Laurie SwezeyWoundeducators.com INC · CEO

Epidermis Layers | Layers of Skin | Wound Care Education

Name: Epidermis Layers | Layers of Skin | Wound Care Education
Uploaded: 2019-02-09T20:07:04+00:00
Duration: 2 min 19 s
Channel: Laurie Swezey
Description: The video provides an instructional overview of the epidermis, describing its overall thickness (0.06–0.6 mm) and the five distinct layers that reflect…

9 Feb 2019 · 2 min

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2:19

The video provides an instructional overview of the epidermis, describing its overall thickness (0.06–0.6 mm) and the five distinct layers that reflect stages of keratinocyte differentiation. It explains how new cells are generated in the deepest stratum basale, attached to the dermis via an acellular basement membrane that serves as scaffolding and a selective filter. The avascular epidermis receives nutrients by diffusion from the dermis. The narration proceeds through each layer—stratum basale, stratum spinosum (spiny keratinocytes), stratum granulosum (flattened cells with increasing keratin), stratum lucidum (thin, clear layer of dead cells found in thick skin of palms and soles), and the outermost stratum corneum (20‑30 dead keratinocyte layers that retain hydration and cause skin wrinkling in water). It also notes the variety of cell types present in the epidermis, emphasizing structural and functional aspects relevant to wound care education.

Chapters

The epidermis is the tough, leathery outer surface of the skin, ranging in thickness from 0.06 to 0.6 millimeters, with the thickest portions located in the palms of the hands and the soles of the feet. The epidermis is arranged in 5 layers that represent different stages of cellular differentiation. As new cells are formed, older cells elongate and their membranes thicken as they are pushed upward into the next epidermal layer. Let's explore these layers by clicking on the tabs to your left. The deepest layer, the stratum basale or basal layer, is attached to the dermis below by a thin acellular basement membrane. The basement membrane acts as scaffolding for the epidermis and as a selective filter for substances moving between the epidermis and the dermis. The epidermis is avascular. Receiving its blood supply through the diffusion of nutrients from the dermis across the semi-permeable basement membrane. The stratum spinosum is the next layer. It consists of several rows of more mature keratinocytes, which appear spiny under a microscope. Just above the stratum spinosum is the stratum granulosum. This layer contains 3 to 5 flattened cell rows with increasing concentrations of keratin. As the stratum lucidum is a thin, clear layer of dead skin cells in the epidermis and is named for its translucent appearance under a microscope. The stratum lucidum is found beneath the stratum corneum in areas where skin is thicker, such as the palms of the hands and soles of the feet. The outermost layer of the epidermis is called the stratum corneum, or horny layer. This layer consists entirely of dead keratinocytes. The stratum corneum can be 20 to 30 cells thick. The keratin in these cells helps keep the skin hydrated by preventing water evaporation. These cells can also absorb water, further aiding in hydration. This explains why you experience wrinkling of the skin when your fingers are immersed in water for long periods. There are a variety of cells located in the epidermis.