CH 5 Flashcards
Test 2
-Is the largest system of the body
-16% of body weight
-1.5 to 2 m2 in area
-is made up of two parts:
Cutaneous membrane (skin)
Accessory structures
Integument
Two Components of the Cutaneous Membrane
Outer epidermis
Inner dermis
Superficial epithelium (epithelial tissues)
Outer epidermis
Connective tissues
Inner dermis
Cardiovascular system
Blood vessels in the dermis
connections
Sensory receptors for pain, touch, and temperature
Nervous system
- Loose connective tissue
- Below the dermis
- Location of hypodermic injections
Hypodermis
- Protects underlying tissues and organs
- Excretes salts, water, and organic wastes (glands)
- Maintains body temperature (insulation and evaporation)
- Synthesizes vitamin D3
- Stores lipids
- Detects touch, pressure, pain, and temperature
Functions of Skin
- Is avascular stratified squamous epithelium
- Nutrients and oxygen diffuse from capillaries in the dermis
The Epidermis
- Contain large amounts of keratin
- Are the most abundant cells in the epidermis
Keratinocytes
- Covers most of the body
- Has four layers of keratinocytes
Thin Skin
- Covers the palms of the hands and soles of the feet
- Has five layers of keratinocytes
Thick skin
-The five strata of keratinocytes in thick skin
-From basal lamina to free surface
Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Structures of the Epidermis
- Is attached to basement membrane
- Forms a strong bond between epidermis and dermis
- Forms epidermal ridges (e.g., fingerprints)
Stratum Germinativum
- Increase the area of basement membrane
- Strengthen attachment between epidermis and dermis
- Has many basal cells or germinative cells
Dermal papillae
- Found in hairless skin
- Respond to touch (trigger nervous system)
Merkel cells
- Contain the pigment melanin
- Scattered throughout stratum germinitivum
Melanocytes
- Produced by division of stratum germanitivum
- Continue to divide, increasing thickness of epithelium
- Contain dendritic (Langerhans) cells, active in immune response
Stratum Spinosum — the “spiny layer”
Stops dividing, starts producing
Stratum Granulosum — the “grainy layer”
- A tough, fibrous protein
- Makes up hair and nails
Keratin
- Dense granules
- Cross-link keratin fibers
keratohyalin
- Produce protein fibers
- Dehydrate and die
- Create tightly interlocked layer of keratin surrounded by keratohyalin
Cells of Stratum Granulosum
- Found only in thick skin
- Covers stratum granulosum
Stratum Lucidum — the “clear layer”
- Exposed surface of skin
- 15 to 30 layers of keratinized cells
- Water resistant
- Shed and replaced every 2 weeks
Stratum Corneum — the “horn layer”
- The formation of a layer of dead, protective cells filled with keratin
- Occurs on all exposed skin surfaces except eyes
- Skin life cycle
- It takes 15–30 days for a cell to move from stratum basale to stratum corneum
Keratinization