Topic 3

Second-degree burns

involve damage to both the epidermis and the upper portion of the underlying dermis. Characterized by blisters, fluid-filled pockets that form between the epidermal and dermal layers.

hypodermis

layer beneath the dermis or subcutaneous tissue, which serves as a storage repository for fat.

merkel cells

located in the stratum basale, function as touch receptors. These cells form junctions with sensory nerve endings that relay information about touch to the brain.

Dermis

or "true skin", is located directly beneath the epidermis and is made of both areolar and dense irregular connective tissue composed of collagen and elastic fibers. The collagen fibers provide toughness and also bind with water molecules to help keep skin moist. The elastic fibers are what keep skin looking young, without wrinkles or sagging. The dermis consists of two layers: -Papillary dermis-Reticular dermis The dermis has a rich supply of blood vessels which dilate or constrict to help dissipate or retain body heat, respectively. -Also present throughout the dermis are a variety of specialized sensory receptors for touch, vibration, pain ,and temperature. -The outer or upper layer of the dermis is called the papillary dermis, after the dermal papillae, uneven fingerlike projections that protrude from its surface into the epidermis. Some of the dermal papillae contain capillaries that supply nutrients to the epidermis. Other dermal papillae contain nerve endings involved in sensing touch and pain. (Meissner's corpuscles are the sensory receptors that relay touch) -These papillae form genetically determined, ridged patterns on the palms of the hands, fingers, toes, and soles of the feet. It is from the papillae patterns on the fingers that each person's unique fingerprints are derived. -Notice: The up and down boarder between the dermis and the epidermis helps bond the layers together. -Underneath the papillary layer lies the deepest layer of the skin; the reticular dermis. As shown in the picture below, the collagen and elastic fibers in this region have an irregular arrangement. The reticular layer includes blood and lymphatic vessels, sweat and oil glands, involuntary muscles, hair follicles, and nerve endings. Pressure receptors called pacinian corpuscles.

Debridement

removal of dead skin using surgical or chemical procedures. Maggot therapy is popular-they eat away dead skin.

Third-degree burns

the most serious type of skin burn because they destroy the entire thickness of the skin; also called full-thickness burns. Appears greyish-white or blackened. The nerve endings have been destroyed, later scarring and pain will occur.

Apocrine Glands

which begin to function during puberty, are located in the axilla and genital regions. They are larger than the eccrine glands and secrete a opaque fluid consisting of sweat, fatty acids, and proteins. The function of these exocrine glands is unknown. Unlike the eccrine gland ducts, the aprocrine gland ducts empty into hair follicles.

bruises

-Black and blue marks revealing sites where blood has escaped from circulation and has clotted in the tissue spaces. Clotted blood masses are called hematomas. -An unusual tendency to bruise may indicate a Vitamin C deficiency in the diet or hemophilia (bleeder's disease).

Nails

-Underlying each nail is a specialized region of the stratum basale known as the nail bed. The proximal end of the nail bed is a thickened region called the nail matrix, or growth zone. As with hair, it is within the matrix that nail growth occurs, with cells rapidly becoming keratinized and dying. -Nails are transparent, but appear pinkish in color because of the capillary supply beneath the stratum basale. The exception to this transparence is the white, crescent-moon shaped region at the base of the nail, which is positioned over the thickened nail matrix, is called lunula. -Each nail has a free edge, extending from the nail plate or nail body (visible attached portion), and a root (embedded in the skin). The borders of the nail are overlapped by skin folds, called nail folds. The thick proximal nail is called the cuticle.

Nerve Injury or Pressure

A common cause of skin numbness is an injury or pressure to a nerve. A neck injury, for example, can cause the skin along the arm or hand to feel numb, while a lower back trauma can cause the numbness to go down the back of the leg.

Toenail Fungus (Tinea unguium) (Fungal)

A fungal infection under the nails of the fingers and/or toes. It causes discoloration and thickening of the infected nail. Treatment: OTC creams generally do not help this condition; a prescription antifungal medication must be taken orally for several weeks.

