Chapter 5 Integumentry System.docx

Body Membranes (end of chapter 4) Membranes - thin sheet like structures consisting of an epithelia overlying a connective tissue (exception). Serous Membranes found lining body cavities that do not open up directly to the outside. each type of serous membrane consists of two layers which are con...

Body Membranes (end of chapter 4) Membranes - thin sheet like structures consisting of an epithelia overlying a connective tissue (exception). Serous Membranes found lining body cavities that do not open up directly to the outside. each type of serous membrane consists of two layers which are continuous with each other. Parietal layer: linings the wall of the cavity. Visceral layer: covers the organs/structures inside the cavity. Balloon Drawing produce a lubricating watery fluid located between the two layers Types: Peritoneum – serous membrane associated with the abdominopelvic cavity Pleura – serous membrane associated with the pleural cavities. Pericardium – serous membrane associated with the pericardial Mucous Membranes (Mucosa) found lining cavities that directly open up to the outside of the body “moist” membranes bathed by fluid some contain goblet cells (mucus secreting cells) examples: digestive, respiratory and urogenital tracts Synovial Membranes – form the inner lining of joint cavities. (connective tissue only) Covered in chapter 8 Cutaneous Membranes an organ of the integumentary system - Skin (See Chapter 5) Integumentary System (Chapter 5) The Integumentary system is composed skin and other various accessory organs. These accessory organs include sweat glands, oil glands, hair, finger nails and toe nails. Characteristic of Skin has a surface area of 1.2 to 2.2 square meters (varies) makes up about 7% of overall body weight 1.5 – 4.0 mm thick Primary Skin Functions Protection against Invading pathogens (cell junctions) Water loss (keratin) Ultraviolet radiation (melanin) Helps to regulate body temperature House receptors for general cutaneous sensations (heat, cold, pain, Synthesizes various chemicals touch, pressure) Excretes some wastes Skin Layer Epidermis - outer most layer composed primarily of a stratified squamous epithelium. avascular and limited sensory innervation divided into 4 (thin skin) or 5 (thick skin) layers depending on location thick skin – located in areas subject to pressure /abrasion (palms of hands, fingertips, plantar surface of foot) thin skin – everywhere else Sublayers Stratum Basale - Basal Cell Layer the deepest single cell layer of cells. In contact with basement membrane. Cuboidal in shape. also called the germinating layer as these cells actively divide (mitosis) to form keratinocytes. keratinocytes give rise to all other layers as continued division pushes these cells toward the outer (apical) surface. Keratinocytes are held together by desmosomes and some tight junctions. They produce the fibrous protein Keratin and glycolipids which along with the cell junctions act as a waterproofing barrier for skin. scattered amongst the basal cells are pigment producing cells called Melanocytes. These cells produce melanin which is responsible in part to skin color. *** SEE MELANIN POWERPOINT ON D2L *** As newly formed Keratinocytes are pushed away from the stratum basale they get cut off from their nutrient lifeline. As a result they die. Stratum Corneum (horny layer) – the outermost layer of skin. approximately 20-30 layers of dead anucleated keratinized cells. makes up to 75% of the thickness of skin. sheds off regularly (dandruff, flakes of skin In a lifetime, the average person sheds about 40lbs of dead skin flakes. (bed bug food) Dermis - connective tissue layer found below the epidermis semi-fluid matrix with embedded protein fibers it contains many of the connective tissue proper cells (fibroblast, macrophages) Sublayers Papillary dermis – outer most superficial layer consisting of areolar CT and small blood vessels. Its outer surface form projections called dermal papillae. The stratum basale follows the contour of the dermal papillae. Contain dermal ridges that along with epidermal ridges for friction lines (fingerprints) Reticular dermis – accounts for 80% of the dermis thickness. Contains collagen fibers in bundles and networks (dense irregular CT). Blood vessel networks (plexus) found at bottom border provide nourishment. Contains flexure lines where dermis is tightly attached to underlying structures at joints. Sweat Glands – tiny tube-like exocrine glands with coiled ends lined with epithelial cells that produce and release sweat. also called sudoriferous glands. found everywhere but nipples and external genitalia approximately 3 million sweat gland per person sweat contains mostly water, salts, antimicrobial substances and small amounts of waste products. Types: See Table 5.1, pg. 162 Eccrine Sweat Glands – most numerous sweat gland activated in times of elevated body temperature. most open up directly onto skin surface by way of a pore found everywhere but especially