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Ms. Eddy's BIO210 sec 008

Organs of the integument system

skin, hair, nails, and skin glands (sweat & sebaceous)

primary function, integument

protection

Primary layers of the integument

2 layers: epidermis and dermis

epidermis

outer, thinner layer of skin

epidermis tissue type

membranous epithelium (stratified squamous epithelium-keratinized)

keratinocytes

protection and waterproofing, most numerous and import cells in the epidermis, filled with (or in the process of becomine filled with) keratin

keratin

strong protein; protects and waterproofs the skin

keratinization

process by which cells in the epidermis become filled with keratin and moved to the skin's surface (cells die in the process) causes both the cell's nucleus and organelles to disintegrate which causes the cell to die

melanocytes

produce and store melanin; have long branching processes and are scatterd among the keratinoctes of the stratum basale; transfer pigment granules called melanosomes into the keratinocytes

functions of melanin

responsible for color of skin, hair, and eyes; filters uv ligh

langerhan's cells

can travel, track down bacterai, provide defense against foreigh invaders (work with immue system) similar to leukocytes)

3 cell types of the epidermis cells

keratinocytes, melanocytes, and langerhan's cells

cell layers of the epidermis

5 layers: stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale

stratum corneum

"hardened layer": cells in this layer are totally filled with keratin (replaces cytoplasm) known as the barrier area, cells at the surface of this layer are dead; what you see when you look at the skin; consists of 20 to 30 layers of deady, scaly interlocking keratinized cells

stratum lucidum

"clear layer" cells in this layer have a clear appearance (keratin precursor/immature form) only present in thick skin within the palms of the hands and the soles of the feet; cells that occupy this layer appear pale and featureless and have indistinct boundaries teh keratinocytes are flattened adn filled with the translucent protein called eleidin

stratum granulosum

"granular layer": cells in this layer are filled with granules (keratin precursor) keratinization begins in this layer

stratum spinosum

"spiny layers": cells in this layer have an irregular shape (plasma membrane modified to hold tighlty together); rich in RNA (preparation for keratinization) each time a keratinocyte stem cell in the stratum basale divides a daugher cell is pushed toward the external surface from the stratum basale

stratum basale

"base layer": the innermost layer of epidermis; mitosis occurs in this layer; is a single layer of cubodial to low columnar cells tightly attached to an underlying basemetn memembrane; have three type of cells: kerationocytes, melanocytes, and tactile cells

turnover (regeneration) time

time required for epithelial cells to form in the stratum basale and migrate to th skin's surface; takes about 35 days on average (maintains a constant skin thickness) application: shortened turnover time results in formation of callus

epidermal proliferating unit (epu)

each group of 8-10 basal cells along with the vertical colums of cells above (up to the skins's surface) epidermis grows in units- not as whole

dermal

epidermal junction; the union between the eidermis and the dermis; a basement membrane

functions of the epidermal junction

tightly "glues" the epidermis to the dermis; provides support for the epidermis; serves as a partial barrier between the epidermis and the dermis

dermis

inner, thicker layer of skin; tissue type: connective tissue called the "true skin" (thicker and gives strength to skin)

structures present in the dermis

sensory receptors, muscle fibers, hair follicles, sweat & sebacous glands, blood vessels

sensory receptors

specialized nerve endgins for hot, cold, pressure, pain, and touch (skin functions as a sene organ)

muscle fibers

two types skeletal and smooth

skeletal muscle fiber

located only in the dermis of the face ans scalp, function: voluntary movement of the face and scalp

smooth muscle fiber

arrector pili muscles, attached to hair follicule, the most abundant of the 2 types of muscle fibers; produces "goose bumps"

hair follicles

tubes that hold hairs

sweat, sebaceous glands

produce oil, skin glands

blood vessels

the derms contains an extensive network of blood vessels that play an important role in regulation of body temperature