Necrotizing fasciitis (Bacterial)

A very severe and usually deadly form of necrotizing soft tissue infection due to Streptococcus pyogenes, which is sometimes called "flesh-eating bacteria." It can destroy the muscles, skin, and underlying tissue. Necrotizing soft tissue infection develops when the bacteria enters the body, usually through a minor cut or scrape. The bacteria begins to grow and release harmful substances (toxins) that kill tissue and affect blood flow to the area. As the tissue dies, the bacteria enters the blood and rapidly spreads throughout the body.

Psoriasis

Common skin disorder that involves redness and irritation. Characterized by regions of thick, red skin with flaky, silver-white patches called scales that itch, burn, crack, and sometimes bleed. The exact cause is unknown, but research suggests it may be a hereditary autoimmune condition which causes overproduction of skin cells. It is not contagious. Often triggered or exacerbated by bacterial or viral infections, minor injuries to the skin, dry skin, too little or too much sunlight, excessive alcohol consumption, stress, and certain medications. Goal of treatment is to control symptoms and prevent infection. Three treatment approaches are available: Topical treatment, systemic treatment, and light therapy (phototherapy)

Decubitus Ulcers

Also known as pressure ulcers or bedsores, are skin injuries caused by an area of localized pressure that restricts blood flow to one or more areas of the body. Without normal blood supply to provide O2 and nutrients, the skin cells die. They can occur anywhere on the body; but most form over bony areas such as the lower back, coccyx (tailbone), hips, elbows, and ankles. They begin as areas of reddened skin, but as the cells start to die, small cracks or openings in the skin appear. As the condition progresses, the tissue continues to degenerate and an open ulcer forms. If not treated, tissue degeneration progresses all the way to the bone and can eventually be fatal. Treatment includes prescription of oral antibiotics to address/prevent infection and removal of damaged/dead tissue. Dead tissue must be removed, as it prevents healing. Two approaches to removing damaged/dead tissues: -Debridement-Vacuum-assisted closure

Impetigo (Bacterial)

An acute, superficial skin infection due to a highly contagious bacteria, staphylococcus. It is common on the face, around the mouth and nose in children ages 2-5. It presents as pink, water-filled raised lesions that develop a golden-yellow crust and eventually rupture.

Albinism

An inherited condition that prevents the normal production of melanin. Albinism produces very little pigment in the skin, hair, and eyes. Individuals with albinism have extremely pale skin and white hair.

Homeostatic Imbalances of Skin

As the first "line of defense" in protecting the body from the external environment, the skin is routinely subject to minor injuries and is exposed to a variety of common infections. -The skin can develop over 1000 different ailments -Skin commonly sustains minor cuts, abrasions, and blisters that tend to heal quickly due to the regenerative properties of epithelial tissue -With all minor skin injuries, infection is a major concern. Injuries that penetrate the underlying tissues are more complicated, and infection is still the most significant concern. -Common disorders result from allergies, bacterial, viral or fungal infections. -Less common, but far more damaging, are burns and skin cancers

Cancers of the Skin

Basal cell carcinoma, Squamous cell carcinoma, Malignant melanoma Many skin conditions involve bumps or small non-cancerous lesions. Common warts are an example. Thus far we have discussed conditions that are benign-that is, they involve tumors that do not metastasize, or spread, to remote regions of the body. When a tumor is malignant, or cancerous, it tends to metastasize to other parts of the body. Skin cancer is the most common cancer in the US; overexposure of the sun is a major risk factor.

Boils and Carbuncles (Bacterial)

Boils and carbuncles are painful, pus-filled bumps that form under your skin when bacteria (Staph) infect and inflame one or more of your hair follicles and sebaceous glands. Boils (furuncles) usually start as red, tender lumps. The lumps quickly fill with pus, growing larger and more painful until they rupture and drain. A carbuncle is a cluster of boils that form a connected area of infection under the skin.

