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What layer of the skin is vascularized?
Only the dermis
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Keratinocytes
- Chief role is to produce keratin: the fibrous protein that helps give the epidermis its protective properties
- connected to one another by desmosomes
- arise in the deepest part of the epidermis (stratum basale)
- undergo continuous mitosis
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Melanocytes
- Synthesize the pigment melanin
- spider shaped epithelial cells
- found in the deepest layer of epidermis
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Merkel disc
functions as a sensory receptor for touch
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Langerhans cell
- Epidermal dendritic cell
- ingest foreign substances and are key activators of our immune system
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What are the layers of the skin?
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- Stratum Basale: single row of stem cells - a continually renewing cell population
- Stratum Spinosum: web like system of intermediate filaments, mainly tension resisting bundles of pre-keratin filaments
- Stratum Granulosum: consists of 3-5 cell layers in which keratinocytes appearance changes drastically and the process of keratinization begins
- Stratum Lucidum: Only in thick skin
- Stratum Corneum: outer most 20-30 layers; provides a durable overcoat
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What are the two layers of the dermis?
- Richly supplied with nerve fibers, blood vessels, and lymphatic vessels.
- Paillary: areolar connective tissue; friction ridges
- Reticular: 80% of the thickness of the dermis
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What are the three major skin markings?
- Friction ridges: increase friction and enhance the gripping ability of the fingers and feet
- Cleavage / tension lines: separations or less dense regions between bundles of connective tissue
- Flexure lines: dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures (deep creases in the palm).
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What three pigments contribute to skin color?
- Melanin: color ranges from yellow to tan to yellowish brown; found only in the deeper layers of the epidermis; freckles and moles are local accumulations of melanin
- Carotene: accumulates in the stratum corneium and in fatty tissue of the hypodermis; yellowish tinge of the skin
- Hemoglobin: pinkish hue of fair skin reflects the crimson color of the oxygenated pigment in RBC's.
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Sudoriferous glands
- Sweat glands
- Merocrine sweat glands with the secretory part coiled deep in the dermis
- Secretory cells are associated with myoepithelial cell's - specialized cells that contract when stimulated by the nervous system
- major role is to prevent overheating of the body
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Apocrine sweat glands
- merocrine glands that secrete their product by exocytosis
- Their ducts empty into hair follicles
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Ceremonious Glands
modified apocrine glands found in the lining of the external ear canal
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Sebaceous glands
- simple branched alveolar glands that are found all over the body except in the thick skin of the palms and soles
- Secrete sebum
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Vellus hair
body hair of children and and adult females
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Terminal hair
Coarser, longer hair of the eyebrows and scalp
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