CAPS 390 Lecture 22: Lect_22_Skin_Summary
18 Nov 2015
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Lecture 22 oct. 24/2014 - skin/integument (roskelley) Largest organ in the body taking up to 15% of weight. Act as protective and waterproof layer. Contains sensory nerves to detect temperature, pain, pressure and touch. 2 layers: epidermis and dermis interdigitate via ridges/papillae formed by both. Epidermis: outer layer of stratified squamous keratinized epithelium made up of keratinocytes derived from the ectoderm. Gives rise to specialized skin appendages such as sweat, sebaceous glands and hair follicles (extends deep into dermis) Contains specialized cell types (melanocytes, merkel cells, langerhans cells) Dermis: underlying layer of dense irregular c. t. derived from mesoderm. Layers of epidermis: (from basal to apical) Undifferentiated highly mitotic stem cells. Cuboidal to low columnar epithelial cells/keratinocytes. When basal keratinocytes move up in to the next stratum they begin to differentiate. Langerhans cells, which are hematopoietic stem cell- derived antigen- presenting cells (apc"s. = dendritic cells); they migrate into the epidermis and primarily reside in the stratum spinosum.