Burns

Burns are injuries that can arise from exposure to excessive heat, corrosive chemicals, electricity, or UV rays. Burns, which vary considerably in severity, cause tissue damage and cell death. When severely damaged nearly every organ system suffers; metabolism may accelerate or become impaired, changes in immune system occur, and cardiovascular system may falter. -Why is a burn dangerous?- Cells are destroyed and precious fluids can seep out, dehydration and electrolyte imbalance can lead to shutdown of kidneys and circulatory shock (low blood pressure due to low blood volume) -The volume of fluid lost can be estimated indirectly by determining how much of the body surface is burned (extent of burns), using the rule of nines. -Method divides body into 11 areas, each accounting for 9% of the total body surface area, plus an additional area surrounding the genitals (the perineum) representing 1% of body surface area. -Infection becomes the most important threat and is the leading cause of death. Burned skin is sterile for about 24 hours, after that, pathogens such as bacteria and fungi invade destroyed areas and multiply rapidly. The patient's immune system becomes depressed within one to two days of a severe burn.

Temperature regulation

Capillaries dilate to dissipate heat and constrict to conserve heat. Sweat evaporation provides a cooling effect.

Squamous Cell Carcinoma

Caused by overproduction of cells in the stratum spinosum layer of the epidermis. Grows rapidly and metastasizes to adjacent lymph nodes if not removed. Lesions appear scaly, reddened papule (small, rounded elevation) that progress to an ulcer-like mass with a firm, raised border. Most common locations: --Fair-skin: scalp, ears, lower lip, and posterior portion of hands --Dark-skin: typically develop this condition in areas not exposed to the sun, such as legs and feet.

Cellulitis (Bacterial)

Cellulitis is a common, potentially serious bacterial (Staph) skin infection. Cellulitis appears as a swollen, red area of skin that feels hot and tender, and it may spread rapidly. Skin on lower legs is most commonly affected, though cellulitis can occur anywhere on your body or face. Cellulitis may affect only your skin's surface or tissues underlying your skin and can spread to your lymph nodes and bloodstream. Left untreated, the spreading infection may rapidly turn life-threatening.

Herpes varicella (Chickenpox) (Viral)

Chickenpox generally presents with a low-grade fever and a rash. Because it is highly contagious, it tends to spread quickly and widely The fluid filled blisters are very itchy and can spread all over the body or be limited in scope. The rash is firstly papular then becomes vesicular (blistered) and progresses to crusted lesions or ulcerations over about five days. This disease is rarely fatal. Vaccine is available

Cutaneous Glands

Cutaneous glands are glands of the skin. They are all exocrine glands that release their secretions to the skin surface via ducts. They fall into two groups: sebaceous glands and sweat glands. As these glands are formed by the cells of the stratum basale, they push into the deeper skin regions and ultimately reside almost entirely in the dermis.

Skin Color

Different color melanosomes, genetics, and the environment contribute to individual skin color. *This is also true for your eyes. Is also influenced by emotional stimuli, and alterations in skin color may indicate certain conditions.

Ringworm (Tinea corporis) (Fungal)

Does not actually involve any type of worm; the characteristically red, ring-shaped rash with a pale center somewhat resembles the shape of a worm. It is caused by prolong sweating and poor hygiene (it is especially common in children). Ringworm is highly contagious and can be spread through direct contact with infected skin on someone's body or through contaminated areas such as pool surfaces. Treatment: Keeping the skin clean and dry and applying a topical OTC antifungal cream

Eczema (Atopic dermatitis)

Due to a hypersensitivity reaction (similar to an allergy), leading to long-term swelling and redness of the skin. Almost always itchy; not contagious --Atopic dermatitis is most common in infants. It may start as early as age 2 to 6 months. Many people outgrow it by early adulthood. It is not caused by allergies. The condition tends to get worse when the person is exposed to certain triggers. Allergies to pollen, mold, dust mites, or animals -Cold and dry air in the winter -Colds or the flu -Contact with irritants and chemicals

Epithelial Body Membranes

Epithelial membranes provide a lining, or covering, for the internal and external surfaces of the body. These membranes include both a sheet of epithelial cells and an underlying layer of connective tissue.