layers of the dermis

papillary layer and reticular layer

papillary layer

(dermal papillae/fingerprings) thin superficial layer of the dermis; folded--> folds know as dermal papillae forms fingerprints (thick skin); composed of areolar connective tissue and derives its name from the projections of the dermis called dermal papillae; contains the capillaries that supply nutrients to the cells of the epidermis

reticular layer

the deeper, major portion of the dermis that extends from the papillary layer to the underlying subutaneous layer(langer's lines/cleavage lines) inner, thicker layers of dermis; contains many protein fibers; contains many protein fibers (collagenous and elastic) made up of moslty dense irregular connective tissue

collagenous fibers

most of the fibers are this type form langer's/clevage lines (pattern unique to each individual) surgical incisions should be made parallel to langer's lines for better wound healing

elastic fibers

if overstretched and torn, forms stretch marks

subcuatneous layer

(hypodermis; superficial fascia) tissue type: connective tissue (loose areolar and adipose)

skin color primary determinant

amount of melanin produced; primary determinant of skin color is the amount of melanin produces by melanocytes (not hte number of melanocytes)

how melanocytes produce melanin

they convert an amino acit (tyrosine) into melanin (the proces is regulated by an enzyem) they then transfer the melanin to other cells in the epidermis

factors that afffect melanin production

heredity, sunlight, hormones, & age

heredity (DNA)

the most important fator that determine the amount of melanin produced by melanocytes; 4-6 pairs of genes control howmuch melanin melanocytes will produce; however these are several factors that can modifiy the effect of heredity

sunlight

prolonged exposure to sunlight causes melanoctes to increase their production of melanin and skin to darken (a rotective mechanism- melanin protects skin cells from uv light)

hormones

the secretion of certain hormones from the anterior pitutary gland (MSH, ACTH) increases the production of melanin; normally the secretion of these is carefully regulated by genes and negative feedback mechanisms; however, under certain abnormal conditions (diseases) the secretion of these hormones may increase, causing skin to darken

age

increasing age may cause melanocytes to decrese their production of melanin (the converting enzyme becomes less active); responsible for graying hair, blotchy coloring of skin

skin color changes unrelated to melanin production

these changes in skin color tend to be temporary and are best seen in fair-skinned indiviuals: amount of blood flow to skin and amount of oxygen in blood

amount of blood flow to the skin

if some condition causes skin blood vessels to dilate or contract changing the color of the skin ex: excersie

amount of oxygen in the blood

if red blood cells are carryign less oxygen thatn normal (i.e. may ocur in certain respiratory or cardiovascualr diseases) skin may appear bluish in color

melanin

skin pigment produced in response to ultraviolet light exposure

tactile cells

aslo called merkel cells are few in number and foudn scattered among the cells within the stratum baslae, are senstive to touch and when compressed they relesae chemicals that stimualte sensory nerve endings providing information about objects touching the skin

eleidin

an intermediate product in the process of keratin maturation

anucleate

lacking a nucleus

thick skin

found on the palms of the hands, the soles of the feet, and coresponding surfaces of fingers and toes, all five epidermal strata occur here ranges from between 0.4mm to 0.6 mm thick, houses sweat glands but has no hair follicules of sebacous glands

thin skin

covers most of the body, lacks a stratum lucidum only has four layers; conatins hair follicules; sebaceous glands, and sweat glands ranges from 0.075 mm to 0.150mm thick

skin color

normal color results from a combination of the colors of hemoglobin, melanin, and carotene

hemoglobin

an oxygen-binding protein present in red blood cells. exhibits a bright red color upon binding oxygen thus giving blood vessles in teh derms a reddish tint that is seen most easily in lightly pigmented individuals

melanocyte activity

it is not the number of the melanocytes but activity level and the color of the melanin produced by the melanocytes varies among individuals

carotene

a yellow-oragne pigment that is aquired from varoius yellow-orange vegetables, such as carrots, corn and squashes accumulates inside the keratinocytes of the stratum corneum and in the subcutatneous fat, converted into vitamin A

