Chapter 5 - Integumentary System

Nail functions

1) Protect distal end of digits 2) Provide support and counterpressure to the palmar surfaces of fingers to enhance touch perception and manipulation 3) Allow us to grasp and manipulate small objects, and can be used to scratch and groom the body in various ways

Papillary region of the dermis

1/5 of thickness of the dermis; thin collagen and elastic fibers; dermal papillae (small nipple shaped structures that project into the undersurface of the epidermis) increase surface area, contain capillary loops (blood vessels) and some contain meissner corpuscles (nerve endings sensitive to touch), free nerve endings, dendrites that lack any apparent structural specialization - sensations of warmth, pain, coolness, tickling and itching; epidermal ridges; increase surface contact between epidermis and dermis an important source of nutrition from the blood vessels for the overlying epidermis; molecules diffuse into the dermal papillae to the cells of the stratum basale allowing basale stem cells to divide and the keratinocytes to grow and develop; fit together with epidermal ridge to form strong junction that resists great force

Development of nails

10 weeks, consist of a thick layer of epithelium called primary nail field that is keratinized epithelium and grows distally from the base. Nine months nails reach tips of digits

Stratum corneum

25-30 layers of flattened dead keratinocytes; thin cells, flat, plasma membrane enclosed packages of keratin that no longer contain a nucleus or any internal organelles; final product of differentiation process of keratinocytes; cells overlap like scales on a snake; neighboring cells form strong connections with eachother; plasma membranes of adjacent cells fit together like pieces of a jig saw puzzle; cells are shed and replaced continuously by deeper strata; protects deeper layers from injury and microbial invasion

Dermis

2nd deeper part of the skin; dense irregular connective tissue containing collagen and elastic fibers; tensile strength; stretch and recoil easily; thicker than epidermis; cells present are fibroblasts, some macrophages, few adipocytes near boundary of the subcutaneous layer; blood vessels, nerves, glands, hair follicles (epithelial invagination of epidermis) are embedded in the dermal layer; essential to survival of the epidermis. Two layers: Thin superficial papillary region and the thick deeper reticular region;

Suderiferous Glands

3 to 4 million sweat glands; release sweat or persperation into hair follicles, or skin surface through pores. Divided into two main types eccrine and apocrine

Epidermal ridges

3rd month of fetal development straight lines, patterns of loops and whorls as seen on the palms, fingers, soles and toes are downward projections of the epidermis into the dermis between the dermal papillae of the papillary region; strong bond between the epidermis and dermis in regions of high mechanical stress; increase surface area and increasing the grip of the hand by friction and increased amount of meissner corpuscles increasing tactile sensitivity

Stratum lucidum

4-6 layers of flattened clear, dead keratinocytes that contain large amounts of keratin and thickened plasma membranes; found on palms, soles of feet, fingertips

Hair

Also called pili, found on most skin surfaces except for palms of hands and soles and plantar surfaces of the feet. In adults hair is mostly found on the scalp, eyebrows, external genetalia and axillae; genetic influences hair growth; guards scalp from injury and UV rays and heat loss; eyebrows and lashes protect the eyes from foreign particles; function in sensing touch by reacting to a hair moving slightly

Stratum basale

Also known as Stratum germinativum. Deepest layer of epidermis; single layer of cuboidal or columnar keratinocytes; has stem cells (undergo cell division to continually produce keratinocytes); large nuclei; ribosomes in cytoplasm; small Golgi complex; few mitochondria; rough endoplasmic reticulum. Keratin intermediate filaments (tonofilaments) makes up the cytoskeleton within keratinocytes. Keratin intermediate filaments attach to desmosomes that bind cells to eachother and cells of adjacent stratum spinosum, and hemidesmisomes. Hemidesmisomes bind keratinocytes to basement membrane that is between the epidermis and dermis. Melanocytes and merkel discs scattered among keratinocytes of basal layer.

Cutaneous Sensations

Arise from the skin, including tactile sensations: touch, pressure, vibrations and tickling, thermal sensations such as warmth and coolness, pain from tissue damage. Nerve endings and receptors distributed throughout the skin, including tactile discs of the epidermis, corpuscles of touch in the dermis, hair root plexuses around each hair follicle.

