It is an organ wrapped on the body surface and directly contacted with the external environment. It can protect, excrete, regulate body temperature and feel external stimuli. It is the largest organ in human body organs
Chinese name
skin
Foreign name
skin
Structure
Epidermis, dermis, subcutaneous tissue and skin appendages[1]
Skin is divided into epidermis andgenuine leatherTwo layers. The epidermis is on the surface of the skin and can be divided into two parts: the cuticle and the germinal layer.The keratinized cells form the stratum corneum, which becomes dander after falling off.Germinal layerThe cells divide continuously and can supplement the exfoliated cuticle.There are melanocytes in the germinal layer, and the melanin produced can prevent ultraviolet rays from damaging internal tissues.The epidermis is a stratified flat epithelium, while the dermis is a dense connective tissue with many elastic fibers and collagen fibers, so it is elastic and resilient.The dermis is thicker than the epidermis and has abundant blood vessels and nerves.There is subcutaneous tissue under the skin, which is loose connective tissue with a large amount ofFatCells.The skin also has hair, sweat glands, sebaceous glands, finger (toe) nails and many other appendages.
Anatomical interpretation
Announce
edit
It refers to the tissue that covers the surface of the human body and contacts with the external environment directly.It has the functions of protection, sensation, secretion, excretion and respiration.It is closely combined by epidermis and dermis. ①epidermis.It is composed of multiple layers of flat epithelium, and from shallow to deep, it is the stratum corneum, stratum pellucidum, stratum granulosus and stratum germinatum.The stratum corneum is composed of multiple layers of keratinized epithelial cells (the nucleus and organelles disappear, and the cell membrane is thick). It is lifeless and impermeable, and has the functions of preventing the outflow of tissue fluid, anti friction and anti infection.The cells in the germinal layer continuously proliferate and gradually move outward to supplement the constantly falling cuticle.The germinal layer contains a kind of melanocytes, which can produce melanin.The color of skin is related to the amount of melanin. ②The dermis, composed of dense connective tissue, is the papillary layer and the reticular layer from shallow to deep, and there is no obvious boundary between the two layers.The thickness of dermis is about 0.07~0.12 mm;The dermis of palm and foot is thicker, about 1.4 mm;Eyelid and tympanic membrane are thin, about 0.05 mm.The papillary layer is connected with the germinal layer of the epidermis, where there are abundant receptors such as capillaries, lymphatic vessels, nerve endings and tactile corpuscles.The reticular layer is connected with the subcutaneous tissue, which is rich in collagen fibers, elastic fibers and reticular fibers.They interweave into a net to make the skin more elastic and resilient.There are also abundant blood vessels, lymphatic vessels and nerve endings in the reticular layer.
The skin covers the whole body surface and is the largest organ of the human body, accounting for about 16% of the body weight.The adult skin area is about 1.2-2.0 square meters.The thickness of skin varies throughout the body, with the thickest at the back, neck, palm and sole, and the thinnest at the armpit and face, with an average thickness of 0.5-4.0 mm.Although the thickness of skin varies from place to place, it can be divided into two layers: epidermis and dermis, and connected with deep tissue by subcutaneous tissue.The color of skin varies according to race, age and health status.There are very dense concave grooves in various directions on the skin, which are called skin grooves.The rhomboid or polygonal ridges between the skin grooves are skin ridges, which form fingerprints in the finger pulp.Fingerprint shapes are different among individuals, so fingerprints have individual differences.There are hairs of different lengths and thicknesses on the skin.There are nails and toenails at the ends of the limbs.The skin can secrete sweat and sebum, which are secreted by sweat glands and sebaceous glands.
