Transcript "Skin" ppt notes

Skin and the
Integumentary
System
Skin and the Integumentary
System
• Composed of several tissues
• Maintains homeostasis
• Protective covering
• Retards water loss
• Regulates body temperature
• Houses sensory receptors
• Contains immune system cells
• Synthesizes chemicals
• Excretes small amounts of waste
Layers of Skin
1. Epidermis
2. Dermis
3. Subcutaneous layer
Epidermis
• lacks blood vessels
• keratinized
• thickest on palms and soles (0.8-1.4mm)
• melanocytes provide melanin
• rests on basement membrane
• stratified squamous
Epidermis (cont.)
Layers of Epidermis
• stratum corneum
• stratum lucidum
• stratum granulosum
• stratum spinosum
• stratum basale
Dermis
• on average 1.0-2.0mm thick
• binds epidermis to underlying
tissues
• irregular dense connective tissue
• muscle cells
• nerve cell processes
• blood vessels
• hair follicles
• glands
Subcutaneous Layer
• hypodermis
• loose connective tissue
• adipose tissue
• insulates
• major blood vessels
Hair Follicles
• epidermal cells
• tube-like depression
• extends into dermis
• hair shaft
• hair root
• hair papilla
• dead epidermal cells
• melanin
• arrector pili muscle
Nails
• protective coverings
• composed of: nail plate,
nail bed and lunula
Sebaceous Glands
• usually associated with hair
follicles
• holocrine glands (secrete
entire cell)
• secrete sebum (fatty
material + cellular debris)
• absent on palms and soles
Sweat Glands
• or sudoriferous glands
• widespread in skin
• deeper dermis or hypodermis
• eccrine glands (or merocrine,
forehead, neck and back)
• apocrine glands (axillary
region, groin, around nipples)
• OTHER GLANDS:
ceruminous glands (external
ear canal) AND mammary
glands (milk)
Problems in Temperature
Regulation
Hyperthermia – abnormally high body temperature
Hypothermia – abnormally low body temperature
Skin Color
Genetic Factors
Physiological Factors
• varying amounts of
• dilation of dermal blood
melanin
vessels
• varying size of melanin
• constriction of dermal blood
granules (darker
vessels
skin, larger granules)
• carotene (yellow pigment in
• albinos lack melanin
yellow vegetables)
• jaundice (liver malfunction)
Environmental Factors
• sunlight
• UV light from sunlamps
• X rays
Healing of Burns
• First degree burn – superficial partialthickness (injures only epidermis). Skin will
be red, swollen, painful and sensitive to
touch. Usually heals in 1-2 days. Mild
sunburn is a common 1st degree burn.
• Second degree burn – deep partial-thickness
(some epidermis and some dermis). Skin
will be painful, swollen, red, and blistered
or oozing fluid.
Healing of Burns (cont.)
• Third degree burn – full-thickness (destroys
epidermis, dermis and accessory organs of skin)
• autograft (from own body)
• homograft (from cadaver)
• various skin substitutes (amniotic tissue, lab skin)
• extensive scars
• The skin will be black, white, and charred.
• There is less pain because the nerves have been
destroyed.
• Fourth Degree Burn: extends through entire
skin, and into underlying fat, muscle and bone.
• requires excision (amputation, significant
functional impairment and, in some cases,
death)
• painless (nerves have been destroyed)
FIRST
DEGREE
BURN
2ND
DEGREE
BURN
(SUPERFICIAL
PARTIAL
TICKNESS)
2ND DEGREE
BURN
(DEEP PARTIAL
TICKNESS)
3RD
DEGREE
BURN
(FULL
THICKNESS)
4TH
DEGREE
BURN
Rule of Nines
Life Span Changes
• Scaly skin
• Age spots
• Dermis becomes reduced
• Loss of fat
• Wrinkles
• Sagging
• Sebaceous glands secrete
less oil
• Melanin production slows
• Hair thins
• Number of hair follicles
decrease
• Impaired nail growth
• Sensory receptors decline
• Inability to control body
temperature
• Less vitamin D production
Clinical Application
Acne Vulgaris
• most common skin disorder
• sebum and epithelial cells clog glands
• produces whiteheads and blackheads
• anaerobic bacteria trigger inflammation (pimple)
• largely hormonally induced
• androgens stimulate sebum production
• treatments include antibiotics and topical creams