Skin Integumentary System Integumentary System

objectives Describe the functions of the skin. Describe the structures found in the two layers of skin. Explain how the skin serves as a channel of excretion. Describe the action of the sweat glands. Describe some common skin disorders. Define the key words that relate to this chapter.

The skin is our protective covering and is called the integument or integumentary system or cutaneous membrane. It is tough, pliable, and multifunctional.

Functions of the skin Skin is a covering for deeper tissues protecting them fro dehydration. Helps regulate body temperature by controlling the amount of heat loss. Evaporation , in the form of perspiration, helps decrease excess body heat. Skin helps manufacture vitamin D. UV on the skin is necessary for the first stages of vitamin D formation.

Skin is the site of many nerve endings Skin is the site of many nerve endings. It contains about 72 feet of nerves and hundreds of receptors. Skin has tissues for the temporary storage of fat, glucose, water, and salts…most of these substances are later absorbed by the blood and transported to other parts of the body. Skin is designed to screen out harmful UV. Skin has special properties to absorb certain drugs and chemical substances.

Structure of the Skin Two layers.. Epidermis is the outermost layer of skin and is made up of epithelial cells with no blood vessels present. The dermis also called the true skin, is made of connective tissue and is vascular.

epidermis The epidermis consists of 4 distinct cell types and 5 layers. The thickness varies from eyelids being the thinnest to the thickest on the palms of your hands and feet. The surface layer consists of dead cells rich in keratin. Keratin is a protein that renders the skin dry and provides a waterproof covering as well as being a barrier against bacteria, abrasions, and UV light.

The epidural cells are as follows… Keratinocytes – which comprise most of the epidermis and produce the protein keratin. Merkel cells - sensory receptors for touch. Melanocytes produce the protein melanin which protects the skin against the ultraviolet rays of the sun. Langerhans cells ( not the same as islets of Langerhans in the pancreas) which are the macrophages that are effective in the defense of the skin against microorganisms.

dermis The thicker, inner layer of the skin. It contains matted masses of connective tissue, collagen bands, elastic fibers, nerve endings, muscles, hair follicles, oil and sweat glands, and fat cells. The nerve endings for touch are closer to the epidermis so you can feel someone's touch while pressure receptors are deeper in the dermal layer…this explains why you can sit for a long period of time before you become too uncomfortable.

Appendages of the Skin Hair Nails Sudoriferous (sweat) glands – perspiration is 99% water with only a small quantity of salt and organic materials (waste products)…the amt of water lost per day through the skin is 500ml. Sebaceous (oil) glands and their ducts – sebum is the oily substance secreted by the sebaceous glands. Side note…under arm odor is caused by the interaction of bacteria on perspiration…to decrease the odor antiperspirants will decrease the sweat and deodorant soaps will kiss the bacteria.

Hair – each hair follicle has a smooth muscle called the arrector pili muscle which when stimulated, contracts causing a “goose bump”….at the same time producing a small amount of oil.

Nails – a nail is formed in the nail bed…the elongated epidermal cells fuse together to form hard keratonized plates.

Sudoriferous (sweat) glands – perspiration is 99% water with only a small quantity of salt and organic materials (waste products)…the amt of water lost per day through the skin is 500ml.

Sebaceous (oil) glands and their ducts – sebum is the oily substance secreted by the sebaceous glands.

handwashing The number one way to prevent the spread of disease. The least amount of time you should wash is 10 – 30 seconds. If you have been in contact with infectious material you should wash from 2 to 4 minutes.

Skin and Aging The skin present the most visible signs of aging. As one ages, the sebaceous glands secrete less lubrication and the outer layer of the skin becomes more fragile and dry. The elastin fibers shrink, becoming more rigid and leading to a loss of elasticity in the sin. Loss of sebaceous fat results in lines, wrinkles, and sagging. The melanocytes' decrease, making the skin more sensitive to UV rays of the sun.

Disorders and Diseases Acne vularis Athlete’s Foot Dermatitis Eczema Impetigo psoriasis Ringworm Uticaria Boils Herpes Shingles (herpes zoster) Skin cancer – basal cell and squamous cell Skin cancer – malignant melanoma and macule Burns – first, second, third degree and rule of nines Pressure ulcer – stages I-IV Bulla and vesicle Nodules and tumors Pustule and papule