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