Herpes simplex virus type 2 (HSV-2) (Viral)

Genital form of herpes. Repeat outbreaks are common, particularly during the first year of infection. As with all herpes, once a person has been infected, it remains dormant, with potential to reactivate at any time. It is uncommon for HSV-2 to be found around the mouth, but it is becoming more common to find HSV-1 in the genital area. Both types are sometimes passed to other areas of the body through skin-to-skin contact.

Peritonitis

Peritonitis is inflammation of the peritoneum, a serous membrane that lines your inner abdominal wall and covers the organs within your abdomen. Peritonitis can result from any rupture (perforation) in your abdomen, or as a complication of other medical conditions. Signs and symptoms of peritonitis include: Abdominal pain or tenderness, bloating or a feeling of fullness (distention) in your abdomen, fever, nausea and vomiting, shortness of breath, rapid heartbeat, decreased urine and stool output. Peritonitis requires prompt medical attention to fight the infection. Treatment usually involves antibiotics and, in some cases, surgery. Left untreated, peritonitis can lead to severe, potentially life-threatening infection throughout your body.

Hair

Hair follicles are bulb-shaped, flexible epithelial structure within the dermis that produce hair. The base of the follicle is "invaded" by a papilla of connective tissue containing a rich capillary supply, which provides nourishment for hair cell formation. -In the matrix, or growth zone, within the base of the follicle are specialized cells that divide and generate living hair cells. Like epithelial cells generated in the stratum basale, these cells are pushed up toward the scalp, they become filled with keratin and die. Most of the hair shaft is, therefore, nonliving material composed mainly of protein. -Each hair consists of a central core called the medulla surrounded by a bulky cortex layer. The cortex is enclosed by an outermost cuticle formed by a single layer of cells that overlap one another. The cuticle is the most heavily keratinized region, providing strength. -The part of the hair enclosed in the follicle wall is called the root. The part projecting from the surface if the scalp or skin is called the hair shaft.

Herpes (Viral)

Herpes is a viral infection that produces small, painful, blister-like sores. Once a herpes infection is present, it lasts for the rest of a person's life. Herpes can remain dormant, with no noticeable signs of infection. However, flare-ups occur; the resurgence of symptoms is usually accompanied by periods of stress or sickness Several different varieties of the herpes virus are known to exist. We will discuss: -Herpes varicella -Herpes zoster -Herpes simplex virus type 1 (HSV-1) -Herpes simplex virus type 2 (HSV-2)

Sebaceous Glands

If a sebaceous gland's duct becomes blocked by sebum, a whitehead appears on the skin surface. If the accumulated material oxidizes and dries, it darkens, forming a blackhead. Acne is an active infection of the sebaceous glands accompanied by "pimples" on the skin. Acne can be mild or extremely severe, leading to permanent scarring. Seborrhea "cradle cap"-in infants is caused by over active sebaceous glands.

Diabetes

Individuals may experience diabetic neuropathies in which diabetics suffer nerve damage throughout the body. Neuropathy is more common in those with issues controlling their blood sugar levels due to high levels of body fat

Pleurisy or Pleuritis

Inflammation of the pleura, the membrane that lines the lungs and thoracic cavity. The serosal membrane is a double-layered membrane. The double-layered pleura protects and lubricates the surface of the lungs as they inflate and deflate within the rib cage. Normally, a thin, fluid-filled gap - the pleural cavity- allows the two layers of the pleural membrane to slide gently past each other. When these layers become inflamed, with every breath, sneeze, or cough, their roughened surfaces rub painfully together like two pieces of sandpaper.

Contact dermatitis

Itching, redness, and swelling of the skin which may progress to blistering Caused by exposure of the skin to chemicals (ex. those in poison ivy) that provoke allergic responses in sensitive individuals.

Water barrier

Keratin and oils in the skin reduce water loss through evaporation and form a barrier against water infusion.

