Modified from:

1
Modified from

• Powerpoint Presentation for BG210 made by
• Dr. Nora Espinoza, Ph. D.
• Which was

2
Modified from a PowerPoint Presentation made
to accompanyHoles Human Anatomy and
Physiology, 11/e byShier,
Butler, and LewisMcGraw-Hill - publisher
3
Integumentary system

• Al Mina, M.D.
• Erskine College

4
Skin

• Largest organ
• Provides protection
• Aids in temperature regulation
• Sensation
• Synthesis of important compounds
• Immunity
• Excretion

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Composition

• Epidermis - epithelium
• Dermis
• Multiple connective/other tissue types
• Separated by basement membrane
• Lays on top of subcutaneous tissue (hypodermis
  not part of skin)

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Cutaneous Membrane
Figure 6.2
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Epidermis

• Stratified squamous epithelium
• No blood vessels
• Composed of layers (strata)
• Innermost stratum basale primarily cell
  division
• Cells move to outer layers, become flattened,
  keratinized

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Epithelial cell layers

• Stratum basale
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum (clear cells)
• Stratum corneum
• Dead, non-nucleated cells that are keratinized

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Figure 6.3
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Contd

• Epidermis thickness varies based on location
• Palms and soles 0.8-1.4 mm
• Other areas average 0.1 mm
• Cell division keeps pace with destruction,
  increases in high pressure areas (calluses)

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Melanocytes

• Found in stratum basale and dermis
• Produces melanin which helps determine skin color
• Protects (somewhat) from sun exposure
• May transfer some pigment to epidermal cells

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Melanin
Figure 6.4
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Figure 6.5
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Bad stuff
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Pressure

• Inhibits blood flow
• Can lead to damage/ulcerations
• Immobile patients at high risk

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Cell growth

• Increased keratinization - psoriasis

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Sunburn

• Inflammation of cells
• Causes significant damage
• UV rays damage DNA, which body can repair, but
  over time leads to increased risk of

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Skin cancer

• Cells begin to divide abnormally, quickly, dont
  function properly.
• Melanoma worst
• Incidence of skin cancer increasing over past 20
  years

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Dermis

• Connects epidermis to surrounding tissue
• Irregular border forms dermal papillae
• fingerprints

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Figure 6.3
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Composition

• Thickness from 0.5-3 mm
• Irreg. dense connective tissue network of
  fibers
• Smooth muscle follicles and glands
• Skeletal muscle facial expression
• Nerve cell processes
• Sensors

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Contd

• Blood
• Hair
• Sebaceous glands
• Sweat glands

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sensors

• Pacinian corpuscles pressure
• Meissners corpuscles light touch
• Temperature
• pain

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Accessory structures
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Hair follicles

• Present on most skin surfaces
• Depression of epidermal cells
• Cells divide at base (hair papilla)
• Push up and die, form hair

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Hair contd

• Pigment determines color
• Smooth muscle (arrector pili) attached to each
  follicle

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Cutaneous Membrane
Figure 6.2
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Nails

• Nail plate overlying nail bed
• Grows most actively at base
• Keratinized cells push outward

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Sebaceous glands

• Often associated with hair follicles
• Holocrine glands that produce sebum
• Softens, waterproofs skin
• Exess causes acne

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Sweat glands

• Coiled tube that extends to surface
• Lined with epithelial cells
• Most common eccrine glands produce cooling
  sweat
• Typically forehead, back, neck

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Sweat contd

• Apocrine glands develop a scent
• Activate at puberty
• Axilla and groin
• Open into hair follicles

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Cutaneous Membrane
Figure 6.2
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Modified sweat glands

• Ceruminous (earwax)
• Mammary (breast milk)

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Temperature regulation

• Skin primarily involved
• Radiation
• Conduction transfer heat to surrounding objects
• Convection circulating air due to heating
• Evaporation sweat

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Skin color

• Melanin
• Everyone has nearly same number of melanocytes
  difference in number and size of granules
• Lack of pigment albinism. Affects skin, hair,
  eyes.

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Wounds

• Mechanisms vary, but inflammation is normal part
  of process
• Increases oxygen/ nutrient availablility

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Burns

• First degree epidermis. Usually heals
  completely
• Second degree destroys some epidermis, damages
  dermis often get blistering.

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• Third degree destroys epidermis and dermis
• must try to heal from edges if no repair
• Grafting usually best option (from self)

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Skin aging

• Epidermis thins
• Secretory cells yield age spots
• Dermis thins wrinkling
• Healing delayed
• Skin dries (less prod. From sebaceous glands
• Melanin decreases (gray hair)

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• Hair growth slows
• Nail beds dull and harden due to diminished blood
  supply
• Decreased receptorsdecreased sensation
• Temperature regulation worsens