the integumentary system skin and derivatives sweat glands oil glands hair nails
Post on 26-Dec-2015
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- The Integumentary System Skin and derivatives Sweat Glands Oil Glands Hair Nails
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- Amazing Facts About Skin The skin is waterproof. The outer surface is made of dead cells. House dust is 90% skin flakes! Skin is the largest organ in the body! It weighs 2.5 kg. Skin is elastic. If you laid skin on a flat surface, it would have an area of 2 square meters! Your hair stands on end and you develop goosebumps when the muscles in the hair follicles contract b/c youre cold or scared.
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- Skin Functions Integument means covering Functions are mostly protective: Mechanical damage ex. Cuts Chemical damage Thermal damage burn UV radiation sunlight Bacteria Also insulates and cushions internal organs.
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- Skin Functions Waterproof Keeps water in and keeps water out Temp. regulation Capillaries and sweat glands both release heat from the body Excretion Sweat releases toxins Makes proteins and vitamin D Contains sensors to feel touch, temperature, pain
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- Structure of the Skin The skin is composed of two kinds of tissue: The outer epidermis is made of stratified squamous epithelium The underlying dermis is made up of connective tissue The epidermis and dermis are firmly connected. A burn or friction may cause them to separate resulting in a blister.
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- Structure of the Skin Deep to the dermis is the subcutaneous tissue, or hypodermis, which is mostly adipose tissue (fat). It is not considered part of the skin, but it does protect the organs. absorbs shock and insulates the deeper tissues from extreme temperature changes
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- Epidermis The epidermis is composed of 5 layers called strata. The epidermis has no blood supply of its own, it is avascular. Most cells are keratin cells, which produce keratin Keratin fibrous protein that makes the epidermis tough & protective
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- Epidermis Melanin pigment that ranges in color from yellow to brown to black Produced by special cells called melanocytes When the skin is exposed to sunlight, the melanocytes produce more of the melanin pigment and tanning occurs. Freckles and moles are seen where melanin is concentrated in one spot.
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- Epidermis Excessive sun exposure eventually damages the skin. By causing the elastic fibers to clump, leathery skin forms. It depresses the immune system. Overexposure to the sun can also damage DNA of skin cells, which leads to skin cancer.
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- Dermis The dermis is the strong, stretchy envelope that holds the body together. When you purchase leather goods, you are buying the treated dermis of animals. The dermis varies in thickness very thick on palms of hands and soles of the feet, but is quite thin on the eyelids. The dermis contains blood vessels, sweat and oil glands, pressure receptors, touch receptors, temperature receptors and pain receptors.
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- Dermis Collagen fibers are found throughout the dermis. They are responsible for the toughness of the dermis and give the skin its elasticity. The dermis is supplied with blood vessels that play a role in maintaining body temperature. When body temperature is high, the capillaries become swollen and the skin is reddened and warm. This allows body heat to radiate from the skin surface. If the environment is cool and body heat must be conserved, blood bypasses the dermis capillaries allowing the internal body temperature to remain constant.
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- Appendages of the Skin The skin appendages include oil and sweat glands, hairs and hair follicles, and nails. Each of these appendages arises from the epidermis and plays a role in maintaining homeostasis. Includes: Oil (Sebaceous) Glands Sweat Glands Hair and Hair Follicles Nails
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- Sweat and Oil Glands Sweat and oil glands are exocrine glands (they secrete substances) that release their secretions to the skin surface through ducts. These glands reside in the dermis.
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- Oil Glands Oil glands are found all over the skin, except on the palms of the hands and the soles of the feet Their ducts usually empty into a hair follicle, but some open directly onto the skin surface. The product of the sebaceous glands is called sebum. Sebum keeps the skin soft and moist and keeps the hair from becoming brittle.
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- Oil Glands Sebum also contains chemicals that kill bacteria, so it is important in preventing the bacteria present on the skin surface from invading deeper skin regions. if a sebaceous glands duct becomes blocked by sebum, a whitehead appears if the accumulated material oxidizes and dries, it darkens, forming a blackhead
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- Sweat Glands Widely distributed in the skin More than 2.5 million per person 2 types of sweat glands: Eccrine glands more numerous and found all over the body, produce sweat to regulate body temperature and inhibit the growth of bacteria present on the skin surface Apocrine glands larger than eccrine glands, ducts empty into hair follicles, confined to the axillary (armpit) and genital areas of the body
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- Hair and Hair Follicles Millions of hairs scattered all over the body Hair is a flexible epithelial structure produced by a hair follicle. The part of the hair enclosed in the follicle is called the root. The part projecting from the surface of the scalp or skin is called the shaft. A hair is formed by division of the epithelial cells in the growth zone, called the hair bulb, at the bottom of the follicle.
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- Hair and Hair Follicles The bulk of the hair shaft, like most of the epidermis, is dead material and almost entirely keratinized protein. Each hair consists of a central core called the medulla. The medulla is surrounded by a bulky cortex layer. The cortex is enclosed by the outermost cuticle. Hair pigment is made by melanocytes in the hair bulb, and varying amounts of different types of melanin (yellow, rust, brown, black) combine to produce all varieties of hair color from pale blond to black.
