Integumentary-System.docx

 **Integumentary System** - SKIN OR INTEGRUMENT - Cutaneous Membrane - Epidermis - Dermis - Subcutaneous Membrane - Hypodermis (loose connective tissue)- not part of the skin or the integumentary system, but it does connect the skin to underlying muscle...

 **Integumentary System** - SKIN OR INTEGRUMENT - Cutaneous Membrane - Epidermis - Dermis - Subcutaneous Membrane - Hypodermis (loose connective tissue)- not part of the skin or the integumentary system, but it does connect the skin to underlying muscle or bone. - Accessory Organs - Hair - Glands - Nail **FUNCTIONS:** - **Protection**- The skin is the covering of the body. Though exposed to the external environment, the skin's structure reduces the negative and harmful effects of ultraviolet light. - **Sensation**- The integumentary system has sensory receptors that can detect heat, cold, touch, pressure, and pain. - **Temperature Regulation**- The skin plays a major role in regulating body temperature through the modulation of blood flow through the skin and the activity of sweat glands - **Vitamin D Production**- The skin produces a molecule that can be transformed into vitamin D, an important regulator of calcium homeostasis. - **Excretion**- Small amounts of waste products are excreted through the skin and glands. **EPIDERMIS** - not as thick as the dermis and contains no blood vessels. - Its living cells receive nutrients and excrete waste products by the diffusion of substances between the epidermis and the capillaries of the dermis - **Keratinocytes-** cells of the epidermis, produce a protein mixture called **keratin.** - **Other cells of the epidermis:** - **Melanocytes**- produce the pigment melanin, which contributes to skin color. - **Langerhans cells**- part of the immune system - **Merkel cells**- specialized epidermal cells associated with the nerve endings responsible for detecting light touch and superficial pressure. - **Keratinization-** Process in which Keratinocytes Change shapes and chemical composition - **Psoriasis**-Autoimmune disease where large scales of epidermal tissue are sloughed off **STRATA** - **Stratum Basale or Stratum germinativum**- The deepest portion of the epidermis is a single layer of cuboidal or columnar cells - **Stratum Spinosum**- Superficial to the stratum Basale **-** consisting of 8--10 layers of many-sided cells - **Stratum Granulosum**- consists of two to five layers of somewhat flattened, diamond-shaped cells. -This stratum derives its name from the presence of protein granules of **keratohyalin** - **Stratum Lucidum**- A thin, clear zone above the stratum granulosum \- It consists of several layers of dead cells with indistinct boundaries - **Stratum Corneum**- The last, and most superficial, stratum of the epidermis **-** composed of 25 or more layers of dead, overlapping squamous cells joined by desmosomes - **Cornified cells**- which are dead cells, with a hard protein envelope, filled with the protein keratin. Thick skin - has all five epithelial strata, and the stratum corneum has many layers of cells. - found in areas subject to pressure or friction, such as the palms of the hands, the soles of the feet, and the fingertips. **Thin Skin** - covers the rest of the body and is more flexible than thick skin. - Each of its strata contains fewer layers of cells than are found in thick skin; the stratum granulosum frequently consists of only one or two layers of cells, and the stratum lucidum is generally absent. **CALLUS-** forms when the stratum corneum of the epidermis increases in thickness. The increased number of cell layers provides added protection in the area that experiences more mechanical stress **CORN-** develop a cone-shaped structure \- The base of the cone is at the surface, but the apex extends deep into the epidermis, and pressure on the corn may be quite painful. **SKIN COLOR** - **Pigments** - **Melanin**- a group of pigments primarily responsible for skin, hair, and eye color. **-** produced by melanocytes - **Albinism-** usually a recessive genetic trait that results from an inability to produce tyrosinase. The result is a deficiency or an absence of pigment in the skin, the hair, and the irises of the eyes, **-**absence of melanin - **Tanning- Exposed to sunlight (increase production of melanin)** - **Mask of Pregnancy** - **Addison Disease-** endocrine disorder **-**Increase the production of melanin (bronze skin) - **Cyanosis-** turns skin to bluish color because of decrease in blood oxygen - **Carotene-** yellow-orange pigment found in plants (ex. Carrots and corn) - **Jaundice-** yellowish skin due to liver disorder (hyperbilirubinemia) **DERMIS** - The dermis is connective tissue - The cells of the dermis include fibroblasts, a few adipocytes, and macrophages. - **Collagen**- is the main type of protein fiber of the extracellular matrix, but elastic and reticular fibers are also present. **Contains** - **Blood Vessels**- allow for nutrient and waste exchange to the cells of the dermis and the living cells of the epidermis. - **Nerve endings**- varies in structure and function; include free nerve endings for pain, itch, tickle, and temperature sensations - **Hair follicles**- receptors for light touch - **Smooth muscles** - **Glands** - **Lymphatic vessels** **Other Receptors for