Reticular region of the dermis

Attached to subcutaneous layer, bundles of thick collagen fibers, wandering macrophages and other floating cells, fibroblasts; some adipose cells in the deepest layers; coarse elastic fibers; collagen fibers form a weave network that is more regular than the papillary region (helps resist skin stretching); blood vessels, nerves, sebaceous (oil) glands, suderiferous (sweat) glands occupy spaces between fibers; combination of collagen and elastic fibers provide the skin strength, extensibility, elasticity

Melanin

Causes skin color to be pale yellow to reddish brown to black. Two forms of melanin: Pheomelanin (yellow to red - very little melanin in the epidermis, red color associated with hemoglobin and amount of blood supply to the tissues) and eumelanin (brown to black - large amounts of melanin in the epidermis) most apparent in hair. Melanocytes produce melanin and are most plentiful around the areolae (nipples), face, legs, arms, penis, mucous membranes. Number of melanocytes same in most people, differences in skin color due to the amount of pigment that accumulates in the keratinocytes; can accumulate in patches called freckles or have a benign overgrowth called a nevus or mole; or flat blemishes called age (liver) spots caused by sun exposure and usually appears after 40 years of age. Absorbs UV radiation, prevents damage to DNA in epidermal cells, neutralizes free radicals from UV damage; protective function; Vitamin D synthesis from small UV light exposure

Keratinization

Cells move from one epidermal layer to another they accumulate more keratin

Hair color

Color of hair due to the type and amount of melanin present; melanin synthesized by melanocytes scattered in matrix of bulb, passes through the cortex and medulla of hair; eumelanin (brown to black); pheomelanin (yellow to red); gray because of progressive decline in melanin; white from no melanin and air bubbles in the shaft

Anatomy of hair

Composed of dead keratinized columnar cells bound together by extracellular proteins. Shaft (superficial portion of hair, and projects above surface of skin); root (portion deep to shaft, penetrates the dermis and sometimes into subcutaneous layer). Shaft and root consist of three layers: medulla, cortex and cuticle. Inner medulla (two to three rows of irregularly shaped cells that contain large amounts of pigment granules in dark hair, small amounts of pigment granules in gray hair and no pigment granules in white hair); middle cortex (elongated cells making up the major part of the shaft); cuticle (outermost layer and has a single layer of thin, flat cells arranged in shingles with free edges pointing toward the end of the hair); hair follicle (surrounds the root made of the external sheath and an internal root sheath referred to as epithelial root sheath), external root sheath (downward continuation of the epidermis), internal root sheath (produced by the matrix and forms a cellular tubular sheath of epithelium between the external root sheath and the hair); Dermal root sheath (dense dermis that surrounds the hair follicle). Bulb (an onion shaped structure that surrounds the dermal root sheath and the each hair follicle); papilla (a nipple-shaped indentation that contains aereolar connective tissue, many blood vessels that nourish growing hair follicle); hair matrix (germinal layer of cells that arise from the stratum basale (the site of cell division); Sebaceous oil glands and smooth muscle cells (arrector pili extend from superficial dermis of the skin to the dermal root sheath around the side of the hair follicle - autonomic nerve endings stimulate the arrector pili muscles and make the hairs stand on end); hair root plexus (dendrites of neurons that generate nerve impulses when the hair shafts are moved)

Epidermis

Composed of keratinized stratified squamous epithelium; four cells keratinocytes (90%) arranged in 4-5 layers and produce keratin, melanocytes (8%), langherhans cells, merkel cells;

Integumentary System

Composed of skin, hair, oil and sweat glands, nails, and sensory receptors. Maintains body temperature, protects the body, provides sensory information regarding surrounding environment.

