Anatomy

Chapter 4 – Skin and Body Membranes

Introduction – Integumentary System

Body membranes cover the surface, line body cavities, form protective sheets around organs

Two major groups:Epithelial membranes – cutaneous (skin or integumentary

system), mucous, and serous membranesConnective tissue membranes – synovial membranes

Classification of Body MembranesEpithelial membranes – covering or lining membranes

Skin

Mucosa

Serous membranes line ventral body cavities closed to interior; occur in pairs

Connective tissue membranes

Synovial membranes No epithelial cells Bursae – lubricating

sacs that reduce movement – related friction

Tendon sheath – tube-like covering over a tendon

Both cushion organs moving against each other during muscle activity

Integumentary System (skin) – Cutaneous

membrane

Structure of the skin:• Stratum basale (stratum

germinativum)• Stratum spinosum• Stratum granulosum• Stratum lucidum• Stratum corneum

• Melanin - pigment

Skin structure Dermis – underlying layerHypodermis – adipose

Skin color

Pigments - three contribute to color Melanin – in epidermis; yellow, reddish brown, black Carotene – in stratum corneum and subcutaneous tissue ; orange-

yellow Hemoglobin – dermal blood vessels; pigment in red blood cells

Influenced by emotional stimuli Redness or erythema Pallor or blanching Jaundice or yellow cast Bruises Cyanosis

Appendages of the skin Cutaneous glands - exocrine glands that release secretions onto skin surface via ducts

Sebaceous Sudoriferous

Eccrine apocrine

Hair and Hair Follicles – scattered all over body; protection

Hair follicle Shaft Matrix arrector pili

Electron micrograph of hair shaft emerging from a follicle on the skin

Nails – scale-like modification of dermis; hoof or claw

Homeostatic imbalances of the skin

Athlete’s Foot

Cold Sore Impetigo

Psoriasis

Boils and carbuncles

Infections and allergies

Decubitus ulcers – restriction of normal blood supply to skin resulting in cell death

Deep (stage III) ulcer

Bed sores occur in bedridden patients not turned regularly or are dragged across the bed repeatedly

Burns - tissue damage and cell death; intense heat, electricity, UV radiation, chemicals.

Rules of Nines - 11 body areas account for approximately 9% of body surface area; 1% genital area

Infection is most important threat and is leading cause of death in burn victims; skin is sterile for 24 hours after a burn

Critical burns• 25% of body has 2nd degree burns• 10% of body has 3rd degree burns• 3rd degree burns on face, hands, or feet

Burns

First Degree Burn - only epidermis is damaged

Sunburn: Red Swollen Heal in 3 days

Second Degree Burn - injury to epidermis and upper region of dermis; red and painful; blisters appear; regrowth can occur; no permanent scars

2nd degree burns on the leg2nd degree burns on the hand

Third Degree Burns - destroy entire thickness of skin; area blanched or blackened; nerve endings destroyed; regeneration not possible

Third degree burn on the neck

Basal Cell Carcinoma Squamous Cell Carcinoma

Melanoma

Skin Cancer - neoplasm in the skin; single most common type of cancer in humans; 1 in 5 Americans develop cancerAmerican Cancer Society ABCD Rule:

Asymmetry Border Color Diameter

A typical mole developing into cancer.

Developmental Aspects of skin and Body Membranes

Lanugo - downy type of hair on fetus; shed by birth; premature babies may still have it.

Vernix caseosa - white, cheesy-looking substance produced by sebaceous glands; protects babies skin while floating in amniotic fluid.