Sensation** - **Pacinian corpuscles**- for deep pressure - **Meissner corpuscles**- r detecting simultaneous stimulation at two points on the skin - **Ruffini end organs**- sensing continuous touch or pressure **Composed of Two Tissue Layers** 1. **Papillary Layer**- superficial, have projections, called dermal papillae, that extend toward the epidermis. - loose connective tissue with thin fibers that are somewhat loosely arranged. - contains blood vessels that supply the overlying epidermis with oxygen and nutrients, remove waste products, and aid in regulating body temperature. - **Dermal Papillae**- under the thick skin of the palms of the hands and soles of the feet lie in parallel, curving ridges that shape the overlying epidermis into fingerprints and footprints. The ridges increase friction and improve the grip of the hands and feet 2. **Reticular Layer-** Deeper and main layer of dermis - composed of dense irregular connective tissue - continuous with the subcutaneous tissue and forms a mat of irregularly arranged fibers that are resistant to stretching in many directions. - **Elastic and Collagen** fibers are oriented more in some directions than in others and produce cleavage lines, or tension lines, in the skin - **Stretch Marks**- lines of scar tissue \- can develop on the abdomen and breasts of a woman during pregnancy or on the skin of athletes who have quickly increased muscle size by intense weight training. **SUBCUTANEOUS TISSUES** - a.k.a Hypodermis - attaches the skin to underlying bone and muscle and supplies the skin with blood vessels and nerves - consists of loose connective tissue with collagen and elastic fibers. - Main types of cells within the subcutaneous tissue are fibroblasts, adipocytes, and macrophages. - Where half the body's stored lipids are in the subcutaneous tissue, where they function in insulation and padding and as a source of energy. **INJECTIONS** - used to introduce certain substances, such as medication and vaccines, into the body. 4. **types** 1. **Intradermal Injection** - used for the tuberculin skin test, goes into the dermis. It is administered by drawing the skin taut and inserting a small needle at a shallow angle into the skin. 2. **Subcutaneous Injection** - extends into the subcutaneous tissue - achieved by pinching the skin to form a "tent," into which a short needle is inserted. 3. **Intramuscular Injection** - reaches a muscle deep to the subcutaneous tissue. - inserting a long needle at a 90-degree angle to the skin. 4. **Intravenous** - injection of a medication or another substance into a vein and directly into the bloodstream **Accessory Skin Structures** **Hair** - one of the characteristics of all mammals - dense and covers most of the body surface, it is called fur - **Lanugo-** fifth or sixth month of fetal development, delicate, unpigmented hair \- developed and covered the fetus - **Terminal hairs**- Near the time of birth, long, coarse, and pigmented hairs \- replace the lanugo of the scalp, eyelids, and eyebrows. - **Vellus hairs**- which are short, fine, and usually unpigmented, replace the lanugo on the rest of the body. \- At puberty, terminal hair, especially in the pubic and axillary regions, replaces much of the vellus hair. **Hair Structure** - **Shaft-** protrudes above the surface of the skin - **Root**- located below the surface \- The base of the root is expanded to form the **hair bulb** **Three concentric layers** 1. **Medulla** - central axis of the hair, and it consists of two or three layers of cells containing soft keratin 2. **Cortex** - surrounds the medulla and forms the bulk of the hair - cells of the cortex contain hard keratin 3. **Cuticle** - a single layer of cells also containing hard keratin. - edges of the cuticle cells overlap like shingles on a roof. **Hair Follicle** - a tubelike invagination of the epidermis that extends into the dermis. Consist 1. **Dermal root sheath** - portion of the dermis that surrounds the epithelial root sheath. 2. **Epithelial root sheath.** - has all the strata found in thin skin **Hair Growth** - Hair is produced in cycles that involve a growth stage and a resting stage. - Pattern Baldness- Kind of permanent loss - Hair follicles shrink and revert to producing vellus hair, which is very short, transparent, and for practical purposes invisible. - more common and more pronounced in certain men, it can also occur in women. - Genetic factors and the hormone testosterone are involved in causing pattern baldness. **Hair Color** - Similar to how melanocytes of the epidermis produce melanin and pass it to the keratinocytes of the skin, melanocytes within the hair bulb matrix produce melanin and pass it to keratinocytes in the hair cortex and medulla. 1. **Blonde hair** - little black-brown melanin, whereas jet-black hair has the most. Intermediate amounts of melanin account for different shades of brown. 2. **Red hair** - caused by varying amounts of a red type of melanin. 