Skin

Cutaneous membrane; covers external surface of body; largest organ and covers approximately 22 meters (22 square feet) and weighs 4.5-5kg about 7% of total body weight; thickness range from 0.5mm on eyelids to 4.0mm on heels, most of body 1-2mm. Two main parts: Epidermis - superficial, thinner portion of epithelial tissue; avascular Dermis - deeper, thicker portion of connective tissue; vascular

Subcutaneous Layer

Deep to Dermis; not considered part of the skin layer; also called Hypodermis; contains areolar and adipose tissue; fibers from the dermis anchor skin to the subcutaneous layer then to the fascia that surrounds muscles and bones; storage depot for fat and contains large blood vessels that supply the skin; contain nerve endings called pacian (lamellated) corpuscles that are sensitive to pressure.

Development of integumentary dermis skin

Dermis arises from mesoderm, located deep to the surface of the ectoderm. Mesenchyme derives from mesoderm and is a loose embryonic connective tissue. Mesenchymal cells differentiate into fibroblasts and begin to form collagen and elastic fibers by the 11th week; dermal papillae, (form capillary loops, corpuscles of touch and free nerve endings) are formed as the epidermal ridges form and parts of the superficial dermis project into the epidermis. 12th week hair follicles develop as down growths of the basal layer of the epidermis into the deeper dermis called hair buds, as hair buds dig deeper into the dermis the distal ends are called hair bulbs, papillae of the hair are invaginations of the hair bulbs and fill with mesoderm in which blood vessels and nerve endings develop; matrix is formed from the hairs in the center of the hair bulb which forms the hair, peripheral cells of the hair bulb form the epithelial root sheath, mesenchyme in the surrounding dermis develop into dermal root sheath and arrector pili muscle. Fifth month produce lanugo, and is shed prior to birth.

Blood reservoir

Dermis houses blood vessels that carry 8-10% of the total blood flow in a resting adult

Melanocytes

Develop from ectoderm of developing embryo and produces pigment melanin. Long slender projection that extend between keratinocytes and transfer granules to them

Sebaceous Oil Glands

Distribution: Largely in lips, glans penis,labia minora, tarsal glands; small in trunk and limbs; absent in palms and soles Location of secretory portion: Dermis Termination of excretory duct: Mostly connected to hair follicles Secretion: Sebum (mixture of triglycerides, cholesterol, proteins and inorganic salts) Functions: Prevent hairs from drying out, prevent water loss from skin, keep the skin soft, inhibit growth of some bacteria Onset of function: relatively inactive during childhood; activated during puberty

Thin skin

Distribution: all parts of body except areas such as palms and soles, surface of digits Epidermal thickness: 0.10-0.15 mm (0.004-0.006 in) Epidermal strata: stratum lucidum is lacking; thinner strata spinosum and corneum Epidermal ridges: lacking due to poorly developed, fewer, and less organized dermal papilae Hair follicles and arrector pili muscles: present Sebaceous glands: present Sudoriferous glands: fewer Sensor receptors: sparse

Thick skin

Distribution: areas such as palms, palmar surfaces of digits, and soles Epidermal thickness: 0.6 - 4.5mm (0.024 - 0.18 in), due to mostly a thicker stratum corneum Epidermal strata: stratum lucidum present; thicker strata spinosum and corneum Epidermal ridges: present due to well-developed and more numerous dermal papillae organized in parallel rows Hair follicles and arrector pili muscles: absent Sebaceous glands: absent Sudoriferous glands: more numerous Sensory receptors: denser

Ceruminous glands

Distribution: external auditory canal Location of secretory portion: subcutaneous layer Termination of excretory duct: surface of external auditory canal or into ducts of sebaceous glands Secretion: cerumen, a waxy material Function: impede entrance of foreign material and insects into external ear canal, waterproof canal, prevent microbes from entering cells Onset of function: soon after birth

Apocrine sweat glands

Distribution: skin of axillae, groin, araolar, bearded regions of face, clitoris, labia minora Location of secretory portion: mostly in deep dermis and upper subcutaneous layer Termination of excretory duct: hair follicle Secretion: perspiration consists of water, ions of Na+ and Cl-, urea, uric acid, ammonia, glucose, lactic acid, amino acids Functions: stimulated during emotional stress and sexual excitement Onset of function: puberty

