Integumentary System Cutaneous = skin Skin Hair Nails and associated glands Skin is the largest organ of the body 17,000 sq cm –average adult Function: • Protection -prevent vs dehydration,microbes,UV radiation, physical insult • Regulate Temperature • Vitamin D synthesis • Information about environment – extension of the nervous system Skin has 3 distinct sections • Epidermis = layers of stratified squamous epithelial tissue • Dermis = loose connective tissue • Hypodermis [subcutaneous] - adipose tissue Subcutaneous tissue anchors skin to the underlying tissue/organs 1/2 of the body‟s adipose tissue „storage adipose‟ = energy adipose also contributes to cushioning and temperature control aging/maturation = distribution of fat stores changes “baby fat” over whole body male - neck, lower back „love handles‟ female - breast,hips/thighs abdomen Epidermis Epidermis – The outer most layer composed of epithelial cells. It is subdivided in to thin layers called strata and contains no blood vessels Epidermis has 5 distinct layers of cells stratum basale - one layer of cells stratum spinosum - 8-10 layers of cells stratum granulosum - 2-5 layers of cells stratum lucidum - several layers of cells stratum corneum - 25 + layers of cells Specialized cells in epidermis Melanocytes - produce melanin - pigment--- 25% of basal cells Keratinocytes - produce a protein mixture of keratin Langerhans cells - phagocyte Merkel‟s cells - specialized cells associated with nerve endings - detect light touch and pressure melanocyte Stratum Corneum The stratum corneum is the outer most stratum of the epidermis. It is comprised of flat, tough, keratin containing cells that provide a protective layer for the skin. Keratin is a protein that strengthens the cells and is also found in other areas of the body. The cells in this stratum are either dead or dying, as they have no blood vessels to keep them alive. Stratum lucidum Stratum granulosum Stratum corneum Highly pigmented skin keratinocytes Dermis Also called the “true skin.” Is a network of elastic connective tissue that contains blood vessels and nerves, as well as the appendages of the skin. Extensions of the dermis, known as papillae, extend toward the epidermis and form what we know as fingerprints. Dermis has two distinct regions Papillary region: top area loose connective tissue with high % of elastin fibers folds called dermal papillae - ridges for friction/gripping fingerprints Reticular region:connective tissue with collagen and elastin fibers stretch -return to original shape Papillary region Structures in Dermis Blood vessels hair follicles sebaceous glands sweat glands [sudoriferous glands] merocrine - help regulate temperature eccrine - don‟t regulate temperature -odor arrector pili muscle Nerve endings – pain, temperature, touch, vibration other glands: ceruminous glands [modified merocrine] Sweat Glands The technical name for sweat glands is sudoriferous glands. Sudoriferous glands help regulate body temperature through the evaporation of sweat. Secretions of the sweat glands in the groin and armpits also contain cellular debris that produce body odor when broken down by bacteria. Sebaceous Glands Produce sebum, an oily substance that prevents drying of the skin and hair. Blackheads are blocked sebaceous glands full of dried sebum and keratin. Pimples are infected blackheads. Sebaceous cysts may form over time if the glands stays blocked and will continue to increase in size. (until they‟re dealt with) Hair is composed primarily of keratin and covers most of the body. The hair grows from the follicle, a sheath in the dermis. Most follicles have a small muscle associated with it, which allows it to raise forming “goose bumps.” Factoid: eye lashes protect eyes, but also sense when something is coming towards the eye. Grow new eyelashes every 5 weeks. HAIR shaft : part above skin surface root: part below skin surface Nails – extensions of the epidermis Protective & functional The larger the digit, the faster the nail grows Nails Nails are made of hard, keratinized cells and provide protection to the fingers and toes. New cells form continuously in the nail root at the proximal end of the nail. Pigment The color of the skin is controlled by the amount of melanin in the skin. As melanin helps protect the skin from UV rays, the amount of melanin increases with sun exposure. Discolorations Pallor – often decreased blood flow or anemia. Flushing – increased blood flow, often related to exercise,fever, or infection. Cyanosis – blueing of the skin due to decreased oxygenation of the blood. Jaundice – yellowing of the skin from increased bilirubin in the blood often associated with liver disease and hemolytic disease. Carotenemia – excessive intake of carotene containing vegetables, like carrots, leading to an orange cast to the skin. Bronzing/ gray/ brown discolorations – Addison‟s disease, chronic poisonings Lesions are essentially any damage to tissue. Size, shape, height, and/or depth of the lesion are all important aspects in evaluating a skin lesion. Surface Lesions Rash – an area of erythema (redness) of the skin. Eruption – a raised rash, often erythematous. Macules – flat spots, such as in measles and freckles. Surface Lesions Papules – firm, raised areas, such as in chickenpox or pimples Nodules – Large papules Vesicles – blisters full of fluid, such as in poison ivy Pustules – infected vesicles filled with pus, such as in folliculitis Papules from scabies Nodule from Basal Cell Carcinoma of Scalp Herpes simplex induced vesicles Pustules induced by a Group A beta-hemolytic streptococcal infection Deeper Lesions Excoriation – scratches, often associated with intense itching or a psychological disturbance Laceration – a rough, jagged wound from tearing, more than cutting Ulcer – from death of tissue, such as with diabetic and tropical ulcers Fissure – a crack in the skin, such as in athlete‟s foot. Excoriations from Swimmer‟s Itch Fissure Effects of Aging on the Integumentary System •Thinning of the dermis •Decreased elasticity •Wrinkling due to decreased collagen and fat •Thinning, drying, whitening of the hair – by 50 yrs of age, most people will start „graying‟ •Decreased perspiration •Nail growth slows •Decreased blood flow will upset temperature regulation Common Terms to be familiar with • Dermatosis and Dermatitis • Dermatosis is any skin disorder. • Dermatitis is an inflammation of the skin which can have a large variety of causes. Contact Dermatitis from metal Contact Dermatitis from Adhesive Alopecia is the technical term for baldness Aside from hereditary male pattern baldness, alopecia can be caused by: Malnutrition Chemotherapy Approx. 50%of male population will have some Systemic disease degree of balding with It can also be increased age idiopathic B D Tyagi of Bhopal in India The hair growing from the middle of his ears measures an astonishing 10.2cm at its longest point, which is probably long enough for small pony tails.
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