Post on 18-Dec-2015
What type of tissue you observe Friday?
Integumentary System
Integument: any covering or enclosure-Derma: skin
Dermatologist?
Stratified squamous epithelial cells
Components
• Skin • Accessory features:
– Sudoriferous glands (sweat glands)– Sebaceous glands (oil glands)– Hair– Nails
Skin accounts for how much of your body weight?
• Average = 15%, 8 pounds
What is the skin’s square footage?
• Covers up to 22 square feet (2 square meters) if all spread out
Did you know?
• As a fetus, you had webbed hands and feet
apoptosis
Function
• Protection– Cushioning, insulation, first defense
• Healing• Synthesizes vitamin D when exposed to UV• Sensory reception• Maintain homeostasis
– Temperature, Waste, water• Window into inner workings…examples:
– Jaundice, anemia, shock, etc
Where is the thinnest skin located?
• Eyelids• 0.01 to 0.015 cm thick
Where is the thickest skin found?
• Palms and heels• About 0.46 cm thick
Labeling
Two types of tissue
Epidermis• Moisture proof• Protective outer covering• Thin• Avascular• Outer layer = dead cells• Melanocytes – make
melanin• Constantly shedding
Dermis• Connective tissue• Makes up majority of the
skin• Provides support• Strength and suppleness• “true” skin – stays the same
throughout entire life
Epidermis and dermis of (a) thick skin and (b) thin skin(which one makes the difference?)
Epidermis: layers (on left) and cell types (on right)
Epidermis…
• Stratum germinativum• Cells die as move upwards• Stratum corneum• Cells undergo keratinization
– Tough protein– Deposited within a cell– Hardens and flattens the cells– Makes skin water-resistant
Dander
• Dead, sloughed off cells• When clump together = dandruff
How much skin will you lose over your lifetime?
• About 40 pounds of skin cells are shed
How often is your outer layer of skin “turned over”?
• monthly
Dermis
• Collagen + elastin in a gel-like substance• Strong and stretchable
Stretch marks: striae
• Dermal tearing• Extreme stretching of the skin
Blister
• Separation of epidermal and dermal layers by a fluid-filled pocket
Dermis…
• Also contains:– Blood and lymph vessels– Nerve endings– Hair follicles– Sweat and sebaceous glands– Collagen and elastin
tattoos
Subcutaneous Layer
• Not part of the skin = hypodermis• Loose connective tissue and adipose• Insulates from extreme temperature changes
in external environment• Anchors skin to underlying structure
– Some areas have no subcutaneous layer – connect directly to bone…
Subcutaneous injection
• Rich supply of blood vessels