Eccrine sweat glands

Distribution: throughout skin of most regions of body, especially skin of forehead, palms and soles Location of secretory portion: mostly in deep dermis (sometimes in upper subcutaneous layer) Termination of excretory duct; surface of epidermis Secretion: perspiration consisting of water, ions Na+ and Cl-, urea, uric acid, ammonia, amino acids, glucose, lactic acid Functions: regulation of body temperature, waste removal, stimulated during emotional stress Onset of function: soon after birth

Fingerprints

Ducts of sweat glands open on tops of the epidermal ridges as sweat pores causing prints that are left on a surface

Langerhans cells

Epidermal dentritic cells arise from red bone marrow and migrate to epidermis, constitute a fraction of the epidermal cells and contact the Merkel (tactile) disc (detect touch sensations)

Epidermal Wound Healing

Epidermal wound may extend only to the dermis, edges of the wound usually involve only slight damage to superficial epidermal cells. Abrasion, minor burns, portion of skin has been scraped away. Basal cells of the epidermis surround the wound, break contact with basement membrane, cells enlarge and migrate across the wound, cells appear to migrate as a sheet until advancing cells from opposite sides of the wound meet; cells encounter each other they stop migrating due to a cellular response called contact inhibition. Epidermal growth factor stimulates basal stem cells to divide and replace the ones that have moved into the wound, relocated basal epidermal cells divide to build new strata, thus thickening the new epidermis

Develeopment of integumentary epidermal skin

Epidermis derived from ectoderm, which covers the surface of the embryo. Fourth week only single layer of ectodermal cells; seventh week, single layer called the basal layer divides and forms a superficial protected layer of flattened cells called periderm, peridermal cells are continously sloughed off; fifth month, secretion from sebaceous glands mix with the sloughed off periderm and hairs to form a fatty substance called vernix caseosa, vernix caseosa covers and protects the skin of the fetus from constant exoosure to amniotic fluid, facilitates child birth because it is slippery and protects skin from being damaged by nails; 11 weeks the basal layer forms an intermediate layer of cells, proliferation of basal cells eventually forms all layers of peidermis, epidermal ridges form along epidermal layers, cells from ectoderm migrate into the dermis and differenticate into melanoblasts, they enter into dermis and differentiate into melanocytes. Langerhans cells arise from red bone marrow invade epidermis. Merkel cells appear in the epidermis in the fourth to sixth months

Dandruff

Excessive amount of keratinized cells shed from the scalp

Excretion and absorption

Excretion: elimination of substances from the body 400ml of water evaporates daily through the skin, excretion of small amounts of salts, carbon dioxide, two organic minerals resulting from the breakdown of proteins ammonia and urea. Absorption: passage of materials from the external environment into body cells. Certain lipid molecules such as fat soluble vitamins (A, D, E and K), certain drugs, oxygen and carbon dioxide, toxic materials such as acetone, carbon tetrachloride, salts of heavy metals such as lead, mercury, and arsenic, substances in poison ivy and poison oak. Cortisone is lipid soluble and moves easily through the papillary region of the dermis, its anti-inflammatory properties inhibit histamine production by mast cells (histamine contributes to inflammation)

Scar tissue formation

Fibrosis (process of scar tissue formation), Hypertrophic scar (elevated above normal em\oidermal surface), Keloid scar (scar extends beyond boundaries into normal surrounding tissues, also called cheloid scar) Differs from normal tissue because collagen fibers are more densely arranged, decreases elasticity and fewer blood vessels, less number of hairs, skin glands or sensory structures as undamaged skin, scars are lighter in color due to collagen fibers and scarcity of blood vessels.

Development of Sebaceous oil glands and Sudoriferous sweat glands

Four months it develops as outgrowths from the side of hair follicles and remain connected to follicles. Five months Sweat glands form from downgrowths (buds) of stratum basale of the epidermis into the dermis, buds penetrate into the dermis the proximal portion forms the duct of sweat gland and distal portion coils and forms the secretory portion of the gland, appear of soles and palms and a little later on other areas of the body

