessels which are forming underneath the injury side so more and more oxygen could be supplied to this particular region now basically there are granulation phase where Fibber blast proliferate and produce extracellular Matrix component such as collagen fibronectin proteoglycans Etc then ultimately there would be migration and proliferation of the epithelial cells nearby to close this wound you can see here there is reepithelialization which is happening and we can see that same event from a top view of the wound here there are new cells keratinocytes which are now migrating to close up the wound so after reepithelialization at the end of reepithelization the ECM remodeling happens so the ECM remodeling started at the end of proliferative phase now the ECM would be remodeled met metaloproteinases and metal protes inhibitor would sort of like remodel these uh extracellular Matrix in a meaningful way which is essential so proper ECM remodeling is essential for wound closure now there are different types of W closure for example there is primary intention healing in this case what happens is the wound edges are closely brought through let's say by sutures so it really form a clean uh cut it it it can be found in case of like surgical wounds there is secondary intention healing like wound ages are far apart and they cannot be basically uh bring in brought in together so the healing starts from the bottom and and ended in the up so it's kind of like a bottom up healing approach but it forms a distinct scar sometimes kid as well so that's pretty much it in this video we talked about different stages of wound healing if you like this video give it a quick thumbs up don't forget to like share and subscribe see you in next video e