MC1- Integumentary System PDF

INTEGUMENTARY SYSTEM DR. GASPAN | ANATOMY & PHYSIOLOGY - Week 3 SKIN The skin is made up of two major tissue layers: Topic Outline: F...

INTEGUMENTARY SYSTEM DR. GASPAN | ANATOMY & PHYSIOLOGY - Week 3 SKIN The skin is made up of two major tissue layers: Topic Outline: Functions of the Integumentary System 1. EPIDERMIS: is the most superficial layer of skin; It is Skin: Epidermis, Dermis & Skin Color a layer of epithelial tissue that rests on the dermis; Subcutaneous Tissue The epidermis provides protection. Accessory Skin Structures: Hair, Glands & Nails 2. DERMIS: is a layer of dense connective tissue; On Physiology of the Integumentary System: average the dermis is 10 to 20 times thicker than the Protection, Sensation, Vitamin D Production, epidermis; Responsible for most of the skin’s Temperature Regulation & Excretion structural strength. Integumentary System as a Diagnostic Aid Burns The skin rests on the subcutaneous tissue, which is also a layer of connective tissue. The subcutaneous tissue is not part of the skin, but it does connect the FUNCTIONS OF THE INTEGUMENTARY SYSTEM skin to underlying muscle or bone. The integumentary system consists of the skin and accessory structures, such as hair, glands, and nails. EPIDERMIS Integument means covering, and the integumentary The epidermis is stratified squamous epithelium; in system is one of the more familiar systems of the its deepest layers, new cells are produced by mitosis. body to everyone because it covers the outside of the The many cells of the epidermis prevent water loss body and is easily observed. and resist abrasion. The outermost cells protect the The appearance of the integumentary system can cells underneath, and the deeper, replicating cells indicate physiological imbalances in the body. replace cells lost from the surface. MAJOR FUNCTIONS OF INTEGUMENTARY SYSTEM During their movement, the cells change shape and 1. PROTECTION: The skin provides protection against chemical composition, a process called abrasion and ultraviolet light. It also prevents keratinization. The term keratinization reflects the microorganisms from entering the body and reduces fact that the cells become filled with the protein water loss, thus preventing dehydration. keratin which makes them more rigid and durable. 2. SENSATION: The integumentary system has sensory These characteristics are used to divide the epidermis receptors that can detect heat, cold, touch, pressure, into layers called strata; layers. From the deepest to and pain. the most superficial, the five strata are the 3. VITAMIN D PRODUCTION: When exposed to 1. Strata basale ultraviolet light, the skin produces a molecule that can 2. Stratum spinosum be transformed into vitamin D, an important regulator 3. Stratum granulosum of calcium homeostasis. 4. Stratum lucidum 4. TEMPERATURE REGULATION: The amount of 5. Stratum corneum blood flow beneath the skin’s surface and the activity 5 STRATA of sweat glands in the skin both help regulate body 1. Stratum basale: a base consists of cuboidal or temperature. columnar cells that undergo mitotic divisions about 5. EXCRETION: Small amounts of waste products are every 19 days. One daughter cell becomes a new lost through the skin and in gland secretions. PIQUE| 1  stratum basale cell and can divide again. The other daughter cell is pushed toward the surface, a journey that takes about 40–56 days. As cells move to the surface, changes in the cells produce intermediate strata 2. Stratum spinosum: take on a flattened appearance and accumulate lipid-filled vesicles called lamellar bodies. 3. Stratum granulosum: are flat and diamond shaped. 4. Stratum lucidum: is a thin, clear zone between the stratum granulosum and stratum corneum. The cells of this stratum no longer have nuclei or organelles, and as a result, the cells stain more lightly. Skin is classified as thick or thin based on the structure of the epidermis. Stretch Marks Thick skin has all five strata and is found in If the skin is overstretched for any reason, the dermis areas subject to pressure or friction, such as can be damaged. the palms of the hands, the soles of the feet, Develop when a person increases in size quite and the fingertips. rapidly. Thin skin lacks the stratum lucidum and Dermal Papillae covers the rest of the body. The terms thick Contain many blood vessels skin and thin skin only refer to the number of