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ANATOMY INTEGUMENTARY SYSTEM Chapter 4 Classifications of Membranes Epithelial Cutaneous Mucosa Serous Connective Synovial Cutaneous Membranes Cutaneous- a dry membrane Outermost protective boundary (skin) Superficial epidermis Keratinized stratified squamous epithelium Underlying dermis Mostly dense connective tissue Mucosa Surface epithelium Type depends on site Underlying loose connective tissue (lamina propria) Lines all body cavities that open to the exterior body surface Often adapted for absorption or secretion Serous Surface simple squamous epithelium Underlying areolar connective tissue Lines open body cavities that are closed to the exterior of the body Serous layers separated by serous fluid Specific Serous Membranes Peritoneum Abdominal cavity Pleura Around the lungs Pericardium Around the heart Connective- Synovial Synovial membrane Connective tissue only Lines fibrous capsules surrounding joints Skin’s Functions Protects deeper tissues from: Mechanical damage Chemical damage Bacterial damage Thermal damage Ultraviolet radiation Desiccation Aids in heat regulation Aids in excretion of urea and uric acid Synthesizes vitamin D Skin Structure Epidermis – outer layer Stratified squamous epithelium Often keratinized (hardened by keratin) Dermis Dense connective tissue Hypodermis (Subcutaneous Tissue) Below the dermis Not part of the skin Anchors skin to underlying organs Composed mostly of adipose tissue Layers of the Epidermis 1. Stratum basale Cells undergoing mitosis Lies next to dermis 2. Stratum spinosum 3. Stratum granulosum 4. Stratum lucidum Occurs only in thick skin 5. Stratum corneum Shingle-like dead cells Dermis Two layers Papillary layer Projections called dermal papillae (fingerprints!) Pain receptors Capillary loops Reticular layer Blood vessels Glands Nerve receptors Melanin Pigment produced by melanocytes Amount produced depends on genetics and sun exposure Yellow, brown, black color Found in stratum basale Normal Skin Determinants Melanin Yellow, brown or black pigments Carotene Orange-yellow pigment from some vegetables Hemoglobin Red coloring from blood cells in dermis capillaries Oxygen content determines the extent of red coloring SWEAT GLANDS aka sudoriferous glands Found over entire skin surface except nipples and part of external genitalia > 2.5 million per person Eccrine sweat glands More numerous, Located EVERYWHERE! Abundant on palms, soles of feet and forehead secretory part of gland coiled in dermis Duct extends to open in a “pore” Apocrine sweat glands Located in armpit and genital areas Begin to function at puberty under influence of androgens Thought to play role in sexual attraction (scent glands in animals) Secrete fatty acids and proteins causing a yellowish color Odorless, but bacteria feast on secretions giving musky odor Sweat and Its Function Composition Mostly water plus salts (NaCl) Some metabolic waste (urea, ammonia, uric acid) Acidic pH 4-6, inhibits bacteria Fatty acids and proteins (apocrine only) Function Helps dissipate excess heat Excretes waste products Acidic nature inhibits bacteria growth SEBACEOUS GLANDS WHAT ARE THEY? aka oil glands secrete an oily substance called sebum sebum is produced within specialized cells and is released as these cells burst; sebaceous glands are thus classified as holocrine glands. Sebum is a mixture of fat and debris of dead fat-producing cells. These cells are constantly replaced by new growth at the base of the glands. sebum is deposited on the hairs inside the follicles and brought up to the surface of the skin along the hair shaft. In hairless areas, the sebum surfaces through ducts or pores Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry, brittle, and cracked. It can also inhibit the growth of microorganisms on skin since it contains antimicrobial substances Found everywhere on the body except the palms of the hands and soles of the feet. At the rim of the eyelids are a specialized form of sebaceous gland that secrete sebum into the tears coating the eye to prevent evaporation. The sebaceous glands of a human fetus in utero secrete a substance called vernix caseosa, a "waxy" or "cheesy" white substance coating the skin of newborns The