CH 05 THE INTEGUMENTARY SYSTEM

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1 CH 05 THE INTEGUMENTARY SYSTEM This system consists of skin and its derivatives. The skin is one of the largest organs of the body in terms of surface area. The functions of the integumentary system include: (1) protection, (2) temperature control, (3) receipt of stimuli, (4) excretion of salts and water, and (5) production of vitamin D. The skin varies in thickness from mm and consists of two layers: (1) the epidermis and (2) the dermis. The hypodermis is superficial CT that underlies below the skin. EPIDERMIS The epidermis is the outermost layer of the skin and is composed primarily of stratified squamous epithelium. It is generally 4-5 layers (not cells) thick. Avascular Thick Skin Thin Skin Layers of Epidermis Stratum Corneum *Stratum Lucidum Stratum Granulosum Stratum Spinosum Stratum Germinativum Stratum Basale Types of Cells Keratinocytes Dendritic Cells Langerhans Cells Melanocytes Melanosomes Melanin Merkel Cells 29

2 DERMIS The dermis helps bind the body together. It is highly vascularized and richly innervated. It contains hair follicles, sensory receptors and glands. It is a connective tissue (CT) layer. There are specific skin appendages associated with the epidermal/dermal layers and they include: (1) hair and hair follicles, nails, sudoriferous (sweat; eccrine and apocrine) glands and sebaceous (oil) glands. Layers Papillary Layer Dermal Papillae Meissner s Corpuscles Reticular Layer Skin Appendages Hair (Pili) Sing: Pilus Hair Follicles Arrector Pili Hair Bulb Root Hair Plexus Nails Eponychium Hyponychium Lunula Glands GLANDS: Sudoriferous Glands Sweat glands ; Merocrine. (1) Eccrine (2) Apocrine 30

3 Ceruminous Mammary Pheromone-producing Sebaceous Glands Oil-producing glands. Sebum 31

4 DISORDERS/DISEASES Athlete s foot Boils/Carbuncles Burns Cold sores Contact dermatitis Eczema Impetigo Moles Porphyria Psoriasis Ringworm Rosacea A/k/a ringworm when found on the skin in areas other than between the toes. Caused by a fungus organism. Inflammation of hair follicles and sebaceous glands. Common on the neck. Typically caused by Staphlococcus aureus. Threats: fluid loss and infection. Denature cell proteins and cause cellular death. Rule of nines: Establish body fluid loss by establishing extent of burn. Degrees of burns: First: only epidermal, second: epidermal and upper dermal and third: full skin involvement. Caused by a herpes virus. Small blisters on a cutaneous (skin) nerve. Dormant until activated by stress and/or illness. Caused by exposure to chemicals that provoke allergic responses (itching, redness and swelling). A hypersensitivity response that produces weeping skin lesions. Onset in 90% of cases occurs prior to age 5. Pink water-filled lesions commonly found around the mouth and nose that develop a yellow crust and eventually rupture. Caused by Staphlococcus aureus. A benign (not cancer) growth on the skin that is formed by a cluster of melanocytes. A mole is usually dark and may be raised from the skin. Also called nevus. Moles are usually pink, tan, brown, or flesh-colored. Vampires, werewolves. An inherited disease in which the person lacks the heme portion of the hemoglobin molecules found in red blood cells that transport oxygen and carbon dioxide. Affects approximately 1/25,000 persons. Enzymes for production of heme are lacking, allowing intermediate chemicals from the production pathway to build up and spill into circulation, thereby causing lesions. Sunlight aggravates these intermediates (porphyrins). Garlic aggravates symptoms. Chronic inflammation of skin causing raised red lesions covered with dry silvery scales. A new generation drug known as efalizumab (Raptiva) has been approved (1/2004) to treat psoriasis, eczema, genital warts and skin cancers. The cause for these disorders is an immune system irregularity in which T- cells cause inflammation by activating inappropriately. Raptiva targets T-cells and suppresses T-cell production/release of cytokines. A/k/a athlete s foot when found on the skin in areas other than between the toes. Caused by a fungus organism. Chronic inflammation of the facial region. Affects skin and eyes. Skin cancer Types of skin cancer include Basal cell Stratum basale cell proliferation. 32

5 Malignant melanoma Cancer of melanocytes. Most dangerous form. Starts in cells of stratum germinativum. Squamous cell Keratinocytes. Will metastasize to lymph nodes if not caught. Growth starts in cells of stratum spinosum. ABCD Rule: Asymmetry, border irregularity, color (multi = bad news) and diameter (larger than 6mm is not good). 33