Blood flow through these vessels supplies the epidermal strata and not to the overall overlying epidermis with nutrients, removes waste thickness of the skin, which is determined by products, and helps regulate body temperature. the dermis. The dermal papillae in palms, feet, and digit tips form 5. Stratum corneum: is the most superficial stratum of parallel, curving ridges that shape the overlying the epidermis. It consists of dead squamous cells epidermis into fingerprints and footprints called filled with keratin. Keratin gives the stratum corneum friction ridges. its structural strength. The stratum corneum cells are TYPES OF INJECTION also coated and surrounded by lipids released from 1. INTRADERMAL INJECTION - delivers material to the the lamellar bodies of the skin cells. These lipids act blood slowly and is administered by drawing the skin as waterproofing material, thereby preventing fluid taut and inserting a small needle at a shallow angle loss through the skin. The stratum corneum is into the dermis; an example is the tuberculin skin test. composed of 25 or more layers of dead squamous 2. SUBCUTANEOUS INJECTION - achieved by cells joined by desmosomes. Eventually, the pinching the skin to form a “tent” and inserting a short desmosomes break apart, and the cells are sloughed needle into the adipose tissue of the subcutaneous from the skin. Excessive sloughing of stratum tissue; an example is an insulin injection. corneum cells from the surface of the scalp is called 3. INTRAMUSCULAR INJECTION - delivers material to dandruff. In skin subjected to friction, the number of the blood faster than intradermal or subcutaneous layers in the stratum corneum greatly increases, injections. An intramuscular injection is accomplished producing a thickened area called a callus/ hard by inserting a long needle at a 90-degree angle to the skin. Over a bony prominence, the stratum corneum skin into a muscle deep to the subcutaneous tissue. can thicken to form a cone-shaped structure called a Intramuscular injections are used for most vaccines corn. and certain antibiotics. DERMIS The dermis is composed of dense collagenous connective tissue containing fibroblasts, adipocytes, and macrophages. The dermis is dense connective tissue Collagen and elastic fibers are responsible for the strength of the dermis. The collagen fibers of the dermis are oriented in many different directions and can resist stretch. Cleavage Lines/ Tension Lines the orientation of the collagen fibers. An incision made across the cleavage lines is likely to gap and produce considerable scar tissue, but an incision made parallel with the lines tends to gap less and produce less scar tissue  SKIN COLOR Metastasis is common, and unless diagnosed and Several factors determine skin color: (1) pigments in treated early in development, this cancer is often fatal the skin, (2) blood circulating through the skin, and (3) the thickness of the stratum corneum. MELANIN Group of pigments primarily responsible for skin, hair, and eye color. Most melanin molecules are brown to black pigments, but some are yellowish or reddish. Provides protection against ultraviolet light from the sun. Produced by melanocytes MELANOCYTES are irregularly shaped cells with many long processes that extend between the epithelial cell of the deep part Estrogen and melanocyte-stimulating hormone, cause of the epidermis. an increase in melanin production during pregnancy Produce melanin, which is responsible for different in the mother, darkening the nipples, the pigmented skin colors. circular areas around the nipples, and the genitalia MELANOSOMES even more. The cheekbones and forehead can also which move into the cell process of the melanocytes. darken, resulting in “the mask of pregnancy.” Also, a Are produced by the golgi apparatus of the dark line of pigmentation can appear on the midline of melanocytes the abdomen. Move into the melanocyte cell process. Blood flowing through the skin imparts a reddish hue, ALBINISM and when blood flow increases, red color intensifies a recessive genetic trait that causes a deficiency or CYANOSES an absence of melanin. A decrease in blood O2 content produces a bluish Albinos have fair skin, white hair, and unpigmented color in the skin irises in the eyes. BIRTHMARKS SKIN CANCER congenital (present at birth) disorders of the blood Is the most common type of cancer. vessels in the dermis. Mainly caused