Hair growth

Growth stage (cells of hair matrix divide and push the existing hair upward thus making it longer, while cells are being pushed upward from the base of the hair the cells keratinize and die, takes 2-6 years); regression stage (cells of hair matrix stop dividing, hair follicle atrophies, hair stops growing, takes 2-3 weeks); resting stage takes 3 months. Normal hair loss in adults is 70-100 hairs per day, may be accelerated by illness, stress, chemotherapy, four months after childbirth, rapid weight loss diets, age, genetics, radiation therapy. Alopecia (partial or complete lack of hair, result from genetic factors, aging, endocrine disorders, chemotherapy, skin disease

Types of hairs

Hair follicles develop after 12 weeks of fertilization, fifth week of development hairs grow lanugo (fine non pigmented, downy hairs) that covers body of fetus; terminal hairs (heavily pigmented, long, course) replace the lanugo hair of the eyebrows, eyelashes and scalp; vellus hairs (peach fuzz, short, fine, pale hairs, barely visible to the naked eye) replace the lanugo hair on the body; Vellus hairs are replaced in puberty from hormones in the armpits, genitals and face, arms, chest and legs in men.

Contribution of the Integumentary system for the Respiratory System

Hair in the nose trap particles from entering the airway; sensory perception on skin may adjust breathing rate

Accessory structures of the skin

Hair, skin, nails, glands develop from embryonic epidermis

Thermoregulation

Homeostatic regulation of body temperature; liberates sweat at its surface by adjusting the flow of the blood in the dermis, sweat produced from eccrine sweat glands increases, vaporization of sweat from skin helps cool the body; blood vessels in skin dilate which increases the amount of heat loss from the body. Low temperature production of sweat from eccrine sweat glands are decreased; skeletal muscle contractions stimulate body heat; blood vessels constrict to reduce heat loss

Epidermal growth factor

Hormone like protein that regulates the growth of the epidermis

Callus

Increased cell and keratin production caused from friction to the skin, resulting in abnormal thickening of the stratum corneum

Body Piercing

Insertion of jewelry through an artificial opening.

Protection

Keratin protects underlying tissues from microbes, abrasion, heat and chemicals, resist invasion by microbes; lipids released by lamellar granules inhibit evaporation of water from skin surface and stop the entry of water during swimming and showering; oily sebum from sebaceous glands keeps skin and hairs from drying out and contains bactericidal chemicals; acidic pH of perspiration stops growth of some microbes; pigment melanin helps shield against damaging UV rays; two types of cells carry out protective functions are epidermal langerhans cells that warn the immune system of invasion of potentially harmful microbial invaders by recognizing and processing them and macrophages in the dermis phagocytize bacteria and viruses that bypass the langerhans cells of the epidermis.

Growth of epidermis

Keratinization occurs; cells go through apoptosis; keratin cells sloughed off replaced by underlying cells becoming keratinized (takes 4-6 weeks for cells to form in stratum basale, rise to surface, become keratinized and get sloughed off); nutrients and oxygen diffuse to avascular epidermis from blood vessels in the dermis; stratum basale is closest to the blood vessels and receive most of the nutrients and oxygen and are most metabolically active and constantly undergo cell division; epidermal strata above the basale receives fewer nutrients and the cells eventually die and slough off; the more the cells are sloughed off the higher the cell division in the stratum basale; epidermal growth factor plays a role in regulating growth of the cells.

Contribution of the Integumentary system for the Endocrine system

Keratinocytes in the skin help activate Vitamin D to calcitriol, a hormone that aids absorption of dietary calcium and phosphorous

Contribution of the Integumentary system on the Urinary system

Kidney cells receive partially activated vitamin d from the skin and convert it to calcitriol; some waste products are excreted from sweat, contributing to the excretion by the urinary system

Dermatology

Medical specialty that deals with integumentary skin disorders

Structural basis of skin color

Melanin, carotene and hemoglobin account for varying skin pigments in the skin

Stratum granulosum

Middle layer of epidermis; consists of 3-5 layers of flattened keratinocytes that are undergoing apoptosis (orderly, genetically programmed cell death where the nucleus fragments before the cell dies); cells, nuclei and organelles begin to degenerate as it moves farther away from its source of nutrition from the dermal blood vessels; keratin intermediate cells are more prominent due to the regression of the organelles in the cell; darkly staining granules of protein called keratohyalin (assembles keratin intermediate filaments into keratin); keratinocytes have lamellar granules that fuse with the plasma membrane and releases a lipid rich secretion (deposited in cells of the stratum granulosum, stratum corneum and stratum lucidum; acts a water repellent sealant reducing loss and entry of water and foreign particles). As nuclei of the keratinocytes break down during apoptosis the cells die, thus marking the transition between the deeper, metabolically active strata and the dead cells of the more superficial strata.

