Dermal is mainly composed of fibroblasts and their fibers and matrix, as well as blood vessels, lymphatic vessels, nerves, skin appendages and other cell components.
2. epidermis
The epidermis is located in the outermost layer of the skin, and it is keratinized stratified squamous epithelium, which is differentiated from ectoderm, from which skin appendages occur. Epidermis includes keratinocytes, melanocytes, Langerhans cells and Meckel cells.
3, subcutaneous tissue
Subcutaneous tissue is the loose connective tissue and adipose tissue under the skin, which connects the skin and muscles, and is usually called superficial fascia. Subcutaneous tissue is between skin and deep tissue, which makes skin have certain fluidity.
Extended data:
Function of epidermal layer
1, obstacle function
(1) The dense stratum corneum can cushion the external mechanical damage.
(2) The cells in the stratum corneum are closely arranged, and the stratum corneum contains less water, so the weak acidic environment on the skin surface can mechanically resist the invasion of microorganisms.
(3) Melanin secreted by non-keratinocyte melanocytes in epidermis can protect the skin from ultraviolet rays and play a role in photoprotection.
2. Absorption function
Skin is absorbed mainly in three ways:
(1) stratum corneum (main road)
(2) Hair follicles and sebaceous glands
(3) Porosity
Skin has the ability to absorb foreign substances, and it is also the physiological basis of transdermal absorption of topical drugs.
3. Immune function
Skin is not only the effector organ of immune response, but also has the function of actively participating in initiating and regulating skin-related immune response. Skin contains a variety of immune cell components and immune molecular components. Langerhans cells in epidermis are important immune cells, which can produce specific and nonspecific immune responses to invasive foreign substances.
References:
Epidermal —— Baidu Encyclopedia (the entry of popular science China certification)