BIO 210 Chapter 5 Already Graded A

BIO 210 Chapter 5 Already Graded A epidermis superficial region of skin composed of epithelial cells dermis middle region of skin composed mainly of fibrous connective tissue (fibroblasts) and occasionally mast cells as well as white blood cells hypodermis subcutaneous layer deep to skin composed mainly of adipose tissue, not technically part of the skin keratinocytes cells in epidermis that produce fibrous protein keratin; dead at the surface and held together by desmosomes when alive melanocytes cells deep in epidermis that produce pigment melanin and protect nucleus of keratinocytes from UV radiation dendritic (langerhans) cells in epidermis that are macrophages and help activate immune system by presenting antigens to immune system cells tactile (merkel) cells in epidermis that are touch receptors and the only type of touch receptors in epidermis basale, spinosum, granulosum, lucidum and corneum strata of epidermis from basement membrane to apical surface stratum basale stratum with single row of stem cells and deepest epidermal layer, contains melanocytes stratum spinosum stratum with cells and web-like system of intermediate pre keratin filaments attached to desmosomes with abundant melanin granules and dendritic (langerhan) cells stratum granulosum stratum with three to five cell layers of flattened cells with cytoplasm that contains granules of keratohyaline and lamellate granules keratohyaline forms keratin in superficial layers of epidermis lamellate granules exocytosed to form lamellate layers in interstitial spaces and a type of glycolipid stratum lucidum stratum present in thick skin only and compromised of a few rows of flat, dead keratinocytes (thin, transparent band) stratum corneum stratum with layers of dead, flat keratinized cells and interstitial spaces filled with lamellate layers cementing them together, results in most of protective features attributed to integumentary system papillary (upper) and reticular (deeper) two layers of dermis papillary layer layer of dermis connected to epidermis and composed of areolar connective tissue with collagen and elastic fibers and