1.Name the tissue types composing the epidermis and dermis. List the major layers of each and describe the functions of each layer.
The epidermis is composed of keratinized stratified squamous epithelium tissue. The cells are specifically keratinocytes, melanocytes, Merkel cells, and Langerhans’ cells. The layers of the epidermis are the basal layer (stratum basale), it is the deepest layer and is attached to the dermis, the cells are actively mitotic. The next layer is the prickly layer (stratum spinosum), it is made of pre-keratin formed in thick bundles of intermediate filaments. The next layer up is the granular layer (stratum granulosum), here the cells are flattened and the organelles are deteriorating. Lastly is the horny layer (stratum corneum), it accounts for ¾ of the epidermal thickness. It is for waterproofing, protection from abrasion and penetration, and it renders the body relatively insensitive to biological, chemical, and physical assaults. In this layer, the cells are dead. The dermis contains strong, flexible connective tissue. The cell types include fibroblasts, macrophages, and occasionally mast cells and white blood cells. The papillary layer has areolar connective tissue with collagen and elastic fibers. Its surface contains peg-like projections called dermal papillae. The papillae contain capillary loops, Meissner’s corpuscles, and free nerve endings. The other layer of the dermis is the reticular layer. This layer accounts for 80% of the thickness of the skin. The collagen fibers add the strength and resiliency, while the elastin fibers provide stretch-recoil properties.
2. Compare the structure and locations of sweat and oil glands. Also compare the composition and function of their secretions.
The eccrine sweat glands are found in the palms of hands, soles of feet, and the forehead. The apocrine sweat glands are found in the axillary and anogenital areas. The ceruminous glands are modified apocrine glands in the external ear...
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