nevus

commonly called a mole is a harmless localized overgrowth of melanin-forming cells on rare occasions can become malignant

freckles

yellowish or brown spots that represent localized areas of increased melanocyte activity

hemangioma

is an anomaly that results in skin discoloration due to blood vessesl that proliferate to form a benign tumor

capillary hemangiomas

strawberry-colored birth-marks, apear in teh skin as bright red to deep purple noduels that are usually present a birth and disapper in childhood

cavernous hemangiomas

also know as port-wine stains, involve larger dremal blood vessels and may last a lifetime

friction ridges

the contours of the skin surface follow ridge patterns varrying from small conical pegs (in the skin) to complex arches, formed from large folds and valleys of both dermis and epidermis, help increase friction on contact four types: arch, whorl, loop, and combination

lines of clevage

(tension lines) identify the predominant orientation of collagen fiber bundles are surgically significant because any procedure resulting in a cut at right angles to these is pulled open as a result of the recoil resulting from cut elastic fibers, resulting in slow healing and slower healing times

collagen fibers

contribute to the observed physical characteristics of the skin, impart tensile strength

elastic fibers

contribute to the observed physical characteristics of the skin, allow some stretch and recoil in teh dermis during normal movement activities

striae

result as the skin stretches and collagen fibers break, also know as stretch marks

innervation

dermis has an extensive network or ___ which is the distribution of nerve fibers

vasoconstriction

the diameter of the vessles narrows so relatively less blood can travel through them, occurs when the body is trying to conserve heat and is the reason we look paler when exposed to cold temperatures

vasodilation

the diameter of teh vessels increases, so relatively more blood can travel through them. occurs to allow more blood to travel to the body surface and excess heat may be lost if the body is too warm. this is why we become flush when excerting ourselves

subcutaneous layer

deep to the integument, also called the hypodermis or superficial fascia: not part of the integument and consists ofboth areolar connective tissue and adipose connective tissue, helps to bind the dermis to the underlying structures, pads and protects the body, acts as an energy reservoir, and provides thermal insulation, thicker in women

subcutaneous fat

when adipose connective tissue dominates in a subcutaneous layer

why are drugs injected into the subcutaneous layer?

because of the extensive vascular network that promotes rapid absorption

epidermal derivatives

appendages of the integument: nails, hair, and exocrine glands, formed during embryologic development as portions of the epidermis invaginated into the dermis

nails

scalelike modifications of the stratum coreneum layerprotect teh distal tips of the digits and prevent damage or extensive ditorition during jumping, kicking, or catching

free edge

the nails distal whitish part

nail body

pinkish part of the nail

nail root

proximal distal part embedded in the skin

nail plate

the nail body, root, and free edge form this part

nail bed

covered by the nail body, covers a layer of epidermis that contains only teh deeper, living cell layers of teh epidermis

nail matrix

thickened part of the nail bed, the activley growing part of teh nail

lunula

whitish semilunar area of the proximal end of the nail boy, has a whitish apperance becaue a thickened stratum basale obscures teh underlying blood vessels

nail folds

overlap the nail along the lateral and proxmial borders, folds of skin

eponychium

cuticle, narrow band of epidermis extending from the margin of the nail wall onto the nail body

hyponychium

is a region of thickened stratum corenum over which the free nail projects

brittle nails

are proen to vertical splillting and separation of the nail plate layers at the free edge. overexposure to water or to certain household chemicals can cause this

ingrown nail

occurs when teh edge of a nail digs into the skin around it, painful condition is first characterized by pain and inflammation at the site, if left untreated can cause infections. caused by overly tight shoes or improper trimming of nails

onychomycosis

a fungal infection that occurs in nails constantly exposed to warmth and mositure, fungus starts to grow under the nail and eventually causes a yellowish discoloration, a thickened nail, and brittle cracked edges. can result in permanent damage to the nail and a potential spread of infection. treatment is taking oral antifungal medications for 6-12 weeks