activity of the sebaceous glands increases during puberty because of heightened levels of androgens (sex hormones). Overactive sebaceous glands can cause skin problems such as acne. The extreme use of anabolic steroids by bodybuilders for muscle gain tend to stimulate the sebaceous glands which can cause acne. A blocked sebaceous gland can result in a sebaceous cyst. Dry skin is caused by underactive oil glands as we get older, as our bodies don't produce these natural oils so effectively. Babies and young children are also often susceptible to dry skin because the sebaceous glands haven't developed properly. Appendages of the Skin Hair Produced by hair bulb Consists of hard keratinized epithelial cells Melanocytes provide pigment for hair color Figure 4.7c Hair Anatomy Central medulla Cortex surrounds medulla Cuticle on outside of cortex Most heavily keratinized Figure 4.7b Associated Hair Structures Hair follicle Dermal and epidermal sheath surround hair root Arrector pilli Smooth muscle Lifts hair upright, “goosebumps” Sebaceous gland Sweat gland Figure 4.7a Appendages of the Skin Nails Scale-like modifications of the epidermis Heavily keratinized Stratum basale extends beneath the nail bed Responsible for growth Lack of pigment makes them colorless Nail Structures Free edge Body Root of nail Eponychium – proximal nail fold that projects onto the nail body Figure 4.9 Skin Homeostatic Imbalances Infections Athletes foot Caused by fungal infection Boils and carbuncles Caused by bacterial infection Cold sores Caused by virus Skin Homeostatic Imbalances Infections and allergies Contact dermatitis Exposures cause allergic reaction Impetigo Caused by bacterial infection Psoriasis Cause is unknown Triggered by trauma, infection, stress BURNS AND SKIN CANCERS BURNS BURNS What are they? What causes them? A burn is damage to your body's tissues caused by heat, chemicals, electricity, sunlight or radiation. Scalds from hot liquids and steam, building fires and flammable liquids and gases are the most common causes of burns. There are three types of burns depending on how severe the burn is and its damage to underlying tissues: First degree Second degree Third degree Rule of Nines Way to determine the extent of burns Body is divided into 11 areas for quick estimation Each area represents about 9% First-degree burns damage only the outer layer of skin-the epidermis Only symptom is redness of skin are painful Example: sunburn Second-degree burns damage the epidermis and the dermis Causes blisters to form as epidermis separates from the dermis Also painful Second degree burns Third-degree burns damage or destroy both layers of skin and tissues underneath patients often require skin grafts usually painless because the nerve endings that supply pain sensation are destroyed Third degree burns Burns can cause swelling, blistering, scarring and, in serious cases, shock and even death. Swelling and blistering come from fluids seeping out of the blood vessels This fluid loss creates one of the greatest dangers from burns-fluid loss and dehydration. Fluid loss can be so great as to lead to depletion of blood volume and shock and dangerously low blood pressure Death is likely if the fluids are not replenished (IV fluid replacement with isotonic saline or plasma) Another great danger of burns is infection because they damage your skin’s protective barrier. Antibiotic creams can prevent or treat infections.. 1st and 2nd degree burns can heal over time without skin grafts since there is enough underlying skin to repair the skin. After a third-degree burn, skin or synthetic grafts may be needed to cover exposed tissue and encourage new skin to grow. This is as good as it will ever get. These scars are for life! SKIN CANCERS Basal Cell Carcinoma Least malignant but MOST COMMON Sun exposed areas Invade the dermis and hypodermis Squamous Cell carcinoma Scaly, reddend papule Sun-induced, metastasizes to lymph nodes Malignant Melanoma Cancer of Melanocytes Only 5% of cancers, but increasing MOST DEADLY (survival 50%) Some develop from moles ABCD’s A= Asymmetry 2 sides do not match B= Border Irregularity Not smooth, indentations C= Color Different colors: reds, tans, blacks, brown D= Diameter larger than 6mm E= Evolution