Skin
From Standard of Care
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| The dermis is connected to the epidermis through a basement membrane and is divided into two areas. a superficial area adjacent to the epidermis, called the papillary region, and a deep thicker area known as the reticular region. | The dermis is connected to the epidermis through a basement membrane and is divided into two areas. a superficial area adjacent to the epidermis, called the papillary region, and a deep thicker area known as the reticular region. | ||
| - | The hypodermis lies below the dermis, and is not part of the skin but attaches it to underlying bone and muscle, and supplies it with blood vessels and nerves. | + | The hypodermis, or subcutaneous tissue, lies below the dermis, and is not part of the skin but attaches it to underlying bone and muscle, and supplies it with blood vessels and nerves. |
| + | The hypodermis consists of loose connective tissue and elastin with fibroblasts, macrophages and adipocytes. | ||
| + | The hypodermis contains 50% of body fat serves as padding and insulation for the body. | ||
| + | Microorganisms colonize the skin surface. | ||
| - | 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. Another name for the hypodermis is the subcutaneous tissue. | + | As the skin ages, it becomes more fragile, dryer, thinner with fewer hair follicles,decreased sweat glands and more susceptible to microinjuries. |
| - | Microorganisms like Staphylococcus epidermidis colonize the skin surface. The density of skin flora depends on region of the skin. The disinfected skin surface gets recolonized from bacteria residing in the deeper areas of the hair follicle, gut and urogenital openings. | + | |
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| - | With aging the skin becomes more fragile, dryer, thinner with fewer hair follicles and decreased sweat glands. | + | |
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| - | Aging skin more susceptible to microinjuries which allow pathogens to penetrate. | + | |
Revision as of 02:45, 19 April 2012
Composed of two primary layers: the epidermis, and the dermis.
The epidermis is composed of the outermost layers of the skin, forming a protective barrier over the body's surface, responsible for keeping water in the body and preventing pathogens from entering, and is a stratified squamous epithelium, composed of proliferating basal and differentiated suprabasal keratinocytes.
Epidermis helps the skin regulate body temperature.
Keratinocytes are the major cells, constituting 95% of the epidermis.
Merkel cells, melanocytes and Langerhans cells are also present in the epidermis.
The skin can be further subdivided into the following strata or layers.
Stratum corneum
Stratum lucidum present in palms and soles
Stratum granulosum
Stratum spinosum
Stratum germinativum ( stratum basale)
Keratinocytes in the stratum basale proliferate through mitosis and the daughter cells move up the strata changing shape and composition as they undergo multiple stages of cell differentiation to eventually become anucleated.
Keratinocytes become organized, forming cellular junctions, known as desmosomes between cells and secreting keratin proteins and lipids which contribute to the formation of an extracellular matrix and provide mechanical strength to the skin.
Keratinocytes from the stratum corneum are shed from the surface by desquamation.
The epidermis contains no blood vessels.
Cells in the deepest layers of the skin are nourished by diffusion from blood capillaries extending to the upper layers of the dermis.
The epidermis and dermis are separated by the basement membrane that controls the traffic of cells and molecules between them.
The basement membrane also binds cytokines and growth factors, and serves as a reservoir for their release during remodeling or repair processes of the skin.
The dermis is the layer of skin beneath the epidermis consisting of connective tissue and cushions the body, provides tensile strength and elasticity to the skin.
The dermis contains nerve endings that provide the sense of touch and heat, hair follicles, sweat glands, sebaceous glands, apocrine glands, lymphatic vessels and blood vessels.
The blood vessels in the dermis provide nutrition and waste removal from the epidermis and dermis.
The dermis is connected to the epidermis through a basement membrane and is divided into two areas. a superficial area adjacent to the epidermis, called the papillary region, and a deep thicker area known as the reticular region.
The hypodermis, or subcutaneous tissue, lies below the dermis, and is not part of the skin but attaches it to underlying bone and muscle, and supplies it with blood vessels and nerves.
The hypodermis consists of loose connective tissue and elastin with fibroblasts, macrophages and adipocytes.
The hypodermis contains 50% of body fat serves as padding and insulation for the body.
Microorganisms colonize the skin surface.
As the skin ages, it becomes more fragile, dryer, thinner with fewer hair follicles,decreased sweat glands and more susceptible to microinjuries.