by UV light exposure CAROTENE Most skin cancer develops on the face, neck, or A yellow pigment found in plants such as squash and hands. carrots. Fair-skinned people more prone or older than 50 Use as a source of Vitamin A Prevented by limiting sun exposure and using Is lipid-soluble, and when consumed it accumulates in sunscreens the lipids of the stratum corneum and in the UVA rays cause tan and is associated with malignant adipocytes of the dermis and subcutaneous tissue. melanomas SUBCUTANEOUS TISSUE UVB rays cause sunburns Also known as hypodermis (under the dermis) 3 MAIN TYPES OF SKIN CANCER Not part of the skin but instead attaches the skin to 1. BASAL CELL CARCINOMA underlying bone and muscle and supplies it with blood Most frequent type, begins with cells in stratum vessels and nerves basale and extends into the dermis to produce an It loose connective tissue, including adipose tissue open ulcer. that contains about half the body’s stored lipids Surgical removal or radiation therapy cures this type Adipose tissue in subcutaneous tissue functions as of cancer. padding and insulation Little danger that this will spread, or metastasize, to Can be used to estimate total fat other areas of the body. Acceptable percentage of body fat varies from 21% to 2. SQUAMOUS CELL CARCINOMA 30% for females and from 13% to 25% for males. Develops from cells immediately superficial to the ACCESSORY SKIN STRUCTURES stratum basale. Accessory structures of the skin are attached to or Typical result is a nodular, keratinized tumor confined embedded into the skin. The accessory skin to the epidermis. If untreated the tumor can invade structures are hair, glands, and nails. the dermis, metastasize and cause death. HAIR 3. MALIGNANT MELANOMA Found everywhere on the skin, except on the palms, A rare form of skin cancer that arises from soles, lips, nipples, parts of the genitalia, and the melanocytes, usually in a preexisting mole. distal segments of the fingers and toes. A mole is an aggregation, or “nest”, of melanocytes. Melanoma can appear as a large, flat, spreading lesion or as a deeply pigmented nodule.  HAIR PAPILLA Where hair is produced in the hair bulb, that rests on the hair papilla. Hair papilla is an extension of the dermis that protrudes into the hair bulb. Blood vessels within the papilla supply the hair bulb with the nourishment needed to produce the hair. GLANDS GLANDS Organ that makes one or more substances, such as hormones, digestive juices, sweat, tears, saliva, or milk. Hair is produced in cycles, with a growth stage and resting stage. During the growth stage, hair is formed by mitosis of epithelial cells within the hair bulb; these cells divide and undergo keratinization 2 MAJOR GLANDS OF THE SKIN During the resting stage, growth stops and the hair is 1. SEBACEOUS GLANDS held in the hair follicle. Are simple, branched acinar glands The duration of each stage depends on the individual Most being connected by a duct to the hair superficial part of a hair follicle Eyelashes grow for about 30 days and rest for 105 They produced sebum, an oily, white days, whereas scalp hairs grow for 3 years and rest 1 substance rich in lipids. Sebum is released to 2 years. by holocrine secretion and lubricates the hair COMPONENTS OF HAIR and the surface of the skin, which prevents HAIR FOLLICLE drying and protects against some bacteria. An invagination of the epidermis that extends deep 2. SWEAT GLANDS into the dermis are small tubular structures of the skin that Composed of epithelial tissue, hair follicles can play produce sweat. an important role in repair for the skin occur all over the body, but are most Associated with each hair follicle are smooth muscle numerous on the forehead, the armpits, the cells called the arrector (that which raises) pili (hair) palms and the soles of the feet. Contraction of the arrector pili causes the hair to Its main function is to control body become more perpendicular to the skin’s surface, or temperature to “stand on end,” and it produces a raised area of 2 KINDS OF SWEAT GLANDS skin called a “goose bump.” 1. ECCRINE SWEAT GLANDS HAIR SHAFT Are simple, coiled, tubular glands and protrudes above the surface of the skin; the root is release sweat by merocrine secretion. below the surface Located in almost every part of the skin but HAIR BULB most numerous in the palms and soles. Is the expanded base of the root. They produce a secretion