How Does a Cut Heal? Your Body's Repair Crew, Minute by Minute

How does a cut heal? Within seconds your vessels clamp down, and within minutes platelets and fibrin seal the gap. We follow wound healing from a paper cut's first sting to the scar, which tops out at about 80% of the skin's strength. Blood clotting runs on machinery we share with lampreys, then neutrophils and macrophages clean up and fibroblasts rebuild with collagen. Along the way: why a scab isn't new skin, why scar tissue is weaker than skin, and how spiny mice, axolotls and even human fetuses heal without a scar. 00:00 A hole in the wall 00:20 Your skin, and what lives on it 01:00 Second zero: the vessels clamp down 01:20 Platelets: cells that aren't cells 01:50 Grab, signal, pile up 02:20 Fibrin: the concrete 02:47 The clot pulls tight 03:06 Half a billion years of clotting 03:32 The alarm: a hydrogen peroxide trail 03:59 Redness, heat, swelling, pain 04:26 Hour one: neutrophils attack 04:54 Day one: the fallen 05:26 Days two to three: the big eaters 05:55 The scab is a roof 06:21 Day four: the builders 06:52 Weeks one to three: how strong is it? 07:22 The twist: it never gets all the way back 07:50 Who heals without a scar 08:21 Why settle for a patch? 08:56 Your body clock and healing 09:23 Behind the sting Sources: Rodrigues et al. 2019, Wound healing: a cellular perspective (Physiol Rev): https://pmc.ncbi.nlm.nih.gov/articles... Machlus & Italiano 2013, The incredible journey: from megakaryocyte development to platelet formation (J Cell Biol): https://pmc.ncbi.nlm.nih.gov/articles... MedlinePlus, Bleeding time: https://medlineplus.gov/ency/article/... Davidson, Tuddenham & McVey 2003, 450 million years of hemostasis (J Thromb Haemost): https://pubmed.ncbi.nlm.nih.gov/12871... Niethammer et al. 2009, A tissue-scale gradient of hydrogen peroxide mediates rapid wound detection in zebrafish (Nature): https://pmc.ncbi.nlm.nih.gov/articles... Brinkmann et al. 2004, Neutrophil extracellular traps kill bacteria (Science): https://pubmed.ncbi.nlm.nih.gov/15001... Leibovich & Ross 1975, The role of the macrophage in wound repair (Am J Pathol): https://pubmed.ncbi.nlm.nih.gov/1109560/ Almadani et al. 2021, Wound healing: a comprehensive review (Semin Plast Surg): https://pmc.ncbi.nlm.nih.gov/articles... Gonzalez et al. 2016, Wound healing: a literature review (An Bras Dermatol): https://pmc.ncbi.nlm.nih.gov/articles... Larson, Longaker & Lorenz 2010, Scarless fetal wound healing: a basic science review (Plast Reconstr Surg): https://pmc.ncbi.nlm.nih.gov/articles... Seifert et al. 2012, Skin shedding and tissue regeneration in African spiny mice (Nature): https://pubmed.ncbi.nlm.nih.gov/23018... Hoyle et al. 2017, Circadian actin dynamics drive rhythmic fibroblast mobilization during wound healing (Sci Transl Med): https://pubmed.ncbi.nlm.nih.gov/29118... Narration voice: Qwen3-TTS (synthetic). All animation, music and sound are original. This video explains physiology and is not medical advice. #woundhealing #skin #humanbody