The Integumentary System

Chapter 36.3

• Organs are two or more tissues which together perform a specialized function.

• Epithelial membranes are thin structures that usually contain both epithelial and connective tissue.

• Mucous membranes – Line cavities that open to the exterior– Layer of epithelium over connective tissue;

epithelium varies with location– Tight junctions and goblet cells

• Cutaneous membrane is the skin– the major organ of the integumentary system

• Integumentary system is the skin and the organs derived from it (hair, glands, nails)

• One of the largest organs– 2 square meters; 10-11 lbs.– Largest sense organ in the body

• The study of the skin is Dermatology

Functions:1. Regulation of body temperature

– Cellular metabolism produces heat as a waste product .

– High temperature• Dilate surface blood vessels• Sweating

– Low temperature• Surface vessels constrict• shivering

2. Protectionphysical abrasiondehydrationultraviolet radiation

3. Sensationtouchvibrationpain temperature

4. Excretion

5. Immunity/ Resistance

6. Blood Reservoir8-10 % in a resting adult

7. Synthesis of vitamin Duv lightaids absorption of calcium

Anatomy

• Epidermis Skin• Dermis• Subcutaneous layer or hypodermis

Dermis• Connective tissue layer• Collagen and elastic fibers, nerves, blood

vessels, muscle fibers, adipose cells, hair follicles and glands.

Accessory organs or epidermal derivatives

• Hairs– Epidermal growths that function in protection– Shaft, root, and folllicle– Sebaceous glands, arrector pili muscle, and

hair root plexus (touch)– Hair growth and replacement have a cyclical

pattern– ‘male-pattern’ baldness

Nails

• Plates of highly packed, keratinized cells• Protection, scratching, & manipulation• Formed by cells in nail bed called the

matrix ( in area of lunula)• 1 mm / week• Eponychium - cuticle

Skin Glands

• Sebaceous (oil) glands– Usually connected to hair follicles– Holocrine glands– Fats, cholesterol, proteins, salts, and cell

debris– Moistens hair and waterproofs skin

Skin color

• Genetic factors– Same number of melanocytes– Albinism

• Environmental factors– Uv light or x-rays

Wound healing

• Inflammation– Blood vessels dilate and become permeable

• Heat, redness, swelling and pain

• Shallow cuts– Epithelial cells migrate– Contact inhibition

Deeper wounds

• Inflammatory phase– Fibrin forms clot

• Migratory phase– Fibroblasts make granulation tissue

• Proliferative phase• Maturation phase• Scars – hypertrophic scar

– keloid

Burns

• First degree or partial thickness burn– Only epidermis is damaged– Erythema, mild edema, surface layer shed– Healing – a few days to two weeks– No scarring

• Second degree- deep partial-layer burn– Destroys epidermis– Blisters form – Healing depends on survival of accessory

organs– No scars unless infected

• Third degree or full-thickness burn– Destroys epidermis, dermis and accessory

organs of the skin– Healing occurs from margins inward– Skin grafting may be needed

• Autograft• Homograft

• Rule of Nines