Lecture 7 Lecture Outline:I Integumentary systema. Dermis histologyb. Subcutaneous layer (hypodermis)II Skin cancer a. Basal cell carcinomab. Squamous cell carcinomac. Malignant melanomaIII Burnsa. First, second, third degreeHistology of Skin:- Epidermis: keratinized stratified squamosal epithelium- Dermis: second layer of skin, composed of two layerso Papillary layer: consists of areolar connective tissue Lots of blood vessels Dermal papillae: increase surface area between epidermis and dermis to hold together bettero Reticular layer: makes up most of the dermis Composed of mainly collagen fibers with elastic fibers Dense irregular connective tissue (leather) Lines of cleavage: Most collagen and elastic fibers in any location of dermis arranged in parallel- Orientation depends on stress placed on skin during normal movement- A cut parallel to line of cleavage usually remains closed- A cut at right angle will be pulled open as cut elastic fibers recoilo Contains blood vessels, lymphatic ducts, sensory receptorso Contains hair follicles and accompanying sebaceous glands Arrector pili muscle: band of smooth muscle , responsible for goose bumps- Subcutaneous layer (hypodermis): contains larger blood vessels, adipose tissueo Good injection site because no vital organsCancer: a particular cell type undergoes uncontrolled cell multiplication and growth- Can be described aso Malignant: has ability to metastasize/move to other parts of the bodyo Benign: does not spread to distant locationso Primary: cancer originated in the spot of the body that it currently iso Secondary: cancer that originated in another location of the body and metastasized to its current location- Skin Cancer: induced by ultraviolet rays of the sun, UVA and UVB rays are both harmfulo Most prevalent of all cancers (1 out of 5 Americans)o Incidence has increased by 800% in last 50 yearso Everyone is at risk but fair skinned individuals most at risk (blondes & redheads)o 3 main types named for cell sin epidermis that they arise fromBio 312 Basal cell carcinoma: most common type but the least malignant- Arises from cells in stratum basale, eventually invades dermis- Lesion first appears as small shiny bump, later develops central ulcer- Surgical removal (99% cure) Squamous cell carcinoma: arises from keratinocytes in stratum spinosum- Appears as raised, reddened, scaly bumps- Later forms a concave ulcer with raised edges- Cure rate high if detected and treated early, otherwise can metastasize to lymph nodes Malignant melanoma: arises from melanocytes- Most deadly because it metastasizes quickly and resistant to chemotherapy- Early detection is the key to survival,- ABCDE rule: asymmetry, Border irregularity, Color, Diameter, ElevatedBurns: a leading cause of accidental death- Urgent considerations in treatment are fluid replacement (can lose up to 75% of plasma within a few house), infectioncontrol, administration of excess calories to replace lost proteins and precursors for tissure repair- Classified by the depth of the burn:o First degree burns: involves epidermis only, heal in a few days, rarely leaves scars (sun burn)o Second degree burns: involves part of dermis, may take weeks to months to heal, probably leave scarso Third degree burns: all layers of skin and often deeper tissues, often require skin grafts, area is often left painless because of the destroyed sensory
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