Chapter 4

The integumentary system is a dynamic continuous body covering composed of: Blood vessels Connective tissue structures Glands Hair Nails Skin Overview Chapter 4 – The Skin and Its Parts

The skin has three distinct layers: the epidermis, the dermis, and the hypodermis (or subcutaneous layer). The Integumentary System Chapter 4 – The Skin and Its Parts

Epidermis: Outermost layer, where new skin cells are continually produced The Integumentary System Chapter 4 – The Skin and Its Parts

Dermis: Middle layer; composed mostly of connective tissue The Integumentary System Chapter 4 – The Skin and Its Parts

Hypodermis: (also called the subcutaneous layer) Innermost layer, composed of loosely arranged elastic fibers that anchor the skin to underlying tissue The Integumentary System Chapter 4 – The Skin and Its Parts

The four main functions of the integumentary system are: Protection against environmental damage Heat regulation – maintain a constant internal temperature Sensation – receiving stimuli from the environment Waste excretion The Integumentary System Chapter 4 – The Skin and Its Parts

3 types of glands commonly found in the skin: 1.Ceruminous glands Produces a waxy secretion called cerumen Found in the lining of the ear canal 2.Sebaceous glands Produce an oily secretion called sebum Secreted into hair follicles & moves to the surface of the skin 3.Sweat glands GLANDS Chapter 4 – The Skin and Its Parts

2 Types: 1.Apocrine sweat glands  Secrete odorous sweat into the hair follicles of the armpits, navel, and groin regions  Inactive until puberty  Usually tapers off in the elderly SWEAT GLANDS Chapter 4 – The Skin and Its Parts

 Apocrine sweat glands contain chemicals called pheromones, which are believed to play a role in courtship and social behavior ex.) dogs sniffing people Why does your sweat smell so bad?  The secretions are easily broken down by bacteria, which creates body odors. SWEAT GLANDS Chapter 4 – The Skin and Its Parts

2.Eccrine Sweat Glands  Found mostly on the skin of armpits, forehead, palms, and soles  Eccrine sweat gland activity is genetically determined  Human eccrine sweat is composed primarily of water with various concentrations of salts, organic compounds, and wastes, including urea. SWEAT GLANDS Chapter 4 – The Skin and Its Parts

Antiperspirants can be used to reduce the amount of sweat (from both gland types), thereby reducing odors and dampness. How do antiperspirants work? There is an electrical repulsion between a negatively charged ingredient and the negatively charged sweat molecules. Interesting Fact: Chapter 4 – The Skin and Its Parts

Fingernails & toenails are nothing more than a keratin secretion. Keratinocytes at the base of the nail root gradually move up to the surface of the skin. The cells closest to the surface die, flatten, press tightly together, & disintegrate to form the nail body. Fingernails of a healthy person typically grow 1/8 th an inch per month (slightly faster than toenails) NAILS Chapter 4 – The Skin and Its Parts

Aging is due to: Intrinsic factors  aging caused by the natural decline of cells OR Extrinsic factors  aging caused by environmental factors (disease, pollution, sun exposure) One’s lifestyle can accelerate aging. Wellness and Illness over the Life Span Chapter 4 – The Skin and Its Parts

Pathology can be categorized as: Degenerative  refers to diseases that progressively deteriorate tissues  examples include skin cancer, moles,skin tags Genetic  includes acne, psoriasis, spider veins Infectious  diseases including impetigo, ringworm, warts Wellness and Illness over the Life Span

DISORDERS: HOMEOSTATIC IMBALANCES Skin cancer can be caused by excessive exposure to sunlight. Risk factors for skin cancer include skin type, sun exposure, family history, age, and immunological status.

Skin disorders Basal cell carcinoma 30% of Caucasians get this type of skin cancer. Does not metastasize. Squamous Cell carcinoma arises from the keratinocytes in the stratum spinosum. May metastasize (spread to other body parts). Melanoma arises in the melanocytes. Rapidly metastasizes.

Melanocytes Produces melanin for protection from UV radiation. Responsible for skin color. Melanoma.

Melanoma

ABCD Rule A symmetry, B order irregularity, C olor, D iameter

Burns Denaturation of cell proteins. Dehydration, protein loss, and infection. First degree burns only the epidermis (sunburn). Second degree burns epidermis and upper dermis. May include fluid-filled blisters that separate epidermis & dermis. Heals without grafting in 3 to 4 weeks & may scar

Third degree burns = full thickness burns – destroy epidermis, dermis & epidermal derivatives – damaged area is numb (not painful at all) due to loss of sensory nerves -- Skin grafting is almost always necessary.

Types of Burns

Tattoos Tattooing is a permanent coloration of the skin in which a foreign pigment is injected into the dermis.

Possible Dangers of Body Tattoos Infection, allergic reaction to the ink, psoriasis, and dermatitis Diseases such as HIV, AIDS, Hepatitis B and C, and even syphilis Body tattoos can also cause tumors