13. Integumentary Sytem Flashcards
Integumentary consists of
Skin (epidermis and dermis)
Subcutaneous tissue (hypodermis)
Appendages (glands, hair, nails)
What is skin?
Largest organ of the body
Varies in thickness across body regions
Composed of 2 layers: epidermis and dermis
Holds a variety of appendages important for its function
Functions of skin
Protection
Temperature regulation
Excretion
Vitamin D production
Sensory reception
How does skin regulate temperature
Capillaries and sweat glands regulate heat loss
How does skin excrete waste
Excrete urea, salts, and water through sweat
How does skin produce vitamin D
Cells use UV radiation to synthesize vitamin D
Characteristics of the epidermis
Superficial layer of skin
Consists of keratinized stratified squamous epithelium
Primary cell type= keratinocytes
Dead cells rub off and are replaced
There are thick and thin skin
What are the surface cells of the epidermis
Dead keratinocytes full of protective protein, keratin
What are keratinocytes?
Produce keratin, primary cell type of epidermis
Number of layers of thick and thin skin
Thick: 5 layers ( hands & feet)
Thin: 4 layers
Layers of the epidermis
Stratum basale, stratum spinosum, stratum granulosum, stratum corneum, and stratum lucidum (only in thick skin)
Characteristics of stratum basale
Deepest layer, attached to dermis
Single row of stem cells undergoing mitosis
Includes tactile epithelial cells (Merkel cells) and melanocytes
What are tactile epithelial cells (Merkel cells)
Cells attached to nerve ending in stratum basale for touch sensation
What are melanocytes
Produce melanin and gives skin color
Absorbed by keratinocytes, protect from radiation
Characteristics of stratum spinosum
Several cell layers thick
Mitosis occurs but less that basal layer
Cells contain thick bundles of intermediate filaments with pre-keratin to resist tension
Include dendritic cells
What are dendritic cells?
Part of immune system for recognizing foreign proteins
Characteristics of stratum granulosum
1-5 flat cell layers
Cells contain pre-keratin and granules (i.e. granular layer)
Cells far from nutrients supplied by capillaries in dermis, organelles start to breakdown
What are granules
Help form keratin
Produce glycolipids to help prevent water loss