that is mostly Responsible for hair growth water with salt HARD CORTEX Have ducts that open onto the surface of the Which surrounds a softer center, the medulla. skin through sweat pores. Emotional Cortex is covered by the cuticle (skin), a single layer sweating can also occur in the palms, soles, of overlapping cells that holds the hair in the hair armpits, and other places. follicle 2. APOCRINE SWEAT GLANDS  Are simple, coiled, tubular glands that 2.Acts as a barrier that prevents microorganisms and produce a thick secretion rich in organic and other foreign substances from entering the body cools the body. 3. The stratified squamous epithelium of the skin Released primarily by merocrine secretion, protects underlying structures against abrasion through some glands demonstrate holocrine 4. Melanin absorbs ultraviolet light and protects secretion. underlying structures from its damaging effects The glands open into hair follicles in the 5. Hair provides protection in several ways: The hair on armpits and genitals the head acts as a heat insulator, eyebrows keep Apocrine sweat glands become active at sweat out of the eyes, eyelashes protect the eyes puberty because of the influence of sex from foreign objects, and hair in the nose and ears hormones. prevents the entry of dust and other materials. Secretion generally is odorless, but when 6. The nails protect the ends of the fingers and toes from released quickly breaks down by bacterial damage action giving the body odor. SENSATION NAILS Many sensory receptors are associated with the skin. is a thin plate, consisting of layers of dead stratum Receptors in the epidermis and dermis can detect corneum cells that contain a very hard type of keratin. pain, heat, cold, and pressure Although hair does not The nail also attaches to the underlying nail bed, have a nerve supply, sensory receptors around the which is located distal to the nail matrix. hair follicle can detect the movement of a hair. Cell production within the nail matrix causes the nail VITAMIN D PRODUCTION to grow. Unlike hair, nails grow continuously and do When the skin is exposed to ultraviolet light, a not have a resting stage precursor molecule of vitamin D is formed. COMPONENTS OF NAILS UV light causes the skin to produce a precursor 1. NAIL BODY molecule of Vitamin D. The visible part of the nail, and the part of The precursor molecule is carried by the blood to the the nail covered by skin is the nail root. liver where it is enzymatically converted. 2. CUTICLE The enzymatically converted molecule is carried by Or eponychium, is a stratum corneum that the blood to the kidneys where it is converted again to extends onto the nail body and the nail root the active form of vitamin D. extends distally from the nail matrix. Vitamin D stimulates the small intestine to absorb 3. NAIL BED calcium and phosphate for many body functions. the area beneath the nail plate between the TEMPERATURE REGULATION lunula and the hyponychium. Body temperature normally is maintained at about epithelial tissue with a stratum basale that 37°C (98.6°F). gives rise to the cells that form the nail. Regulation of body temperature is important because 4. LUNULA the rate of chemical reactions within the body can be small part of the nail matrix increased or decreased by changes in body can be seen through the nail body as a temperature. whitish, crescent-shaped area at the base of slight changes in temperature can make enzymes the nail. operate less efficiently and disrupt the normal rates of 5. NAIL MATRIX chemical changes in the body The nail matrix and bed are epithelial tissue Exercise, fever, and an increase in environmental with a stratum basale that gives rise to the temperature tend to raise body temperature. cells that form the nail. In order to maintain homeostasis, the body must rid The nail matrix is thicker than the nail bed itself of excess heat. and produces most of the nail. PHYSIOLOGY OF THE INTEGUMENTARY SYSTEM PROTECTION The integumentary system performs many protective functions: 1. The intact skin plays an important role in reduction in body water loss Explain why placing an ice pack on the skin results in that They can be caused by sunburn or area of the skin appearing red. brief exposure to very hot or very 1. Blood vessels in the dermis dilate and enable more cold objects, and they heal without blood to flow within the skin, thus transferring heat scarring in about a week from deeper tissues to the skin. b. Second-degree burn 2. The excess heat is lost by radiation (infrared energy), s damage both the epidermis and convection (air movement), or conduction (direct the dermis. contact with an object). Excess heat is also released If dermal damage is minimal, as sweat spreads over the surface of the skin and symptoms include redness, pain, evaporates, thus reducing body temperature. edema, and blisters. 