on forehead, palms, soles of feet produce much sweat on hot days and during physical activity release sweat by way of exocytosis (merocrine release) Apocrine Sweat Glands – approx.2000 become active at puberty produce sweat when a person is emotionally upset, frightened, in pain and during sexual arousal. most open up into hair follicles B. Sebaceous Gland - “Oil Glands” groups of specialized epithelial cells associated with hair follicles. release a fatty oil like substance called Sebum. sebum helps keep hair and skin soft and pliable. found throughout the body except on the palms of your hands and soles of your feet. overactive and inflamed sebaceous glands cause acne. C. Hair Follicles - present on all skin surfaces except palms, lips, nipples, parts of external reproductive organs tube like depressions of the epidermis and into dermis contain the hair root which grows from dividing cells at the base of the follicle (hair papilla). cells move upward from the papilla, become keratinized, and then die. the part of the hair strand above the surface of the follicle is called the shaft. hair color is genetically determined by the amount of melanin produced by the melanocytes. Other minor pigments are involved Dark hair = much melanin Blonde hair = little melanin White hair = no melanin Red hair = iron pigment in hair Gray hair = mixture of pigmented & nonpigmented hair D. Arrector Pili Muscle bundles of smooth muscle fibers attached to the follicle on one end and the dense irregular CT framework of the papillary layer on the other end. when contract causes the hair strand to stand up and the surface of the skin above it to bulge upward. (Goose bumps) contact when a person is emotionally upset (scared) or cold. as studied already an effector for body thermoregulation. E. Sensory Receptor Respond to changes in the surrounding environment. most arte limited to the dermis layer Types: 1. Touch Merkel’s disk, Meissner’s corpuscles 2. Pressure Pacinian corpuscle 3. Heat Ruffini’s endings, Pain nerve ending (extreme) 4. Cold Krause end bulbs, Pain nerve endings (extreme) 5. Pain Free nerve endings 3. Subcutaneous Layer “ Hypodermis” consists of a loose fibrous connective tissue and adipose the collagen and elastic fibers are continuous with dermis adipose thickness varies from one body region to another eyelids lack adipose contain major blood vessels supplying skin Common Skin Disorders 1. Acne inflammatory disease of sebaceous glands bacteria thriving on sebaceous gland secretions as well as sex hormones increase secretion rates. Most prevalent at puberty, as sex hormones (androgens) increase gland size and activity 2. Athletes Foot a fungus infection often present on the soles and between the toes of the feet 3. Decubitus Ulcers tissue damage and ulcerations as a result of deficiency of blood due to prolonged pressure against an underlying bony projection most frequently seen in bedridden patients for long periods of time common areas involved are skin over the sacrum, heels, ankles, buttocks and hips 4. Impetigo highly contagious bacterial skin infection most commonly found in children. characterized by pus-filled sacs (pustules) that rupture and become crusted over. 5. Moles pigmented tumors found in skin vary in color from yellow to brown to black average about 20 per person grow slowly over a period of time, remain stable for a long period of time and then slowly diminish in size 6. Warts result of a viral invasion of the skin causing epithelial cells to proliferate. most regress spontaneously genital warts (herpes virus) can be spread through sexual contact 7.Burns Tissue damage due to thermal (heat), electrical, radioactive, or chemical agents. These agents can destroy the proteins in exposed cells causing injury or death to the cells. Types: Partial thickness burns a. first degree burn only epidermis is affected characterized by mild pain and erythema (redness) will heal in two to three days and may be accompanied by flaking and peeling. b. second degree burn extends through the entire epidermis and part of the dermis Erythema, pain and blistering develops in the area of the damaged skin Heals within 10 to 14 days with little scarring depending on extent of burn Full thickness burns c. third degree burn entire thickness of skin is destroyed surface is leathery and may be tan, brown or black in appearance no pain in immediate area because pain receptors are destroyed regeneration of tissue is slow with much scarring even with grafts Major concerns in cases of severe burns 1. body fluid loss - intravenous administration of balanced salt solution is given 2. heat loss - place patient in warm environment Bacterial infection - application of antibacterial dressings Burns are considered critical if any of the following conditions are met: 1. over 25% of the body has second degree burns 2. over 10% of the body has third degree burns 3. there are third degree burns of the face, hands, or feet Skin Cancers: See Textbook Pg 165, Know 3 main types and characteristics