Lecture 25: Integument 1 Flashcards
List the epithelial layers of thick skin in the correct order:
Stratum basale (germinativum)-deepest Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum -superficial
Discriminate btw the 2 layers of the dermis and list characteristics of each layer.
Papillary layer: loose CT, separated from epidermis by basal lamina. Network of fine elastic fibers and abundant capillaries.
Reticular layer: dense irregular CT. Includes fibrocytes, macrophages, and adipocytes.
List characteristics of the hypodermis
Loose CT underlying dermis.
Corresponds to superficial fascia of gross anatomy.
Technically not part of the skin.
May contain fat cells that can form a thick layer called panniculus adiposus.
Identify each layer of thick skin epidermis and dermis from photomicrographs.
Stratum lucidum is only in THICK skin
Dermis: papillary and reticular layer
Compare thick skin to thin skin.
Thick skin: occurs on palms. ALL 5 layers.
Thin: rest of body. Thinnest on eyelids. Thickest is on back. Thinner on flexor than extensors. LACKING STRATUM LUCIDUM
Explain how ridges are created in the skin to form the basis for fingerprinting.
Primary dermal ridge: r/t fingerprinting. Formed 3rd to 4th mon of life. Subdivided into 2 secondary dermal ridges by interpapillary peg (downward growth of epidermis along crest)
Secondary occurs in double rows and branched.
Describe the process of keratinization
Simple cuboidal nucleated cells that begin to divide and lose nuclei. Leaving only keratin in cell.
List the characteristics and functions of langerhans cells, merkel cells, and melanocytes.
Langerhans cells= dendritic cells From monocytes, Antigen-presenting cells, Primarily in stratum spinosum, Migrate from epidermis to lymph nodes, Birbeck granules
Meckel’s cells= mechanoreceptors, may also act as diffuse neuroendocrine cells, usually in stratum germinativum, contain catecholamine-like granules
Melanocytes: from melanoblasts, dont form desmosome attachments in epidermis, inject melanin granules into keratinocytes.
list major characteristics of each layer of epidermis:
Stratum basale (germinativum): columnar high cuboidal keratinocytes. Keratin 5 and 14. Single layer of cells. High mitotic activty.
Stratum spinosum: polyhedral shaped cells (prickle). Keratins 1 and 10. Keratohyalin granules develop. Membrane-coating granules 1st appear. Tonofibrils.
Stratum granulosum: multilayered. Keratins 2e and 9. Flattened nucleated keratinocytes. Keratohyalin aggregates, lamellar bodies. Tonofilaments.
Stratum lucidum: flat keratinocytes w/o nuclei/organelles. Only in thick skin. Contains eleiden
Stratum corneum: multilayer, thicker in thick skin, enucleated, flattened, dead keratinocytes. Cytoplasm replaced w/ keratin.
Explain the embryonic origins of the epidermis and dermis.
Epidermis starts as a single layer of ectodermal.- divide during the 6th week to form.
Dermis is derived from mesoderm.