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- Hair and Hair Follicles Humans are born with as many hair follicles as they will ever have. Hairs are among the fastest growing tissues in the body. Hairs have muscles called arrector pili that connect the hair follicle to the dermis. When these muscles contract, the hair is pulled upright causing goosebumps.
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- Nails Scalelike modification of the epidermis, like the hoof or claw of other animals Nails are mostly nonliving material, like hairs. Nails are transparent and nearly colorless, but they look pink because of the rich blood supply in the underlying dermis. The white crescent in the nail is called the lunula. It is a thickened area of the nail.
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- Homeostatic Imbalances of the Skin The skin is only about as thick as a paper towel! But, when the skin is seriously damaged, nearly every system in the body is affected. The skin can develop more than 1000 different disorders. The most common skin disorders result from allergies or bacterial, viral, or fungal infections. Less common problems are burns and skin cancers, but these are also more serious.
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- Infections and Allergies Athletes foot: a fungus infection of the skin on the foot, between the toes Boils: inflammation of hair follicles and sebaceous glands, common on the back of the neck Cold sores: small fluid-filled blisters on the lips/mouth caused by herpes simplex (virus) infection; the virus localizes in a nerve under the skin where it remains inactive until fever, UV radiation, or emotional upset
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- Infections and Allergies Dermatitis: itching, redness, and swelling of the skin that results in blistering; caused by exposure of the skin to chemicals that provoke allergic reactions (such as poison ivy) Impetigo: lesions that form around the mouth and nose; caused by a highly contagious bacterial infection Psoriasis: a chronic condition that may be hereditary; reddened lesions of the skin, attacks are triggered by trauma, infection, hormonal changes and stress
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- Burns A burn is tissue damage and cell death caused by intense heat, electricity, UV radiation, or certain chemicals (such as acids). When the skin is burned, the cells are destroyed. 2 life threatening problems result: The body loses its supply of fluids because they seep from the burned surfaces. This results in dehydration and electrolyte imbalance. Fluids (including blood) must be administered to the patient. Infection is the leading cause of death in burn victims since pathogens, such as bacteria and fungi, easily invade areas where the skin has been destroyed.
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- Burns To determine how much of the body surface is burned, the rule of nines is used. The body is divided into 11 areas. Each accounts for 9% of the total body surface area, plus 1% for the genital region.
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- Burns Burns are classified according to the severity as first, second, or third-degree burns. In first-degree burns, only the epidermis is damaged. the area becomes red and swollen, not usually painful ex. sunburn (usually) Second-degree burns involve injury to the epidermis and the upper region of the dermis. the skin is red and painful, blisters appear regrowth of the epithelium can occur
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- Burns Third-degree burns destroy the entire thickness of the skin also called full-thickness burns burned areas appear blackened or gray- white in color the burned area is not painful since the nerve endings in the area are destroyed regeneration is not possible, skin grafting must be done cover the underlying tissues
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- Burns are considered critical if any of these conditions exist: Over 25% of the body has 2nd degree burns Over 10% of the body has 3rd degree burns, or There are 3rd degree burns of the face, hands, or feet.
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- Skin Cancer Numerous types of tumors Most are benign and do not spread However, some skin tumors are malignant, or cancerous, and they tend to invade other areas of the body. Skin cancer is the single most common type of cancer in humans. Most important risk factor overexposure to ultraviolet radiation Frequent irritation of the skin by infections or chemicals also a predisposing factor for skin cancer
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- 3 Types of skin cancer Basal Cell Carcinoma the least malignant and most common skin cancer Cancer lesions occur on sun-exposed areas of the face Appear as shiny, dome-shaped nodules that later develop a central ulcer with a pearly beaded edge. Slow growing 99% of cases are cured when lesion is removed surgically.
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- Squamous Cell Carcinoma Most often on the scalp, ears, hands, and lower lip Scaly, reddened, and round elevation that forms an ulcer w/ a raised border Grows rapidly and may spread to the lymph nodes if not removed. Also sun-induced Curable if treated early with surgery or radiation.
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- Malignant Melanoma Cancer of melanocytes Melanoma accounts for only 5% of skin cancers. However, its incidence is increasing rapidly and it is often deadly. Melanoma usually appears as a spreading brown to black patch that spreads rapidly to surrounding lymph nodes and blood vessels. The chance for survival is about 50%. Early detection helps to increase this chance.
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- Skin Cancer Detection ACS suggests that everyone examines skin for new moles/spots, especially people who are frequently exposed to the sun. ABCD rule for recognizing melanoma. Asymmetry two sides of mole do not match Border irregularity borders of the lesion are not smooth Color the spot contains areas of different colors Diameter the spot is larger than 6mm in diameter (pencil eraser) http://www.cancer.org/docroot/lrn/lrn_0.asp http://www.skincancer.org/