Chp 5: Integumentary System Flashcards by Stephanie Bourque

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

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Layers of the Epidermis: deep to superficial

stratum basale
stratum spinosum
stratum granulosum
stratum lucidum (not present in thin skin) 
stratum corneum

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Epidermis

Keratinized stratified squamous epithelium consisting of 4 distinct cell types and 4 or 5 layers
Fast turn-over, resists damage, offers protection

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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)

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Melanocytes

Spider shaped epithelial cells found only in stratum basale

Synthesize melanin

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Langerhans cells

Star shaped dendritic cells arise from bone marrow, migrate to epidermis
ingest foreign substances and activate immune system

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Tactile Cells (Merkel Cells)

Present at epidermal-dermal junction (in stratum basale); shaped like spiky hemisphere

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Stratum basale

Deepest epidermal layer, aka stratum germinativum

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Stratum spinosum

“prickly layer”

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Stratum Granulosum

4-6 layers

Where process of keratinization begins

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Stratum Lucidum

In thick skin only
Thin translucent band just above stratum granulosum
2-3 rows of clear, flat, dead keratinocytes

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Stratum corneum (horny layer)

Outermost epidermal layer, 20-30 layers thick

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4 Major cell types of epidermis: Keratinocytes

Produce keratin, give epidermis protective properties

Present in every layer of epidermis

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4 Major cell types of epidermis: Melanocytes

Spider shaped cells that synthesize melanin

Found in deepest layer (stratum basale)

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4 Major cell types of epidermis: Dendritic cells (Langerhans cell)

Star shaped dendritic cell
Ingests foreign substances, activates immune system
Found in stratum spinosum

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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

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Thin Skin

Hairy, covers all body regions except palms and palmar surfaces of digits and soles
Fewer sudoiferous glands, sparser sensory receptors

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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