Bio 1145
Terms
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Define: dermatology, epidermis, dermis, hypodermis (subcutaneous).
Which layer is avascular?
Which layer is the thickest? -
Dermatology – study of hair skin and nails
Epidermis – above the dermis – outer most layer of cells in the skin helps form the cutis. Stratified squamous epithelium, composed of proliferating basal and differentiated suprabasal keratinocytes. It is avascular. 95% keratinocytes, the rest are melanocytes, Langerhans cells, Merkel cells and inflammatory cells.
Dermis – layer of skin with collagen, elastic fibers, connective tissue. Composed of fibroblasts, macrophages, adipocytes. Contains receptors for touch, sweat glands, apocrine glands, lymphatic and blood vessels - thickest
Subcutaneous/hypodermis – "beneath the skin",Mainly used for fat storage. Contains fibroblasts, adipose cells, macrophages -
Function of keratinocytes, melanocytes, langerhans cells, Merkel cells.
Keratinocytes make up __% of the cells. -
Keritinocytes – an epidermal cell that produces keratin 90 % of cells in epidermis.
Melanocytes – melanin producing cells in the bottom layer (stratum basale) of the skin’s epidermis.
Langerhans – are dendritic cells (antigen-presenting immune cells) of the skin and mucosa, and contain large granules called Birbeck granules. They are present in all layers of the epidermis, but are most prominent in the stratum spinosum. They also occur in the papillary dermis, particularly around blood vessels,as well as in the mucosa of the mouth, foreskin, and vagina. They can be found in other tissues, such as lymph nodes, particularly in association with the condition Langerhans cell histiocytosis (LCH).
Merkel Cell – are oval receptor cells found in the skin of vertebrates that have synaptic contacts with somatosensory afferents. They are associated with the sense of light touch discrimination of shapes and textures.
- Skin makes up _____% of weight of body.
- 15-20%
- 5 layers of the skin are?
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Stratum Basale (germinativum)
Stratum Spinosum (thorn like)
Stratum Granulosum (little grain)
Stratum Lucidum (clear)
Stratum Corneum - The palms, fingertips and soles have 5 layers in the epidermis – which layer do they include?
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Stratum Lucidum (clear)
Only in thick skin: fingertips, palms, soles.
3-5 layers of clear, dead keratinocytes. - How many layers per strata?
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Basale - Deepest layer
Spinosum - 8-10 layers
Granulosum - 3-5 layers
Lucidum - 3-5 layers
Corneum - 25-30 layers - Define Callus
- Callus - A localized thickening and enlargement of the horny layer of the skin.
- Define Corn
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Corn
A horny thickening of the skin, usually on or near a toe, resulting from pressure or friction.
Also called clavus. - Define Hyperkeratosis
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Hyperkeratosis
Hypertrophy of the cornea or the horny layer of the skin. - Define: Color changes of the skin.
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Dark skin - Large amt of melanin
Orange skin - Carotene
Albino - Can not make melanin
Cyanosis(blue) - Lack of oxygen
Jaundice(yellow) - Bilirubin accumulates in the skin
Ichymosis - Due to hematoma
Blushing - Increased blood flow to face
Fever or shock visible by color and temp of the skin - Define Striae
- Tears in the dermis due to increased size with pregnancy, growth spurt, obesity.
- Define how fingerprints and footprints are created.
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Epidermal ridges.
Developed during the third month of fetal development.
Created due to the pull of elastic fibers within the dermis.
Increases the surface area to grip with