Ceruminous glands

Modified sweat glands in external ear that secretes a wax lubricator; secretory portion lies in subcutaneous layer deep to sebaceous glands; excretory ducts open directly onto the surface of the external auditory canal (ear canal) or into ducts of sebaceous glands; cerumen is secreted (mixture of ceruminous and sebaceous secretions); protect ears together with the hairs in the external auditory canal against foreign bodies and insects, waterproofs canal and prevents bacteria and fungi from entering cells

Contribution of Integumentary system on the Reproductive system

Nerve ending in skin and subcutaneous tissue respond to sexual stimuli; suckling of baby stimulates milk ejection; mammary glands produce milk (modified sweat glands), skin stretches during pregnancy

Deep wound healing

Occurs when injury extends to dermis and subcutaneous layer, multiple tissue layers required, healing process is more complex than epidermal wound healing. Scar tissue is formed, tissue loses some of its normal function. Four phases: inflammatory phase, migratory phase, proliferative phase, maturation phase. Inflammatory phase: blood clot forms in the wound and loosely unites the round edges; inflammation a vascular and cellular response that helps eliminate microbes, foreign material and dying tissue in prepiration for repair, vasodilation and increased permeability of blood vessels associated with inflammation enhance delivery of helpful cells, these include phagocytic white blood cells called neutrophils, monocytes which develop into macrophages that phagocytize microbes and mesenchymal cells that develop from fibroblasts Migratory phase: clot becomes a scab, epithelial cells migrate beneath the scab to bridge the wound, fibroblasts migrate along fibrin threads and begin synthesizing scar tissue (collagen fibers and glycoproteins and damages blood vessels begin to regrow, granulation tissue filles the wound Proliferative phase: extensive growth of epithelial cells beneath the scab, deposition by fibroblasts of collagen fibers in random patterns, continued growth of blood vessels. Maturation phase, scab sloughs off once the epidermis has been restored to normal thickness, collagen fibers become more organized, fibroblasts decrease in number and blood vessels are restored to normal

Sebaceous Glands

Oil glands; simple branched acinar (rounded) glands; connected to hair follicles; secreting portion lies in the dermis and usually opens to neck of hair follicle; lips, glans penis, labia minora and tarsal glands of the eyelids open directly onto the surface of skin; absent in palms and soles of feet; small in most areas of trunk and limbs; large in skin of breasts, face, neck, and superior chest; secrete oily substance called sebum (mixture of triglycerides, cholesterol, proteins, and inorganic salts), coats surface of hair keeping them moist and not brittle, prevents excessive evaporation of water through the skin, keeps the skin soft and pliable, inhibits the growth of some bacteria

Hypoxia

Oxygen deficiency at the tissue level

Tattooing

Permanent coloration to the skin by applying a needle with ink into the dermis. Originated in Egypt between 4,000 and 2,000 BC.

Nails

Plates of tightly packed, hard, dead, keratinized epidermal cells that form clear, solid covering over the dorsal surfaces of the distal portions of the digits. Nail body (visible portion of the nail, flattened keratinized cells, pink portion from blood flowing through capilleries); Free edge (part of nail body that extends past the distal end of digit, avascular); Nail root (buried in fold of skin); Lunula (whitish crescent-shaped area at the proximal end of the nail body, vascular does not show through due to thickened area of epithelium; Hyponychium or Nail Bed (secures nail to fingertip); Epinychium or cuticle (narrow band of epidermis that extends from and adheres the lateral border of the nail wall, occupies proximal border of nail and consists of stratum corneum); Nail matrix (proximal portion of epithelium deep to nail root, superficial portion divide mitotically to produce more cells)

Synthesis of Vitamin D

Precursor of molecule in the skin by ultraviolet uv rays in sunlight. Enzymes in the liver and kidney then modify the activated molecule producing calcitriol, the most active form of vitamin d. Calcitriol is a hormone that aids in the absorption of calcium from foods in the GI tract into the blood. About 10-15 minutes at least twice a week is require for vitamin d synthesis. Vitamin D is activated in a response to an infection such as influenza. Believed to enhance phagocytic activity and increase the production of antimicrobial substances in phagocytes, regulate immune functions and help reduce inlammation.