3. Gray hair - mixture of unfaded, faded, and white hairs. **Muscles** - **Arrector pili** - smooth muscle cells associated with each hair follicle - extend from the dermal root sheath of the hair follicle to the papillary layer of the dermis - Movement of the hair follicles produces raised areas called "goosebumps." **Glands** The major glands of the skin: sebaceous glands and the sweat glands - **Sebaceous Glands** - produce sebum - oily, white substance rich in lipids which released by the lysis and death of secretory cells, sebaceous glands are classified as holocrine glands - secretion of sebum onto the hair and surrounding skin prevents drying and protects against some bacteria. - **Sweat Glands** - two types: eccrine glands and apocrine glands - **Eccrine sweat glands**- most common type of sweat gland. -simple, coiled, tubular glands that open directly onto the surface of the skin through sweat pores - Sweat- hyposmotic fluid that leaves the duct of eccrine glands - **Apocrine sweat glands**- simple, coiled, tubular glands that usually open into hair follicles superficial to the opening of the sebaceous glands -found in the axillae and genitalia (scrotum and labia majora) and around the anus. -active at puberty as a result of sex hormones. -secretions contain organic substances, such as 3-methyl-2-hexenoic acid, that are essentially odorless when first released but are quickly metabolized by bacteria to cause what is commonly known as body odor **Other Glands** - **Ceruminous glands** - modified eccrine sweat glands located in the ear canal - **Cerumen**- composed of the combined secretions of ceruminous glands and sebaceous glands. - **Mammary glands** - modified apocrine sweat glands located in the breasts. **Nails** - thin plate consisting of layers of dead stratum corneum cells that contain a very hard type of keratin - located on the distal ends of the digits (fingers and toes). - Nails grow at an average rate of 0.5--1.2 mm per day, and fingernails grow more rapidly than toenails. - Y\] grow continuously throughout life and do not have a resting phase. **Consists** 1. **Proximal Nail root** 2. **Distal Nail body** **HARLEQUIN ICHTHYOSIS** **SKIN CANCER** - Most common type of cancer - results from damage caused by the ultraviolet (UV) radiation in sunlight. - induced by chemicals, x-rays, depression of the immune system, or inflammation, whereas others are inherited. - Fair-skinned individuals, who have less melanin, are at an increased risk of developing skin cancer compared with dark-skinned individuals, who have more melanin. 1. **Basal cell carcinoma-** most common type, - affects cells in the stratum basale. - removal or destruction of the tumor cures - varied appearance. - Some are open sores that bleed, ooze, or crust for several weeks. - Others are reddish patches; shiny, pearly, or translucent bumps; or scar-like areas of shiny, taut skin 2. **Squamous cell carcinoma-** second most common type of skin cancer. - affects cells in the stratum spinosum and - can appear as a wartlike growth; a persistent, scaly red patch; an open sore; or an elevated growth with a central depression. These lesions may bleed - removal or destruction of the tumor cures most cases. 3. **Melanoma-** least common, but most deadly, type of skin cancer, accounting for over 77% of the skin cancer deaths in the United States - they arise from melanocytes, most melanomas are black or brown, but occasionally a melanoma stops producing melanin and appears skin-colored, pink, red, or purple - 40% of melanomas develop in preexisting moles. - Treatment of melanomas when they are confined to the epidermis is almost always successful - invades the dermis and metastasizes to other parts of the body, it is difficult to treat and can be deadly **EARLY DETECTION OF MELANOMA** - routine examination of the skin and application of the ABCDE rule - A stand for asymmetry (one side of the lesion does not match the other side) - B is for border irregularity (the edges are ragged, notched, or blurred) - C is for color (pigmentation is not uniform) - D is for diameter (greater than 6 mm) - E is for evolving (lesion changes over time). **Burns** - injury to a tissue caused by heat, cold, friction, chemicals, electricity, or radiation - classified according to the extent of surface area involved and the depth of the burn Classified 1. **Partial thickness** - subdivided into first- and second-degree burns - **First-degree burns**- involve only the epidermis and may result in redness, pain, and slight edema - can be caused by sunburn or brief exposure to hot or cold objects, and they heal in a week or so without scarring. - **Second-degree burns**- damage the epidermis and dermis. Minimal dermal damage causes redness, pain, edema, and blisters. Healing takes approximately 2 weeks and no scarring results. 2. Full-thickness burns - also called third-degree burns. - epidermis and dermis are completely destroyed, and deeper tissue may be involved. - **Third-degree burns**- often surrounded by first- and second-degree burns. -usually painless because the sensory receptors have been destroyed. Third-degree burns appear white, tan, brown, black, or deep cherry-red. **Criteria to classify the seriousness of a burn** 1. **Major burn-** a third-degree burn over 10% or more of the BSA; a second-degree burn over 25% or more of the BSA; or a second- or third-degree burn of the hands, feet, face, genitals, or anal region 2. **Moderate burn-** a third-degree burn over 2--10% of the BSA or a second-degree burn over 15--25% of the BSA. 3. **Minor burn-** a third-degree burn over less than 2% or a second-degree burn over less than 15% of the BSA