INTEGUMENTARY SYSTEM

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INTEGUMENTARY SYSTEM

• The skin is the largest organ.

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Skin Functions

• Physical barrier
• General senses touch, pressure, pain,
  temperature
• Vitamin D source
• Temperature regulation
• Excretion of wastes

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Types of cells

• Keratinocytes
• produce keratin
• totally replaces epidermis every 25-45 days
• Melanocytes
• produce melanin
• Langerhans
• dermal macrophages
• Merkel cells
• sensory receptors for touch

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Skin Layers

• Epidermis - Stratified squamous epithelium that
  is keratinized
• Dermis - Irregular dense fibrous connective tissue

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Major Layers of Skin

• Epidermis
• stratum corneum
• outermost
• thickest
• dead, flaky, dandruff
• stratum lucidum
• (clear)
• stratum granulosum
• increased keratinization

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Major Layers of Skin

• Epidermis
• stratum spinosum
• (prickly layer)
• stratum basale
• (stratum germinativum)
• mitotic division
• Contains melanocytes

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Skin Layers

• Dermis
• Papillary layer contains
• Dermal papillae
• Meissners corpuscles (touch receptors)
• Reticular layer
• Arteries
• Veins
• Glands
• Pacinian corpuscles (pressure receptors)

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Skin Color

• Melanin
• Yellowish to reddish-brown to black
• Racial differences result from kind and amount of
  melanin
• Freckles local accumulation of melanin
• Melanin increase due to damage from ultraviolet
  radiation
• Excessive exposure to sun damages elastin fibers,
  depresses immune system, and alters DNA possibly
  leading to skin cancer

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• Carotene
• Yellowish, orange
• Accumulation due to diet
• Hemoglobin - reddish

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Color variations

• Redness (Erythema)
• blushing, fever, inflammation, allergy
• Pallor
• fear, anger, stress, anemia
• Jaundice
• yellowish color due to bile liver disorder
• Bronzing
• Addisons disease adrenal cortex disorder
• Bruises (hematoma)
• clotted blood beneath skin

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Accessory Structures

• Sudoriferous (Sweat) Glands
• Eccrine glands
• covers most of body especially hands, feet, and
  head
• Eccrine secretion contains water, salts, vitamin
  C, antibodies, waste (urea, uric acid, ammonia),
  and lactic acid

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Accessory Structures

• Sudoriferous (Sweat) Glands
• Apocrine glands (axial and genital areas)
• Apocrine secretions add fatty substances and
  proteins
• Breakdown of aprocrine secretions by bacteria
  causes body odor
• Begin functioning at puberty

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Accessory Structures

• Specialized Sudoriferous (Sweat) Glands
• Ceruminous glands - secrete wax
• Mammary glands - secrete milk instead of sweat

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• Sebaceous (Oil) Glands
• Secrete sebum
• softens and lubricates skin and hair
• waterproofs
• activated by hormones during puberty
• Whitehead - gland blocked by accumulated sebum
• Blackhead - dried, oxidized sebum
• Acne - active inflammation of sebaceous glands
• Seborrhea (Cradle cap) - overactive sebaceous
  glands

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Hair Hair Follicles

• Structure of hair
• Shaft - projects from skin
• Root - embedded in skin
• 3 layers of ketatinized cells
• medulla - core
• cortex - surrounds core
• cuticle - outermost layer

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Hair Hair Follicles

• Structure of follicle
• Hair bulb - expanded end of follicle
• Hair papilla - dermal papilla protruding into
  hair bulb supplies nutrients stimulates growth
• Hair matrix - produces hair active division
  older cells pushed to top, increase
  keratinization die
• Arrector pili -muscle that raises hairs causes
  goose bumps

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Distribution, Types, Growth of Hair

• Vellus - fine body hair of children and females
• Terminal - coarse hair of scalp and eyebrows
• Growth stimulated by androgens
• Affected by nutrition
• Average growth rate 2mm per week
• Hair Cycles vary
• scalp follicles active approx. 4 yrs
• eyebrow follicles active 3-4 months

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Hair Thinning Baldness

• After 40s resting cycles lengthen
• Hair not replaced as fast as lost
• Baldness alopecia
• Male Pattern Baldness
• Genetically determined
• Sex influenced

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Nails

• Scale-like modifications of epidermis
• Structure
• Free Edge
• Body
• Root
• Nail Bed - epidermis beneath nail body
• Nail Matrix - proximal portion of nail bed
• Lunula
• Nail folds
• Eponychium (cuticle)

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Skin Disorders

• Warts - nonmalignant epithelial growth caused by
  a virus
• Cold sores (fever blisters)
• small fluid-filled blisters around lips mouth
• caused by a herpes simplex virus
• Acne - inflammation of sebaceous glands
• Impetigo - inflamed lesions caused by
  staphylococcus infection
• Decubitus ulcers (bed sores) caused by irritation
  and inadequate circulation

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Skin cancers

• Most skin tumors benign (ex. Warts)
• Basal Cell Carcinoma
• least malignant
• approx. 30 of caucasians will develop this
• 99 cure rate
• Squamous Cell Carcinoma
• Scaly elevation arising from the stratum spinosum

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Cutaneous melanoma

• Arise from melanocytes
• 2 types
• melanocarcinoma
• malignant melanoma
• Irregular growths with variety of pigmentation
  (brown, gray, black, or blue)
• Occur in all age groups, usually in people who
  sunburn easily
• More common in people who get short intense
  exposure to sunlight.
• Survival rate is low.
• May begin in regular skin or mole

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ABCDE rule

• A - Asymmetry
• B - Border irregularity
• C - Color
• D - Diameter
• E - Elevation

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ABCDs of Skin Cancer
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Classification of Burns

• First-degree burns - involves only epidermis
• Second-degree burns - involves both epidermis and
  dermis
• Third-degree burns - complete destruction of both
  layers, probable involvement of subcutaneous
  tissue
• Burns also classified by the extent of burn area
  

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Classification of Burns

• RULE of NINES
• Head 9
• Anterior Thoracic 9
• Posterior Thoracic 9
• Anterior Abdomen 9
• Posterior Abdomen 9
• Left Arm 9
• Right Arm 9
• Anterior Left Leg 9
• Posterior Left Leg 9
• Anterior Right Leg 9
• Posterior Right Leg 9
• Genitals 1