Aging and Integumentary system

Reach late 40's when becomes noticeable, age related changes occur in proteins in the dermis. Collagen fibers decrease in number, stiffen, break apart and disorganize into a shapeless, matted tangle. Elastic fibers loose some of their elasticity, thicken into clumps and fray (accelerated in smokers), fibroblasts, produce collagen and elastic fibers decrease in number - producing crevices (wrinkles); langherhans cells decrease in number, macrophages become less-efficient phagocytes and decrease the immune responses. Sebaceous glands decrease in size leading to dry and broken skin more susceptible to infection; sweat production decreases relating increased heat stroke to aging; decreased number of functioning melanocytes, resulting in gray hair, and atypical skin pigmenting hairs; hair loss increases as hair follicles stop producing hairs, 25% of men show hair loss by age 30 and 2/3 have significant hair loss by age 60, males and females develop pattern baldness; age spots from increased size of melanocytes; walls of blood vessels in dermis become thicker and less permeable, subcutaneous adipose tissue is lost; aged skin is thinner, migration of cells from epidermal to basal layer slows; skin heals poorly and susceptible to skin conditions such as cancer and pressure sores; rosacea is a skin condition that affects mostly light-skinned adults between ages 30 and 60. and causes redness, tiny pimples and noticeable blood vessels, usually in central area of face. Growth of nails and hair slow, become brittle due to dehydration or repeated use of cuticle remover or nail polish

Apocrine sweat glands

Simple, coiled tubular glands; mainly in skin of axilla, groin, areola of breasts, bearded regions of face in adult males; exocytosis secretions; secretory portion in upper subcutaneous and lower dermis and open the excretory duct to hair follicles; milky and yellowish in color; contains lipids, proteins, lactic acid, ions (Na+ and Cl-), glucose, urea, uric acid, ammonia, amino acids, glucose; odorless other than when mixed with bacteria on surface of skin - then it is musky; start to function at puberty; active during emotional sweating, sexual activities, not active during thermoregulation

Eccrine Sweat Glands

Simple, cuboidal tubular glands more common than apocrine sweat glands; throughout skin in most regions of the body especially in skin of forehead, palms and soles, margins of lips, nail beds of fingers and toes, glans penis, glans clitoris, labia minora, eardrums; secretory portion located deep in the dermis (sometimes in upper subcutaneous layer), excretory duct pushes through the dermis and epidermis and ends as a pore at the surface of the epidermis; sweat consists of water, ions (Na+ and Cl-), urea, uric acid, ammonia, amino acids, glucose, and lactic acid; regulates body temperature through evaporation called thermoregulation; thermoregulatory sweating is the action of the body using thermoregulation to regulate body temperature, forms on scalp, forehead, then to rest of body, last on soles and palms; insensible perspiration is sweat evaporizing on skin surface before it is perceived as moisture); moisture on skin from sweat is called sensible perspiration; emotional sweating occurs on palms, soles and axillae and then spreads to rest of body; Eccrine glands eliminate wastes such as urea, uric acid, ammonia; start functioning after birth

Contribution of the Integumentary System for all the body systems

Skin and hair provide barriers that protect all internal organs from damaging environments externally; sweat glands and skin blood vessels regulate body temperature; needed for proper functioning of other body systems

Contribution of the Integumentary system on the Digestive system

Skin helps activate Vitamin D to hormone calcitriol which aids in absorption of calcium and phosphorous in the small intestine

Contribution of integumentary system for the skeletal system

Skin helps synthesize vitamin D needed for maintaining healthy bones by absorbing calcium and phosphorous from the diet

