In the first period, the wound or injury is filled with a blood clot. A blood clot is a "biological dressing". It protects against excessive dehydration of the wound and intrusion of microorganisms into it.
A scab which may arise over a blood clot is a protective barrier
Under this barrier, the phagocytic cells (macrophages), which purify it from dead cells, pour into the wound. In the case of small wounds, the epidermis is completely regenerated while maintaining a layered skin pattern. When the wound is too deep or extensive, and the body is unable to rebuild all layers of the skin - a scar is created.
Dig. Cuteness and skin layers:
A - epidermis; B - dermis; C - subcutaneous tissue They can be damaged and bleed:
1. Cutaneous and vascular papillomas
2. The hook of the hair shaft
3. Sebaceous gland
4. Hair
5. Blood capillaries
6. Fat cells
7. Arteries and veins of the skin
8. Sweat glands
9. Hair follicle
10. Endings of nerve receptors
The healing process can be divided into three periods:
1. Self-healing of the blood vessels of the wound
2. Cleansing the wound
3. Reconstruction of damaged tissue and scar formation
Self-healing of the blood vessels of the wound
Injury that interrupts the vessels' continuity causes immediate contraction of the tissues and spasm of the blood vessels. In the vessels, a clotting process is created that forms a local plug from the platelets (thrombocytes) that squeezes the lumen of the vessel and blocks the flow of blood. Due to the activation of further enzymes responsible for blood coagulation, fibrinogen is polymerized. A gelatinous clot forms, gluing the edges of the wound.
Cleansing the wound
Inflammation is another important reaction to disrupting the continuity of skin tissues. It is initiated by the abundant secretion of tissue hormones from the prostaglandin group (prostacyclin, prostaglandin A, D and E). Within the wound, immune inflammatory cells accumulate - granulocytes and lymphocytes. Around the wound there is erythema, swelling, pain and locally elevated temperature. Inflammation widens local vessels, which facilitates the penetration of large immune cells in macrophages and fibroplasts (cells of connective tissue repair). Immune cells cleanse the wound from tissue debris, vascular clots and pathogenic bacteria. In clean wounds, with straight edges (in contrast to the so-called lacerated wounds) - the purification proceeds relatively quickly. This process usually takes 1-4 days. Wounds and cuts dirty, with irregular edges and tissue defects and containing so-called necrotic tissue cleanse itself free and with difficulty. First, the wound must be thoroughly washed and disinfected with germicidal agents. / 2 /
Wound reconstruction is phased:
- skin cells rebirth (proliferation)
- reconstruction of skin continuity (granulation and scarring),
Rebirth of skin cells
In this healing phase, the producer's skin cells become active - fibroblasts. These cells are the producers of collagen fibers - a product necessary for the construction and regeneration of connective tissue and for the reconstruction of damaged blood vessels. The cell regeneration phase of the manufacturing elements lasts from 4 to 42 days depending on the size of the wound. In small wounds and cuts, the reconstruction proceeds relatively quickly
Restoration of skin continuity
In small uninfected wounds and cuts, the edges of the wound stick together in the cleaning phase (or help them with special stitches). Relatively quickly, the continuity of the skin is reproduced, a linear scar is created. Reproduction of the skin's continuity in large wounds starts with the creation of a wound in the bottom of the wound or the so-called granules from fibroblasts built by blood vessels. This phase begins from the 1,2 or 3 weeks after the injury, and sometimes lasts for a very long time. Grain is a substrate for the regeneration of superficial layers of the skin and the epidermis, which grows from the wound edge to the granulation tissue. The newly formed collagen fibers, until now arranged chaotically within the wound, undergo the organization in a more regular structure. During the formation of the scar, type III collagen fibers are transformed into type I collagen, until the balance characteristic for healthy skin (collagen content I to III as 4: 1) is obtained. Already in the second week after the injury, the tissue gains 80% strength of healthy skin. However, early tissue necrosis or infection can disrupt and delay these processes.
