Skin and membrane lesson reviewer (integumentary)

Integumentary System

•Skin (cutaneous membrane)

• •Skin derivatives

• Sweat glands

• Oil glands

• Hair

• Nails

Skin Functions

•Protects deeper tissues from:

• Mechanical damage (bumps)

• Chemical damage (acids and bases)

• Bacterial damage

• Ultraviolet radiation (sunlight)

• Thermal damage (heat or cold)

• Dessication (drying out)

Skin Functions

•Aids in body heat loss….

or heat retention as controlled by the nervous system

•Aids in excretion of urea and uric acid

•Synthesizes vitamin D

Skin Structure

•Epidermis—outer layer

• Stratified squamous epithelium

• Cornified or keratinized (hardened by

• keratin) to prevent water loss

• Avascular

• Most cells are keratinocytes

•Dermis

• Dense connective tissue

Skin Structure

•Subcutaneous tissue (hypodermis) is deep to dermis

• Not technically part of the skin

• Anchors skin to underlying organs

• Composed mostly of adipose tissue

Layers of the Epidermis

•Stratum basale (stratum germinativum)

• Deepest layer of epidermis

• Lies next to dermis

• Wavy borderline with the dermis anchors the two together

• Cells undergoing mitosis

• Daughter cells are pushed upward to become the more superficial layers

Layers of the Epidermis

•Stratum lucidum

• Formed from dead cells of the deeper strata

• Occurs only in thick, hairless skin of the palms of hands and soles of feet

Layers of the Epidermis

•Stratum corneum

•Outermost layer of epidermis

•Shingle-like dead cells are filled with keratin (protective protein prevents water loss from skin)

Layers of the Epidermis

•Summary of layers from deepest to most superficial

•Stratum basale

•Stratum spinosum

•Stratum granulosum

•Stratum lucidum (thick, hairless skin only)

•Stratum corneum

Melanin:

•Pigment (melanin) produced by melanocytes

•Melanocytes are mostly in the stratum basale

•Color is yellow to brown to black

•Amount of melanin produced depends upon genetics and exposure to sunlight

Dermis

• Two layers (papillary, retucular)

• Papillary layer (upper dermal region)

• Projections called dermal papillae

• Some contain capillary loops

• Others house pain receptors and touch receptors

• Reticular layer (deepest skin layer):

•Blood vessels

•Sweat and oil glands

• Deep pressure receptors

Dermis

•Overall dermis structure

•Collagen and elastic fibers located throughout the dermis

•Collagen fibers give skin its toughness

•Elastic fibers give skin elasticity

•Blood vessels play a role in body temperature regulation

Receptors Present in the Skin

• Meissner’s corpuscles

• Touch receptors

•Pacinian corpuscles

• Pain receptors

• Ruffini’s corpuscles

• Heat receptors

•End Bulbs of Krause

• Cold receptors

• Merkel’s disk

• Texture receptors

Normal Skin Color Determinants

• Melanin

• Yellow, brown, or black pigments

• Carotene

• Orange-yellow pigment from some vegetables

• Hemoglobin

• Red coloring from blood cells in dermal capillaries

• Oxygen content determines the extent of red coloring

•Redness (erythema)—

due to embarrassment, inflammation, hypertension, fever, or allergy

•Pallor (blanching)—

due to emotional stress such as fear, anemia, low blood pressure, impaired blood flow to an area

•Jaundice (yellowing)—

liver disorder

•Bruises—

Hematomas

Skin Appendages

•Cutaneous glands are..

all exocrine glands

• Sebaceous glands

• Sweat glands

•Hair

•Hair follicles

•Nails

Appendages of the Skin

•Oil (sebaceous) glands

•Produce oil (sebum)

• Lubricant for skin

• Prevents brittle hair

• Kills bacteria

•Most have ducts that empty into hair follicles; others open directly onto skin surface

•Glands are activated at puberty

Appendages of the Skin

•Sweat (sudoriferous) glands p…

•Produce sweat

•Widely distributed in skin

Appendages of the Skin

•Two types of sudoriferous glands (Eccrine, Apocrine)

•Eccrine

• Open via duct to pore on skin surface

• Produce sweat (clear)

•Apocrine

• Ducts empty into hair follicles

• Begin to function at puberty

• Release sweat that also contains fatty acids and proteins (milky/yellowish color)

Sweat and Its Function

• Composition

• Mostly water

• Salts and vitamin C

• Some metabolic waste

• Fatty acids and proteins (apocrine only)

• Function

• Helps dissipate excess heat

• Excretes waste products

• Acidic nature inhibits bacteria growth

•Odor is from associated bacteria

Appendages of the Skin

•Hair

• Produced by hair follicle

• Consists of hard keratinized epithelial cells

• Melanocytes provide pigment for hair color

• Hair grows in the matrix of the hair bulb in stratum basale

•Hair anatomy

• Central medulla

• Cortex surrounds medulla

• Cuticle on outside of cortex

• Most heavily keratinized

Skin Homeostatic Imbalances

•Burns

•Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals

•Associated dangers

• Dehydration

• Electrolyte imbalance

• Circulatory shock

Rule of Nines

•Way to determine the extent of burns

•Body is divided into 11 areas for quick estimation

•Each area represents about 9 percent of total body surface area

Severity of Burns

• First-degree burns

• Only epidermis is damaged

• Skin is red and swollen

Severity of Burns

• Second-degree burns

•Epidermis and upper dermis are damaged

•Skin is red with blisters

Severity of Burns

•Third-degree burns

• Destroys entire skin layer; burned area is painless

•Burn is gray-white or black

Critical Burns

•Burns are considered critical if

• Over 25 percent of body has second-degree burns

• Over 10 percent of the body has third- degree burns

• There are third-degree burns of the face, hands, or feet

Skin Homeostatic Imbalances

•Infections

•Athlete’s foot (tinea pedis)

• Caused by fungal infection

•Boils and carbuncles

• Caused by bacterial infection

•Cold sores

• Caused by virus

Skin Homeostatic Imbalances

•Infections and allergies

•Contact dermatitis •Exposures cause allergic reaction

Impertigo •Caused by bacterial infection

•Psoriasis •Cause is unknown •Triggered by trauma, infection, stress

Skin Cancer

•Cancer—abnormal cell mass

•Classified two ways

•Benign

• Does not spread (encapsulated)

•Malignant

• Metastasized (moves) to other parts of the body

•Skin cancer is the most common type of cancer

Skin Cancer Types

•Basal cell carcinoma

•Least malignant

•Most common type

•Arises from stratum basale

Skin Cancer Types

•Squamous cell carcinoma

• Metastasizes to lymph nodes if not removed

• Early removal allows a good chance of cure

• Believed to be sun-induced

• Arises from stratum spinosum

Skin Cancer Types

•Malignant melanoma

• Most deadly of skin cancers

• Cancer of melanocytes

• Metastasizes rapidly to lymph and blood vessels

• Detection uses ABCD rule

ABCD Rule

A = Asymmetry

• Two sides of pigmented mole do not match

B = Border irregularity

• Borders of mole are not smooth

C = Color

• Different colors in pigmented area

D = Diameter

• Spot is larger then 6 mm in diameter