Overview of the skin
1.Skin is the tissue on the surface of the body that is wrapped outside the muscles, and is the largest organ of the human body.
2.Skin is composed of epidermis, dermis, subcutaneous tissue, and contains skin appendages, abundant nerves, blood vessels, lymphatic vessels, muscles and fascia.
3.Adult skin body surface area is about 1.5-2m2.
4.The weight of the skin accounts for about 5%-16% of the total body weight.
The concept of inflammation
Inflammation is the body’s defense response to stimuli, manifested as redness, swelling, heat, pain, and dysfunction. Inflammation, which can be infectious inflammation caused by infection, or non-infectious inflammation not caused by infection. Usually, inflammation is beneficial and is the body’s automatic defense response, but sometimes, inflammation is also harmful, such as attacks on the body’s own tissues, inflammation in transparent tissues, etc.
Mechanisms of wound healing
Inflammation stage
1.The release of inflammatory mediators;
2.Increased vascular permeability and tissue edema;
3.The blood vessels are congested and dilated, causing redness and swelling;
4.The metabolism of tissue cells increases and the temperature rises;
5.Inflammatory mediators stimulate nerve endings to produce pain.
6.Thrombosis and complement response;
7.Infiltration of a large number of inflammatory cells.
8.The inflammatory period lasts for about 3-10 days.
9.In the inflammatory phase, a large amount of type III collagen is formed, and the most is produced in the 5-7 days of the inflammatory phase (depending on the degree of inflammation)
Proliferation stage
1.The proliferation stage is characterized by fibroblasts, endothelial cells, and keratinocytes migrating to the wound;
2.The proliferative phase occurs 10-14 days after exfoliative skin reconstruction, which is characterized by the proliferation of fibroblasts and the synthesis of collagen;
3.The proliferation of epidermis reaches its peak in 24-72 hours.
Remodeling stage
1.Keratinocytes rebuild the epidermis;
2.Endothelial cells rebuild blood vessels in inflammatory tissues;
3.Fibroblasts rebuild collagen (dermis) of inflammatory tissue;
4.The total amount of collagen in the wound reaches a peak in 2-3 weeks, but collagen remodeling can last for months or years.
Clinical manifestations of inflammation
1.Red: due to congestion and vasodilation of inflammatory lesions.
2.Swelling: due to exudate, especially inflammatory edema.
3.Heat: caused by capillary congestion and enhanced metabolism.
4.Pain: It is related to a variety of factors. Stimulation of inflammatory mediators, exudates in inflammatory lesions causing tissue edema, increased pressure, compression of nerve endings or traction on nerve endings can cause pain.
5.Dysfunction: For example, degeneration, necrosis of parenchymal cells in inflammatory lesions, mechanical obstruction and compression caused by inflammatory exudates with abnormal metabolic function can cause organ dysfunction.
Further reading：The principle and effect of cryolipolysis
