Intergument System Flashcards
What are the functions of Integument?
• Protection
- Protects against bumps and scrapes
- Keeps microorganisms out
- Prevents dehydration
- Protects against UV radiation from the sun
• Helps regulate body temperature
• Is involved with excretion of wastes through sweat
• Synthesizes vitamin D
• Is involved with sensory reception
- Sensory receptors tell us about the world around us
What are the epidermal cells?
Epidermal Cells
• Keratinocytes
• Melanocytes
• Tactile epithelial cells (Merkel cells)
• Dendritic cells
What are Keratinocytes?
Keratinocytes
• Most abundant
• Produce keratin
• Oldest cells are superficial, newest are deep
• Replaced every 35 to 45 days
What are Melanocytes?
Melanocytes
• Produce the pigment melanin
• Located in stratum basale
• Nearby keratinocytes consume melanin
What are Tactile epithelial cells (Merkel cells)?
Tactile epithelial cells (Merkel cells)
• Sensory touch receptors associated with
nerve ending
• Found in stratum basale only
What are Dendritic Cells?
Dendritic cells
• Part of the immune system
• Phagocytic
• Primarily in stratum spinosum
What are the Epidermal Layers?
Deepest
• Stratum basale
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum (only in thick skin)
• Stratum corneum
Most superficial
What are the properties of Stratum basale?
Stratum basale
• Deepest portion of epidermis, 1 layer
• High mitotic activity
• Mostly keratinocytes, some melanocytes and tactile epithelial cells
• Desmosomes hold cells together
What are the properties of Stratum spinosum?
Stratum spinosum
• Several layers of cells; some mitosis but not as much as st. basale
• “Spiny” looking cells caused by tissue preparation
• Some dendritic cells
What are the properties of Stratum granulosum?
Stratum granulosum
• 1 to 5 layers flattened keratinocytes
• Contain keratohyalin granules and lamellar granules (waterproofing)
What are the properties of Stratum lucidum?
Stratum lucidum (only in thick skin)
• Appears as a translucent band
What are the properties of Stratum corneum?
Stratum corneum
• Many layers thick
• Dead keratinocytes full of keratin
• Glycolipids add waterproofing
Thick vs Thin Skin?
Thick skin
• Has all 5 epithelial strata (stratum lucidum and thick
stratum corneum)
• Found in areas subject to pressure or friction
• Palms of hands, fingertips, soles of feet
Thin skin
• More flexible than thick skin; layers thin (no stratum
lucidum)
• Covers rest of body
• Hair grows here
What are callus, corns, and blisters?
Callus
• St. corneum thicker
Corn
• St. corneum thicker over bony prominence
Blister
• Small fluid-filled pocket b/w dermis and epidermis
What are Cleavage Lines?
Cleavage lines
• Offer strength to dermis in the direction of the collagen fibers
• Clinical significance:
- Incisions that run parallel to cleavage lines heal more readily than if made across
- Extensive stretching of dermis (as with pregnancy) can pull cleavage lines apart and cause striae (= stretch marks)