Marfan Syndrome

Marfan syndrome is a genetic disorder that affects the body's connective tissue. Connective tissue holds all the body's cells, organs and tissue together. It also plays an important role in helping the body grow and develop properly. Marfan syndrome is caused by a defect (or mutation) in the gene that tells the body how to make a specific protein. This mutation results in an increase in a protein causes problems in connective tissues throughout the body. Features of the disorder are most often found in the heart, blood vessels, bones, joints, and eyes. Some Marfan features - for example, aortic enlargement (expansion of the main blood vessel that carries blood away from the heart to the rest of the body) - can be life-threatening. The lungs, skin and nervous system may also be affected. Marfan syndrome does not affect intelligence.

Jock Itch (Tinea cruris) (Fungal)

Primarily affects males around the groin region. It is caused by a combination of prolonged sweating and friction from clothes. It can be spread through direct contact with infected skin or unwashed clothing. Treatment: Keeping the skin clean and dry, wearing loose clothing, and applying a topical antifungal.

Melanin

Melanin is a pigment, made by melanocytes, which ranges in color from reddish yellow to brown and black; it is primarily responsible for human skin color. These cells are located in the stratum basale; the area responsible for phagocytizing skin pigment -Exposure to sunlight causes melanocytes to produce more melanin. As melanin granules are pushed out into neighboring skin cells, the result is tanning. -As the pigment accumulates within the cells, the melanin forms a protective "umbrella" over the superficial side of their nuclei, which shields the cell's DNA from the damaging effects of UV radiation. -The presence of extra melanin in the skin functions as a sunscreen. -Moles and freckles are the result of high concentrations of melanin. -Despite melanin's protective effects, excessive sun exposure eventually damages skin. -Causes elastic and collagen fibers to clump, producing "leathery" skin. -Depresses the immune system. -Overexposure can alter DNA. (Remember: Cells with DNA mutations can become cancerous)

Lack of Blood

Mild cases of skin numbness generally occur due to a lack of blood supply to a region of the body. For example, remaining the in the same seated or standing position can cause poor blood circulation, leading to the numbing sensation

Malignant Melanoma

Most serious form of skin cancer; cancer of melanocytes. Melanoma can begin wherever there is pigment; most appear spontaneously, but some develop from pigmented moles. Typically dark colored and irregular in shape. It can also appear pink, red, or "fleshy". Metastasizes rapidly to surrounding lymph and blood vessels.

Stratum Spinosum, stratum Granulosum

Moving up through the stratum spinosum and stratum granulosum, cells become progressively flatter and increasingly full of keratin, which makes them tough and water resistant.

Mucous Membranes

Mucous membranes (Mucosa) line the body cavities and canals that open to the outside of the body. -These cavities include all the hollow organs of the respiratory, digestive, urinary, and reproductive tracts. -The mouth, nose, lungs, GI tract and bladder are examples of hollow organs lined with mucous membranes. Structure: consists of epithelial cells, their basement membrane, and a thick layer of loose connective tissue called the lamina propria. -Lamina propria is a constituent of the most lining (mucous membrane), which lines various tubes in the body. -The term mucosa always refers to the combination of the epithelium plus the lamina propria. All mucous membranes are "wet" or moist: the membranes of the digestive and respiratory tract secrete mucus. -Mucus is a slippery solution that protects the mucous membranes and aids in transporting substances.

Causes of Skin Numbness

Numbness and tingling can occur anywhere in the body, but they are most often felt on skin of the fingers, hands, feet, arms and legs. Numbness is decreased or lost sensation. There are several causes of this condition, many of which are mild but can also indicate a serious underlying health problem.

Herpes simplex virus type 1 (HSV-1) (Viral)

Often associated with the common cold, generating "cold sores" or "fever blisters" around the mouth. The virus localizes in a cutaneous nerve, where it remains dormant until activated by emotional stress, fever, or UV radiation. Small fluid-filled blisters that itch and sting usually occur around the lips and in the oral mucosa. -Most people get HSV-1 (herpes simplex type 1) as an infant or child. This virus can be spread by skin-to-skin contact with an adult who carries the virus. An adult does not have to have sores to spread the virus. Both forms of HSV (type 1 and 2) are highly contagious and can be transmitted to the mouth or genital area.

