In zootomy and dermatology, skin is an organ of the integumentary system made up of a layer of tissues that guard underlying muscles and organs. As the interface with the surroundings, it plays the most important role in protecting against pathogens. Its other main functions are insulation and temperature regulation, sensation and vitamin D and B synthesis.
Skin is composed of the epidermis and the dermis. Below these layers lies the hypodermis (subcutaneous adipose layer), which is not usually classified as a layer of skin.
The outermost epidermis consists of stratified squamous epithelium with an underlying basement membrane. It contains no blood vessels, and is nourished by diffusion from the dermis. The main type of cells which make up the epidermis are keratinocytes, with melanocytes and Langerhans cells also present. The epidermis can be further subdivided into the following strata (beginning with the outermost layer): corneum, lucidum, granulosum, spinosum, basale. Cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate, inducing expression of new types of keratin genes. They eventually reach the corneum and become sloughed off (desquamation). This process is called keratinization and takes place within about 30 days. This layer of skin is responsible for keeping water in the body and keeping other harmful chemicals and pathogens out.
Blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule. Arterial shunt vessels may bypass the network in ears, the nose and fingertips.
The dermis lies below the epidermis and contains a number of structures including blood vessels, nerves, hair follicles, smooth muscle, glands and lymphatic tissue. It consists of loose connective tissue otherwise called areolar connective tissue - collagen, elastin and reticular fibres are present. Erector muscles, attached between the hair papilla and epidermis, can contract, resulting in the hair fibre pulled upright and consequentially goose bumps. The main cell types are fibroblasts, adipocytes (fat storage) and macrophages. Sebaceous glands are exocrine glands which produce sebum, a mixture of lipids and waxy substances: lubrication, water-proofing, softening and antibactericidal actions are among the many functions of sebum. Sweat glands open up via a duct onto the skin by a pore.
The dermis can be split into the papillary and reticular layers. The papillary layer is outermost and extends into the dermis to supply it with vessels. It is composed of loosely arranged fibers. Papillary ridges make up the lines of the hands. The reticular layer is more dense and is continuous with the hypodermis. It contains the bulk of the structures (such as sweat glands). The reticular layer is composed of irregularly arranged fibres and resists stretching.
The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. The main cell types are fibroblasts, macrophages and adipocytes (the hypodermis contains 50% of body fat). Fat serves as padding and insulation for the body.
The tissue that makes up the skin is called the dermis and epidermis. The epidermis is the outside layer which is waterproof and serves as a protective covering for the inside tissue. The dermis is under the epidermis and contains things such as hair follicles, blood vessels and nerve endings.
Skin is differentiated into:
* Epidermis * Dermis and * Hypodermis # Epidermis: It is made up of stratified squamous epithelium in which keratiocytes, melanocytes, Langerhans cells and Merkel cells are seen. # Dermis: It mostly consists of connective tissues and contains blood vessels, sebaceous glands, sweat glands, hair follicles, apocrine glands and lymphatic vessels. # Hypodermis: is made up of adipose tissue.
Epithelial tissue and below the skin is Connective tissue
Epithelial Tissue
many. generally the outermost layer is stratified squamous epithelium.
epithelial
Skin is made up of epithelial tissue. stratified spuamous
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Epithelial.
Skin is an organ. It is not a tissue or tissue type.
Our skin is made up of collagen fibers.
The tissue in the epidermis is called epithelial tissue and the tissue in the dermis is largely connective tissue.
The type of epithelial tissue that is found in the epidermis of the skin is called stratified squamous epithelium. The dermis consists of connective tissue.
epithelial tissue
Connective tissue makes up the surface of the skin. This area is known as the apical surface, and the tissue is . epithelial.
Skin is made up of epithelial tissue. stratified spuamousnerves:)Epithelial.
In general, they are epithelial tissues which are in the skin and line body cavities.
The Epithelial Tissue.
epithelium tissue
nothing
Skin.
skin, cornea
Skin and mucous membranes