2.0. Integumentary System Flashcards
Epidermis
- Superficial layer of epithelial tissue
- Avascular (nourished by diffusion from capillaries of the papillary layer of the dermis)
- Composed of epithelial cells arranged into layers or strata
- Separated from dermis by basement membrane
Dermis
- Deep layer connective tissue
- Structural strength
Subcutaneous Tissue
- Not part of skin
- Has adipose tissues
- Loose connective tissue that connects skin to underlying structures
Epidermal Cells Types
Keratinocytes
Melanocytes
Langerhans Cells
Merkel Cells
Keratinocytes
- Make up the majority of epidermal cells
- First layer of the epidermis contains the keratinocytes filled with proteins and has died
- Produce and fill themselves with keratin (a hard, waterproof protein) as they move toward the surface
Cornification
Stratum Corneum contains keratinocytes that have completely filled with keratin and died
Keratinization
Aas cells of the epidermis becomes filled with keratin and they move outward through the layers they fill with keratin
Melanocytes
- Produce skin pigments called MELANIN
- Cells stay in the stratum basale
- Keratinocytes take in melanin-filled vesicles called MELANOSOMES by endocytosis
- Melanocytes may not be evenly distributed across the skin, and denser patches of these cells account for freckles and moles
Langerhans Cells
Act as the outermost guard of the cutaneous system and likely to induce the first reaction against pathogens
Merkel Cells
Detect light, sense of touch, and superficial pressure.
Tactile Cells
- Receptors for fine touch
- Found in the stratum basale associated with nerve cells in the underlying dermis
Dendritic Cells
- Immune system cells found in the stratum spinosum and the stratum granulosum
- Alert the body’s immune system to the invasion of pathogens
Epidermal Stratum (deepest to superficial layer)
Stratum Basale (Germinativium) Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Cornelium
Stratum Basale (germinativium)
- Deepest portion of epidermis and single layer
- High mitotic activity and cells become keratinized
- Composed of continuously dividing cells
Stratum Spinosum
- Limited cell division
- Contain desmosomes, lamellar bodies, and additional keratin fibers
Lamellar Bodies
Lipid containing cells and provide the lamellar internal structure, contains enzymes, enzyme inhibitors, and antimicrobial peptides
Stratum Granulosum
Contains keratohyalin
Keratohyalin
Protein structure in the cytoplasmic granules of the keratinocytes of the epidermis
Stratum Lucidum
- Thin, clear zone
- Found only in palms and soles
LUCIDUM - clear
Stratum Corneum
- Most superficial and consists of cornified cells
- Thickest layer of the skin
- Contains the dead keratinized cells
Thick Skin
- Composed of 5 epithelial layers
- Found in areas subject to pressure or friction (palms of hands, fingertips, soles of feet, fingerprints and footprints
- Papillae of underlying dermis in parallel rows
Thin Skin
- Composed of 4 strata (no stratum lucidum since it can only be found in thick skin)
- More flexible than thick skin
- Covers rest of body
- Hair grows here
Callus
- Increase in the number of layers in the stratum corneum
- When this occurs over a bony prominence, a corn forms
Skin Color Factors
Pigments
Blood circulating through the skin
Thickness of stratum corneum