Herpes zoster-Shingles (Viral)

Once a person infected with chickenpox has recovered, the virus remains inactive (dormant) in certain nerves in the body. In an adult, the virus can recur as herpes zoster, commonly known as shingles. -The reason the virus suddenly becomes active again is not clear. Often only one attack occurs. -In the U.S., ~50% of people older than 80 years of age have had shingles at least once. -Vaccine is available and recommended for adults 60 and older Shingles involves an extremely painful, blistering skin rash accompanied by headache, fever, or a general feeling of unwellness. It may trigger more serious symptoms, such as chronic nerve pain.

Connective Tissue Membrane

Only one type of membrane in the body is composed solely of connective tissue and includes no epithelial cells: synovial membrane. They also line tendon sheaths (the connective tissue that surrounds tendons) as well as bursae, the small connective tissue sacs that serves as cushions for tendons and ligaments surrounding the joints. -They secrete synovial fluid, which provides cushioning and reduces friction and wear on moving structures.

Sensory perception

Receptor cells transmit nerve signals that contain information about the environment, including touch, pressure, vibration, pain, and temperature to the CNS.

Redness, or erythema

Reddened skin may indicate embarrassment (blushing), fever, hypertension, inflammation, or allergy.

Sebaceous (Oil) Glands

Sebaceous gland are located all over the body, except for the palms of the hands and soles of the feet. Most oil glands empty into a hair follicle. They produce an oily substance called sebum. Sebum keeps skin soft and contains acidic compounds that kill bacteria.

Serous Membranes

Serous membranes (Serosa): Serous membranes line cavities that do not open to the exterior, such as the pericardial, pleural, and peritoneal cavities. The names of the serous membranes depend on their locations: -Pleura (encloses lungs) -Pericardium (surrounds the heart) -Peritoneum (lines the abdominal cavity and covers its organs) Structure: consist of three components: a layer of simple squamous epithelium called mesothelium, the basement membrane, and a layer of loose connective tissue (usually areolar). Serous membranes line cavities that do not open to the exterior, such as the pericardial, pleural, and peritoneal cavities. Each serous membrane forms a double lining (inner and outer lining) -The outer layer of each body cavity is called the parietal layer. (lines the walls of the cavities) -The inner lining that covers each organ within a body cavity (closes "wrapping" organs) is called the visceral layer. -They are separated by a thin film (secreted by the membranes) called serous fluid. Serous fluid serves as a lubricant between the parietal and visceral membranes to minimize friction and "wear and tear" on organs that move within the linings, such as the beating heart. -The serous fluid acts as a lubricant to reduce friction between organs that shift and move as they perform bodily functions. -Epithelial cells are responsible for secreting small quantities of this slippery serous fluid that accumulates in the space between the layers.

Sweat Glands

Sudoriferous (Sweat) glands, are distributed in the dermis over the entire body, with a larger concentrations in the axilla, on the palms of the hands, soles of the feet, and on the forehead. Controlled by nervous system. Each person has approximately 2-3 million. Two types of sweat glands: Eccrine glands Apocrine glands

Vitamin D production

Sunlight converts modified cholesterol molecules to vitamin D, which is essential for bone health.

Body Membranes

The body membranes surround and help protect the body's surfaces. These surfaces include: -Cavities that open to the outside world -Internal cavities that house body organs -Capsules that surround ball-and-socket synovial joints -Skin It is important to have a clear understanding of the similarities and differences of the membranes that cover these different body surfaces. Cover surfaces, line body cavities, and form protective (and often lubricating) sheets around organs. They fall into two broad categories. Epithelial membranes categories include:-Mucous membranes (lining respiratory, digestive, reproductive and other body tracts)-Serous membranes (lining the ventral body cavities)-Cutaneous membranes (Skin) Connective Tissue Membranes:-Synovial membranes (lining joint capsules)

Decubitus ulcers

The dermis has an abundant supply of blood vessels; any restriction of the normal blood supply to the skin results in cell death and, if severe or prolonged, skin ulcers. Decubitus ulcers (bedsores) form as a result of restricted blood flow to specific areas of the body.

