Chapter 4 – Skin and Body Membranes 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 membranes Connective tissue membranes – synovial membranes

Classification of Body Membranes Epithelial 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 layer Hypodermis – 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 Sebaceous Sudoriferous Eccrine apocrine 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 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

Infections and allergies Homeostatic imbalances of the skin Infections and allergies Boils and carbuncles Athlete’s Foot Cold Sore Impetigo Psoriasis

Decubitus ulcers – restriction of normal blood supply to skin resulting in cell death Bed sores occur in bedridden patients not turned regularly or are dragged across the bed repeatedly Deep (stage III) ulcer

Burns 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

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 hand 2nd degree burns on the leg

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

Squamous Cell Carcinoma Skin Cancer - neoplasm in the skin; single most common type of cancer in humans; 1 in 5 Americans develop cancer American Cancer Society ABCD Rule: Asymmetry Border Color Diameter Basal Cell Carcinoma Squamous Cell Carcinoma Melanoma 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.