Integumentary System Flashcards
2 parts of the integumentary system.
Cutaneous membrane(skin) and accessory structures.
2 parts of cutaneous membrane
Outer epidermis (epithelial tissues) and inner dermis (connective tissues)
Relationship between the subcutaneous layer and cutaneous membrane.
Subcutaneous layer(superficial fascia or hypodermics) loose connective tissue, below the dermis, location of hypodermic injections.
Functions of the skin
Protects underlying tissues and organs; excretes salt, water, and organic wastes(glands); thermoregulation(maintains body temp w/ insulation and evaporation); synthesizes vitamin d; stores lipids; detects touch,pressure,pain,and temp; non verbal communication.
Characteristics of the epidermis
Avascular stratified squamous epithelium
Nutrients and oxygen diffuse from capillaries in the dermis
Multilayered flexible self repairing barrier
Prevents fluid loss
Protects from UV radiation
Produces vitamin D
Resists abrasion, chemicals, and pathogens
Keratinocytes
Most abundant epidermal cells
Produce keratin
Tightly connected by desmosomes
Thick skin
Covers palms of hands and soles of feets
5 layers of keratinocytes
Layers of epidermis
From outside to inside Stratum Corneum Stratum Lucidum(only in thick skin) Stratum Granulosum(cells start to die here) Stratum Spinosum Stratum Basale
Thin skin
Covers most of body
Has only 4 layers
No stratum lucidium
Stratum Basale
Germinative layer
Single layer of cells
Has many stem(germinative) cells and young keratinocytes resting on basement membrane
Has melanocytes (10-25%)
Attached to basal lamina by hemidesmosomes
Forms strong bond between epidermis and dermis
Stratum Corneum
Horny layer
Exposed surface of skin
Up to 30 years of dead scaly keratinized cells
Keratinization
Formation of a layer of dead protective cells filled with keratin
Occurs on all exposed skin surfaces except eyes
Dehydration
Water loss through skin
Results from:
From damage to stratum Corneum (burns and blisters; insensible perspiration)
From immersion in hypertonic solution (seawater;osmosis)
Hydration
Results from immersion in hypotonic solution (bath water) or osmosis
Keratin of stratum Corneum absorbs water and swells
Causes stretching and wrinkling of skin
Skin color
Depends on melanin
Also carotene and hemoglobin (red blood cells)
Based on quantity of melanin and color of melanin.
Not number of melanocytes
Melanin
Yellow brown or black pigment
Produced by melanocytes in stratum Basale
Surrounding keratinocytes pick up melanin as it is produced
Dark skin
More melanin production, melanin granules more spread out and melanin breaks down more slowly
Light skin
Melanin clumps near nucleus (less color
Imparted on cells)
Breaks down more rapidly
Not seen beyond stratum Basale