When is a burn critical?

The following criteria deem a patient to be considered "critically burned" 1) Over 25% of body has second-degree burns 2) Over 10% of body has third-degree burns. 3) Any third-degree burns of the face, hands, or feet.

Stratum Basale

The innermost layer, the stratum basale, absorbs nutrients from the adjacent, underlying dermis. The cells in this layer are constantly undergoing cell division/producing new skin cells: -As new cells germinate, they are pushed toward the surface and away from the nutrients and eventually die.

Basal Cell Carcinoma

The most common form of skin cancer and fortunately, the least malignant. It is caused by overproduction of the cells in the stratum basale, that push upward, forming dome-shaped bumps. Lesions appear as shiny, dome-shaped nodules that later develop a central ulcer with a pearl-like edge. Most commonly affected areasareas of the face that have been exposed to the sun.

Athlete's Foot (Tinea pedis) (Fungal)

The most common fungal infection causing itchy, red, cracked or peeling skin condition between the toes or on the side of the foot. It is highly contagious as it spreads rapidly on locker room and shower floors. Treatment: keeping feet clean and dry, especially between the toes, and using an OTC anti-fungal powder or cream.

Stratum Corneum

The outer layer of the epidermis, consists of dead cells that are completely filled with keratin and are continually shedding.

Functions of the Integumentary System

The skin forms a protective cover that serves a variety of functions. -Skin acts as the first line of defense in protecting the underlying tissues. -Skin is critically important in regulating body temperature. -The skins outermost layer contains keratin, a tough protein, also found in hair and nails that adds structural strength. -Keratin also helps protect the skin against damage from harmful chemicals. -It also serves as a water barrier --The skin is pliable, yet tough, which allows it to take constant punishment from external agents. Without our skin, we would fall quickly to bacteria and perish from water and heat loss. Skin is also involved in certain chemical processes in the body. -Specialized cells in the skin called melanocytes produce melanin, a pigment that protects the body against harmful effects of UV ray damage from sunlight. -Exposure to the UVB rays from sunlight causes the conversion of modified cholesterol molecules (called provitamin D3) in the skin to vitamin D. -Vitamin D is essential for bone health. -Sweating eliminates chemical waste products from the body -Such as urea, uric acid and salts. Because the fluid secreted is acidic, it helps to protect the body against bacteria infections. Skin contains specialized cutaneous sensory receptors that are part of the nervous system. They transmit nerve signals that contain information about the environment, including touch, pressure, vibrations, pain and temperature.

Anatomy of the Skin

The skin has two layers: An outer layer called the epidermis and directly beneath is the dermis: epidermis and the dermis The epidermis and dermis are firmly connected. Recall which areas of your skin were thick and which were thin?

Mucus Membrane

This is a low power view of the junction between the esophagus on the left and the stomach on the right. The transition in the surface epithelium is marked by the arrowhead. Note the submucosal mucous glands in this distal portion of the esophagus that terminate, roughly, where the stomach begins.

Protection

Tough keratin protects against mechanical injury and chemical damage. Melanocytes produce melanin to protect against UV ray damage. Acidic sweat protects against bacterial infections.

Pallor, or blanching

Under certain types of emotional stress (ex. Fear and anger), some people become pale. Pale skin can also indicate anemia, low blood pressure, or impaired blood flow into an area.

Waste elimination

Urea and uric acid are eliminated in sweat.