yellow nail syndrome

occus when growth and thickening of the nail slows or stops completly as the nail growth slows the nails become yellwoish or soemtiems greenish, can sometimes be an outward sign of respiratory disease

spoon nails

koilonychia, a nila malformation where the outer surface of the anils are concave instead of convex. are frequently a sign of iron deficiancy

beau's lines

run horizontally across the nail and indicate a temporary interference with nail growth at the time this portion of nail was formed. injury or illness can cause this can also be a sign of chronic malnutrition

hair

foudn almso everywehre on teh body except palms of the hands and palmar surface of the finders, the sides of teh soles fo the feet and toes, the lips, and portions of the external genitalia

pilus

a single hair, has the shape of a slender filament it is composed of keratinized cells growing from hair follicles that extend deep intot het dermis, often projecting into the underlying subcutanoues layers

lanugo

a fine, unpigmented, downy hair that first appears on the fetus in the last trimester of development.

vellus

the primary human hair adn si foudn on hte upper and lower limbs, is fine and unpigmented to lightly pigmented and replaces lanugo

terminal hair

usually coarser, pigmented, and longer than vellus, grows on the scalp and it is also the hair of teh eyebrows and eyelashes, during puberty replaces vellus hair in the armpits, pubic regions and in men the hair of the beard

what are the three parts of a hair

hair bulb, root and shaft

hair bulb

consists of epithelial cells adn is a swelling at the base where the hair originates in the dermis

hair bulb

surrounded by epithelium at the base of the hair bulb, composed of a small amount of connective tissue containing tiny blood vessels and nerves, living epithelial cells

root

the portion of the hair deep to the skin surface, consist of dead epithelial cell

shaft

portion of the hair that extends beyond the skin surface, consist of dead epithelial cells

hair matrix

a specialized type of keratinization occurs here, part of hair production. it is a structure at teh base of the hair bulb. epithelial cells near its center divide producing new cells that are gradually pushed toward the surface

medulla

not found in all hair types is a remant of the soft core of the matrix is composed of loosely arranged cells and air spaces, and contains flexible soft keratin.

cortex

serveral layers of flattend cells closer to the outer surface of the developing hair form the this relatively hard_____

cuticle

single cell layer around the cortex, coats the hair

hair follicle

an oblique tube that surrounds the hair root, extends into teh dermis and sometimes into the subcutaneous layer

connective tissue root sheath

the outer layer of the follicle wall, originates from the dermis

epithelial tissue root sheath

the innner layer of the follicle wall, originates from the epidermis

arrector pili

thin ribbons of smooth muscle, stimulation of this is usually a result of an emotional state, such as fear or rage, or a sa response to exposure to cold temperatures, produces goose bumps

Functions of hair

protection, heat retention, sensory reception, visual identification, and chemical signal dispersal

protection function of hair

the hair on the head protects the scalp from sunburnand injury, within the nostrils it traps particles before they enter the respiratory tract, protect against particles and insects entering the ear canal, eyelashes protect the eyes and eyebrows prevent sweat on the forehead from entering the eye

heat retention function of hair

hair on the head prevents the loss of conducted heat from the scalp to the surrounding air.

sensory reception function of hair

hair has associated tactile receptors (hair root plexuses) that detect light touch

visual identification function of hair

hair characteristics are important in determining age and sex, and identifying individuals

chemical signal dispersal

hairs help disperse pheromones, which ar echemical signals involved in attracting members of the opposite sex and in sex recognition

hair color

a result of the synthesis of melanin in the matrix adjacent to the hair papillae, variations in this are genetically determiend differences in the structure of melanin. environmental and hormonal factors can also effect this

hair growth

about one-third of a millimeter per day for 2 to 5 years, may attaina lenght of about a meter

hair dormant pahse

3 to 4 months after its growth phase

normal daily hair loss

10-100 strands daily, more than than can indicate a possible health problem or exposur to drugs, dietar factors, radiation, high fever or stress

