What type of tissue you observe Friday Integumentary
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 Dermis Moisture proof Protective outer covering Thin Avascular Outer layer = dead cells Melanocytes – make melanin • Constantly shedding • 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
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