Human Papillomavirus (HPV) (Viral)

Warts are raised, typically painless growths on the skin that vary in shape and size. They can be spread from one part of the body to another. All types of warts are caused by the human papillomavirus (HPV). HPV's are a group of more than 150 related viruses. Common warts typically appear on the hands or fingers and tend to disappear without treatment. It is important, to make sure that a wart-like growth on an adult is not a form of skin cancer. Planter warts, which develop on the soles of the foot, grow inward and can be very painful. When warranted, warts can be removed by surgery, cryotherapy (freezing), and topical medications, such as salicylic acids. Genital warts caused by HPV infections are the most common STI in the US. Over 40 of the HPVs can be easily spread through direct, skin-to-skin contact. More than 50% of all sexually active people are infected with HPV at some point in their life. HPV infections cause nearly all cervical cancers. There are two major categories of HPVs: low risk and high risk. High risk HPVs account for about 5% of all cancers.

Cyanosis

When hemoglobin is poorly oxygenated, both the blood and skin appear blue, a condition called cyanosis. -Common during a heart failure or breathing disorders. -In individuals with lots of pigmentation, the skin may not appear cyanotic because of the masking effects of melanin, but it is usually apparent in mucus membranes and nail beds.

stratum lucidum

a clear layer of thick skin found only on the palms of hands, fingers, soles of feet, and toes.

Vacuum-assisted closure

a vacuum tube is attached to the wound. It draws out moisture from the ulcer, thereby shortening the healing process and reducing risk of infection.

jaundice

a yellow cast is an abnormal yellow skin tone, usually signifies a liver disorder where excess bile pigments are absorbed into the blood, circulated throughout the body, and deposited in body tissues.

First-degree burns

affect only the epidermal layer; involve reddening of skin and mild pain. They tend to heal in less than a week. Most types of sunburns are first-degree burns.

Hypodermis

also known as subcutaneous tissue includes dense connective tissue and adipose tissue. It is within the hypodermis that fat cells reside. Some amount of body fat is important for padding the insulating the interior of the body. Fat also serves as a energy source.

Cutaneous Membranes

also known as the skin; they are the only epithelial membrane that is exposed to air and is a dry membrane. -Even though it contains sweat glands -Its superficial epidermis is composed of a keratinizing stratified squamous epithelium. -The underlying dermis is made up areolar loose and irregular dense connective tissue.

Eccrine Glands

are the major sweat glands of the body. They cover most of the body and open directly onto the skin. The sweat secreted is a clear, acidic fluid that consists of ~99% water, but also contains waste products such as urea, uric acid, salts, and vitamin C. Main role thermoregulation; sweat glands contain nerve endings that cause sweat to form when the body temperature is elevated or external temperature is elevated.

epidermis

composed of 5 layers of stratified squamous epithelium capable of keratinizing (becoming hard and tough). The outer layer of skin, the epidermis is composed of 5 layers of tissue: From the inside out (old cells to young cells) (superficial to deep):-Stratum corneum-Stratum lucidum-Stratum granulosum-Stratum spinosum-Stratum basale The epidermis completely replaces itself (every 25-45 days) via cellular division, which occurs in the stratum basale. All epidermal layers consist of cells, but they do not include a blood supply that provides nutrients to the skin. Most cells within the epidermis are keratinocytes, which produce keratin (tough fibers which make skin tough but pliable) -Keratin allows this layer to provide us with a durable "overcoat" for the body, which protects deeper cells from the hostile external environment (air) and from water loss and helps the body resist biological, chemical, and physical assaults. -The epidermis contains specialized cells associated with the immune and nervous systems. -Epidermal (Langerhans) dendritic cells respond to the presence of foreign bacteria or viruses by initiating an immune system response, which brings in other specialized cells to attack the foreign invaders. There are as many as 800 dendritic cells per square millimeter of skin to help ward off infections. The epidermis completely replaces itself (every 25-45 days) via cellular division, which occurs in the stratum basale.

dermis

composed of connective tissue, which connects it to the epidermis.

Synovial membranes

consist of modified connective tissue and line joint cavities, such as those found in the knee. Synovial membranes do not contain epithelial tissue.

Burn Classification

first degree burns second degree burns third degree burns