Integumentary System

Membranes Thin, sheet-like structures that: Cover and protect body surfaces Line body cavities Line hollow organs Cover organs Anchor organs Reduce friction

Epithelial Membranes Composed of Epithelial tissues and specialized connective tissue Three types of Epithelial membranes Cutaneous Serous Mucous

Cutaneous Primary organ of the integumentary system (Skin) Makes up roughly 16% of total body weight Three main functions of skin Prevents infection Prevents desiccation Thermoregulation

Serous Found only on surfaces of closed cavities - Parietal: lines body cavities - Visceral: cover surface of organs - Pleura: Serous membranes in the thoracic cavity - Peritoneum: Serous membranes in the abdominal cavity

Mucous Epithelial membranes that line body surfaces opening directly to the exterior Respiratory tract Digestive tract Urinary tract Reproductive tract

Mucous (cont.) Mucocutaneous junction – “Fusion” where skin and mucous membranes meet. Junctions lack accessory organs such as sweat glands and hair Eyelids and nasal openings are examples

Connective Membranes Composed of connective tissue only Synovial membrane

Synovial membrane Lines the spaces between bones and joints Smooth , slick and secrete lubricating synovial fluid

Skin

Epidermis Outermost layer of skin, contains stratum germinativum and stratum corneum

Stratum Germinativum Undergo mitosis and reproduce themselves Move towards the surface and specialize Cells contain cytoplasm Melanocytes produce melanin to protect from U.V.

Movement through the Epidermis Cells move upward from stratum germinativum to stratum corneum (2-4 weeks)

Stratum Corneum Tough outer layer of epidermis Cytoplasm in cells are replaced by keratin Tough and waterproof Roughly 40,000 cells are lost per minute 10 lbs per year!!

Dermal-epidermal junction Thin area “glues” epidermis to dermis If this area is damaged, blisters form

Hair shaft Sudoriforis gland

Dermis Mostly connective tissue Stretchable and elastic Fingerprints develop here (dermal papillae) Most of the appendages of skin are located here.

Appendages of Skin Hair Follicles - layer of skin that holds the hair Papilla of Hair – site of hair growth Hair Shaft- visible part of hair Arrector Pili – muscle attached to hair (goose bumps) Meissner’s Corpuscle – senses light touch Sebaceous Glands – secrete oil (sebum) to prevent the skin from drying Sudoriforis Glands

Sudoriferous Glands Eccrine Apocrine Most numerous Distributed over the total body surface Produce perspiration Eliminates ammonia and uric acid Maintains constant temperature Apocrine Found in armpit and around the genitals Secrete thicker, milky secretion

Subcutaneous Fatty Tissue Insulates the body from extremes of heat and cold Source of stored NRG Pads and protects underlying tissues

Functions of Integumentary System Protection Thermoregulation * Prevent infection * Sense organ activity Prevent desiccation *

Disorders of the Skin

Lesions Any measurable variation from the normal structure of skin Freckles Warts Blisters Scratch Acne

Burns Damage to the skin resulting from: Extreme heat Extreme cold Overexposure to U.V. rays Contact with electric current Chemicals

1st degree Minor discomfort Reddening of skin Mostly epidermis damaged Tissue destruction minimal Example - sunburn

2nd degree Blisters Severe pain Damage to appendages of skin Deep epidermis and dermis damaged

3rd degree Complete destruction of the epidermis, dermis, and part of the SCFT Lesions are insensitive to pain Patients rarely die from the burn itself (complications)

“Rule of Nines” Used to determine the extent of a burn

Infections The skin is the body’s first line of defense so it is commonly infected Impetigo: staph infection Tinea: Ringworm, jock itch, athlete’s foot Warts: caused by the papilloma virus

Skin Cancer Abnormal cells reproduce uncontrollably Risk factors include: Genetic predetermination Excessive exposure to UV radiation Stress

Squamous cell carcinoma Most common type of skin cancer Slow growing Cancer will metastasize (invade other organs) if not treated

Basal cell carcinoma Usually occurs on the upper face Begins at basal layer of stratum germinativum Less likely to metastasize than other skin cancers

Melanoma Most serious form of skin cancer Causes death in 1:4 cases Often develops from moles