Ch. 5 Integumentary Flashcards
3 layers of skin
epidermis, dermis, subcutaneous (hypodermis)
Epidermis
- most superficial layer
- consists of epithelial tissue
- prevents water loss
- protects against abrasion and UV light
Cells of epidermis
keratinocytes and melanocytes
keratinocytes
- produce a protein mixture called keratin (makes cells more durable)
- all cells in all layers are these
melanocytes
contribute to skin color
keratinization
cells moving from the deeper epidermal layers to the surface and change shape and chemical composition
Epidermal strata
the many layers of cells in the epidermis (different regions)
Stratum basale (germinativum)
- single layer of cuboidal or columnar cells
- layer of epidermis that all cells arise from (basement membrane)
- attach to dermis by desmosomes
- mitosis happens, daughter cells get pushed upwards
Stratum spinosum
- consist of daughter cells from basale
- cells are still alive
- keratin fibers accumulate and are stockpiled
- lamellar bodies accumulate
Lamellar body (SS)
vesicles filled with triglycerides and other lipids
Stratum granulosum
- cells begin to flatten out and die
- lamellar bodies release lipids or fats and oils (cause the water proofing of skin)
Stratum lucidum
- not much difference between here and granulosum
- not present in all areas of the body
- cells are dead and appear transparent
Stratum corneum
- most superficial stratum of epidermis
- 2 to 3 dozens dead cells thick
- cells begin to shed due to non-working desmosomes
Keratohylin granules
- cross linking protein
- more of this, the tougher the cell
Thick skin
- has all 5 epithelial strata
- ie. palms of hands and soles of feet
Thin skin
- stratum lucidum is usually absent
- covers the rest of the body
Skin color
melanin, melanocytes, and melanosomes
Melanin
- the group of pigments primarily responsible for skin, hair, and eye color
- absorbs UV radiation (ie. tanning)
Melanocytes
- irregularly shaped cells that produce melanin
- does not produce new epidermal cells
- extend into the stratum spinosum