PNB 2265 Lecture Notes - Lecture 3: Mast Cell, Phagocytosis, Fibroblast
11 Sep 2017
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Learning objectives: describe the structure and function of skin. Structure of skin: epidermis = epithelial tissue: stratified squamous keratinizing epithelium to form a waterproof covering. Other cells include melanocytes (pigment melanin) and various immune and sensory cells: dermis = connective tissue. Epidermis structure: stratified squamous keratinizing epithelium, avascular: like all epithelial structures, the epidermis has no blood vessels, five layers in thick skin. Outermost layer = dead, keratinized cells: layers of epidermis. Stratum corneum: outermost/most superficial layer; dead flat keratin-filled cells. Stratum lucidum: dead cells, anucleate (no organelles at all); seen in thick skin. Stratum granulosum: granules (of keratin) visible in this layer; process of kertinization begins here. Stratum spinosum: almost all are amitotic (cannot divide;) are living cells connected by desmosomes. Stratum basale: regenerative layer; cells divide continuously. The dermis contains blood vessels, free nerve endings, oil and sweat glands (which derive from epidermis but are located in dermis. Two connective tissue layers: outer papillary layer.