3. Heat can be conserved by the constriction of dermal Healing takes about 2 weeks, and blood vessels, which reduces blood flow to the skin. no scarring results. 4. Thus, less heat is transferred from deeper structures If the burn goes deep into the to the skin, and heat loss is reduced dermis, the wound appears red, When we are exposed to cold environments, blood tan, or white; can take several vessels in the dermis constrict and smaller amounts months to heal; and might scar. of warm blood flow through the skin, causing a FULL-THICKNESS BURN, or THIRD-DEGREE BURN decrease in skin temperature. If the skin temperature The epidermis and the dermis are completely drops below about 15°C (59°F), dermal blood vessels destroyed, and recovery occurs from the edges of the dilate. burn wound. EXCRETION Often are surrounded by areas of first- and The integumentary system plays a minor role in second-degree burns. excretion The first- and second-degree burn areas are painful, Excretion the removal of waste products from the the region of third-degree burn is usually painless body. because sensory receptors in the epidermis and water and salts, sweat contains small amounts of dermis have been destroyed. waste products, such as urea, uric acid, and Third-degree burns appear white, tan, brown, black, ammonia. or deep cherry red Even though the body can lose large amounts of FOURTH-DEGREE BURN sweat, the sweat glands do not play a significant role Extremely severe burns that affect tissues deeper in the excretion of waste products than the subcutaneous tissue. INTEGUMENTARY SYSTEM AS A DIAGNOSTIC AID These burns often damage muscle, bone, and other The integumentary system is useful in diagnosis tissues associated with them. because it is observed easily Like third-degree burns, fourth-degree burns are CYANOSIS painless due to the destruction of the pain receptors. a bluish color to the skin caused by decreased blood Deep partial-thickness and full-thickness burns take a O2 content, is an indication of impaired circulatory or long time to heal, and they form scar tissue with respiratory function. disfiguring and debilitating wound contracture JAUNDICE A yellowish skin color can occur when the liver is damaged by a disease, such as viral hepatitis. Rashes and lesions in the skin can be symptoms of problems elsewhere in the body. BURN is injury to a tissue caused by heat, cold, friction, chemicals, electricity, or radiation. CLASSIFICATION OF BURN ACCORDING TO DEPTH PARTIAL-THICKNESS BURN Part of the stratum basale remains viable, and regeneration of the epidermis occurs from within the burn area, as well as from the edges of the burn. Partial-thickness burns are divided into first- and second-degree burns: a. First-degree burn involve only the epidermis and are red and painful. Slight edema, or swelling, may be present.  BURN HEALING In all second-degree burns, the epidermis, including the stratum basale where the stem cells are fund, is damaged The epidermis regenerates from epithelial tissue in hair follicles and sweat glands, as well as from the edges of the wound Deep partial-thickness burns and full-thickness burns take a long time to heal, and they form scar tissue with disfiguring and debilitating wound contractures. TREATMENT OF BURNS To prevent complications of deep partial-thickness and full-thickness burns and to speed healing, skin grafts are often performed. In a procedure called a split skin graft, the epidermis and part of the dermis are removed from another part of the body and placed over the burn When it is not possible or practical to move skin from one part of the body to a burn site, physicians sometimes use artificial skin or grafts from human cadavers. AGING AND THE INTEGUMENT Blood flow decreases and skin becomes thinner due to decreased amounts of collagen Decreased activity of sebaceous and sweat glands make temperature regulation more difficult Loss of elastic fibers causes the skin to sag and wrinkle.