alopecia

thinning of the hair, can occur in both sexes, usually as a resultof aging

diffuse hair loss

condition where hair is shed from all parts of the scalp, women primariy suffer from this condition which may be due to hormones, medications, or iron deficiency

male pattern baldness

loss of hair form only some regions of the scalp rather han uniformly, typically in men, caused by a combination of genetic and hormonal influences, relevant gene hs two alleles, expressed in the presence of high testosterone levels

skin's two type of glands

sweat (sudoriferous) glands, and sebaceous glands

sweat glands

two types, meocrine and apocrine: have a coiled, tubular, secretory portion that is located in the reticular layer of the dermis; contain myoepithelial cells

sweat gland duct

carries the secretion to the surface of the epidermis (in a meocrine gland) or into a hair follicle (in an apocrine gland)

sweat pore

the opening of the sweat gland duct on the epidermal surface, is an indented region

merocrine sweat glands

are the most numerous and widely dstruitubted seat glands, adult integument contains between 304 million; simple coiled tubular glands tht discharge tier secretions directly onto the surface of the skin; primary function thermoregulation

sweat

clear secretion released by merocrine sweat glands by exocytosis, consisits of approximately 99%water adn 1% other chemicals that include electrolytes

thermoregulation

regulation of body temperature by evaportaion of fluid form teh skin

apocrine sweat glands

are coiled, tubular glands that release thier secretion into hair follicles in the axillae, aroudn the nipples, in the pubic region, and in the anal region; the secretion they produce is viscous and cloudy and it contains both proteins and lipids that are acted upon by bacteria to produce a distinct, noticeable odor, begin workign around puberty

sebaceous glands

holocrien glands that produce sebum

sebum

an oily, waxy secretion, acts as a lubricant to keep the skin and hair from becoming dry, brittle, and cracked, has some bactericidal properties,simulated by puberty

ceruminous glands

modifited apocrein sweat glands located only in the external acoustic meatus (ear canal)

cerumen

secreted by ceruminous glands a waterproof earwax, help trap foreign particles or small insects and keeps them from reachign teh eardrum

mammary glands

modified apocrine sweat glands, both males and females have them but these glands oly become functional in pregnant and lactating femals when they produce milke

epidermis protection function

acts as a physical barrier that protects the entier body from physicla injury and trauma, protects against harmful chemicals, toxins, microbes, and excesive heat or cold, protects deeper layers from UV rays

prevention of water loss

the epidermis is water resistant and helps prevent unnecessary water loss, water cannot easily exit the skin, unless it is specifiically secreted by the sweat glands

Vitamin D3

also called cholecalciferol, is synthesized from a steroid precursor by the keratinocytes whn they are exposed to ultraviolet radioation, released ino the blood and transported to the liver where it is convereted to antoehr intermediate molecule adn then transported to the kidney where it is converetd to calcitriol

calcitriol

is the active form of vitamin D and is considered a hormone it increases the absorption of calcium and phosphate from the small intestine into the blood

acne

term used to describe plugged sebaceoisu ducts, typically becomes abundant beginnign at puberty because increase in hormone levels stimulate sebaceous gland secretion making the pores more prone to blockage

comedo

a sebaceous gland plugged with sebum

blackhead

open comedo because the plugged material has a dark blackish apperane

whitehead

closed comedo called this because the top surface is whitish in color

papule

dome shaped lesions are fluid-filled form red elevations on the skin and do not contain pus

pustule

dome shaped lesions which are filled with a mixture of white blood cells, dead skin cells, and bacteria called pus

nodule

similar to a pustule, but extending into the deeper skin layers and usually rupturing the hair follicle wall, prone to scarring

cyst

a large, fluid-filled nodule that can become severly inflamed and painful and can lead to scarring of the skin

secretion and absorption

skin exhibits a secretory function when it discharges substances from teh body during sweating, which occurs when the bod needs to cool itself off

selectively permeable

some materials are able to pass through it, while others are effectively blocked

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