Contribution of Integumentary system for the Lymphatic System and Immunity

Skin is first line of defense in immunity providing barriers and chemical secretions that protect the body from invading microbes; langerhans cells in epidermis recognize and process foreign antigens; macrophages in dermis phagocytize microbes that penetrate through the epidermis

Contribution of the Integumentary system for the muscular system

Skin provides calcium ions needed for muscle contraction

Thick skin

Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and thick stratum corneum

Thin skin

Stratum basale, stratum spinosum, stratum granulosum, thin stratum corneum

Dermatoglyphics

Study of the pattern of epidermal ridges

Skin Glands

Sudoriferous (sweat), Sebaceous (oil), ceruminous glands (wax). Mammary glands are specialized sudoriferous glands that secrete milk

Stratum spinosum

Superficial to stratum basale; numerous keratinocytes arranged in 8-10 layers; superficial layers more flattened; keratinocytes produced by stem cells in the basal layer, have same organelles as the basal layer and are able to divide; coarser bundles of keratin in intermediate filaments; a spine like projection has bundles of keratin intermediate filaments that attach to desmosomes that tightly join the cells together (provides strength, flexibility to skin; Langerhans cells and projections of melanocytes

Melanocytes

Synthesize melanin from the amino acid tyrosine in the presence of an enzyme called tyrosinase; synthesis occurs in an organelle called melanosome, increasing the melanin production; UV exposure increases the darkness and amount of melanin.

Functions of Skin

Thermoregulation; blood reservoir; protection; cutaneous sensations; excretion and absorption; synthesis of vitamin d

Products available to diminish aging or sun-damaged skin

Topical products: bleach skin to tone down blotches and blemishes (hydroquinone) or decrease fine wrinkles and roughness (retinoic acid) Microdermabrasion: use of tiny crystals that under pressure remove and vacuum the skins surface to improve texture and reduce blemishes Chemical peel: application of a mild acid to removed surface cells to improve the skin texture and reduce blemishes Laser resurfacing: use of laser to clear up blood vessels near the skin surface, even out blotches and blemishes and decrease fine wrinkles Dermal fillers: injections of collagen from cows, hyaluronic acid, calcium hydroxylapatite, or polylactic acid that plumps up the skin and reduces wrinkles, fill furrows and lines around nose, mouth and eyebrows Fat transplantation: fat from one part of the body is moved to another location such as the eyes Botulinum toxin: diluted version of a toxin that is injected into the skin to paralyze the muscles that cause the skin to wrinkle Radio frequency nonsurgical facelift: radio frequency emissions to tighten deeper layers of skin of jowls, neck and sagging eyebrows and eyelids Facelift, browlift and necklift: invasive surgery to remove loose skin and fat and underlying connective tissue and muscle are tightened

Contribution of Integumentary system for the nervous system

Touch, thermal, pressure and pain sensations from the nerve endings in the skin and subcutaneous layers send impulses to the brain

Keratin

Tough fibrous protein that protects the body from heat, abrasion, microbes, chemicals; produce lamellar granules (release a water repellant sealant that decreases the water intake and loss and prevents foreign particles from entering the skin)

Nail Growth

Transformation of superficial cells of the nail matrix into new cells; growth rate determined by rate of mitosis in matrix cells, influenced by factors such as age, health and nutrition. Nail growth varies due to the season, time of day, environmental temperature. Average growth is 1mm (0.04 inches) per week, somewhat slower in toenails, longer the digit faster the nail growth.

Contribution of Integumentary system for the Cardiovascular system

Widening and narrowing of skin blood vessels from local chemical changes in the dermis help adjust blood flow to the skin

Carotene

Yellow-orange pigment that gives egg yolks and carrots their color. Precursor of Vitamin A, synthesized for pigments for vision, stored in stratum corneum and fatty areas in the dermis and subcutaneous layer in response to dietary intake and can cause orange skin if consume too much

Melanin

Yellow-red or brown-black pigment that contributes to skin color and protects skin from damaging UV light, and inside the keratinocytes protects the side of the nucleus that is facing the skin to prevent damage to the nucleus and DNA from harmful UV rays. Melanin granules protect keratonocytes, melanocytes themselves can damage from UV light