Chp 5: Integumentary System Flashcards
Functions of Integumentary System
- Protection of internal organs from physical, chemical and microbial agents
- Body temperature regulation
- Synthesis of Vit D
- Cutaneous sensation: Helps body sense changes in environment (and respond)
- Blood reservoir
- Excretion of nitrogen containing wastes, water, and salt
Layers of the Epidermis: deep to superficial
stratum basale stratum spinosum stratum granulosum stratum lucidum (not present in thin skin) stratum corneum
Epidermis
Keratinized stratified squamous epithelium consisting of 4 distinct cell types and 4 or 5 layers
Fast turn-over, resists damage, offers protection
Keratinocytes
Produce keratin (fibrous protein) By the time they reach the skin surface, they are dead, scale-like structures. Millions rub off every day, new epidermis every 25-45 days. Persistent friction causes thickening of epidermis (callus)
Melanocytes
Spider shaped epithelial cells found only in stratum basale
Synthesize melanin
Langerhans cells
Star shaped dendritic cells arise from bone marrow, migrate to epidermis
ingest foreign substances and activate immune system
Tactile Cells (Merkel Cells)
Present at epidermal-dermal junction (in stratum basale); shaped like spiky hemisphere
Stratum basale
Deepest epidermal layer, aka stratum germinativum
Stratum spinosum
“prickly layer”
Stratum Granulosum
4-6 layers
Where process of keratinization begins
Stratum Lucidum
In thick skin only
Thin translucent band just above stratum granulosum
2-3 rows of clear, flat, dead keratinocytes
Stratum corneum (horny layer)
Outermost epidermal layer, 20-30 layers thick
4 Major cell types of epidermis: Keratinocytes
Produce keratin, give epidermis protective properties
Present in every layer of epidermis
4 Major cell types of epidermis: Melanocytes
Spider shaped cells that synthesize melanin
Found in deepest layer (stratum basale)
4 Major cell types of epidermis: Dendritic cells (Langerhans cell)
Star shaped dendritic cell
Ingests foreign substances, activates immune system
Found in stratum spinosum
4 Major cell types of epidermis: Merkel Cells (tactile cells)
Shaped like spiky hemisphere
Works with disclike sensory nerve ending to function as touch receptor
Thin Skin
Hairy, covers all body regions except palms and palmar surfaces of digits and soles
Fewer sudoiferous glands, sparser sensory receptors
Thick skin
Hairless, covers palms, palmar surfaces of digits, soles
Has stratum lucidum: layer below stratum corneum and above stratum granulosum; 2-3 rows of clear, dead keratinocytes
No hair, no sebaceous glands
More sudoiferous glands, denser sensory receptors
Melanin
yellow to reddish brown to black pigment
Freckles and moles - local accumulations of melanin
Carotene
Yellow to orange pigment
Most obvious in palms/soles of feet
Precursor to Vit A
Hemoglobin
red, 02 carrying pigment in blood cells
Vitiligo
Chronic autoimmune disorder, depigmentation of skin
Albinism
Congenital disorder; partial/complete absence of pigment in skin, hair, eyes
Fingerprints
Epidermis projecting into dermis between dermal papillae
Increases surface area and grip of hands and feet
Dermis
strong, flexible connective tissue
Rich supply of nerve fibers, blood vessels, lymphatic vessels
Dermis: papillary layer
Thin superficial layer of areolar connective tissue
Dermal papillae: peglike projections into epidermis; some contain capillary loops, others house pain receptors and Meissner’s corpuscles (touch receptors)
Dermis: reticular layer
80% of dermis
irregularly arranged, dense fibrous CT
Provides temperature stability, prevents dehydration
Cleavage Lines
Separations between bundles of collagen fibers; Incisions made parallel to cleavage lines heal more readily
Hypodermis
Subcutaneous tissue just deep to skin
aka superficial fascia
Stores fat, anchors skin to underlying structures
Shock absorber, insulator
Hair
pili, flexible strands produced by hair follicles, consist largely of dead, keratinized cells
Medulla: central core, large cells and air spaces
Cortex: bulky layer surrounding medulla
Cuticle: single layer of cells
Eccrine sweat glands
Most common (palms, forehead, soles) watery secretion, cools body
Apocrine
Axilla, groin, bearded region of male
Body odor: bacteria metabolize secretion
Stimulated when frightened, during pain/emotional upset
Ceruminous glands
Earwax (cerumen)
Mammary glands
specialized sweat glands that secrete milk
Hair follicle
tube-like pocket that protects root
Hair root
Part located below surface of scalp
Hair shaft
portion of hair that projects above skin
Hair bulb
Lowest part of hair strand, fits over papilla
Arrector pili muscle
tiny, involuntary muscle, causes goose bumps
Nails
Tightly packed, hard keratinized epidermal cells
Rule of 9
Anterior and posterior head and neck = 9% Anterior and posterior upper limbs = 18% Anterior and posterior trunk = 36% Perineum= 1% Anterior and posterior lower limbs = 36%
First degree burn
epidermis only, redness
Second degree burn
Epidermis and dermis, with blistering
Third degree burn
full thickness, destroying epidermis, dermis, often part of hypodermis
