integumentary system

what does the integumentary system consist of

skin, nails, hair, sweat glands, sebaceous glands

what are the 2 layers of the skin

dermis and epidermis

what are the cells of the epidermis

keratinocytes, melanocytes, dendritic cells, merkel cells

what are keratinocytes

cells that produce keratin

what is keratin

fibrous protein that gives the skin its protective properties

what are melanocytes

cells deep in the epidermis that produce melanin

where do melanosomes transfer to and what do they protect from

they transfer to keratinocytes and they protect from UV damage

what are dendritic cells

immune cells that are deep in the epidermis

what are merkel cells

sensory receptors that sense touch

what is the major cell in the epidermis

keratinocytes

what are the 5 layers of the epidermis

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

how thick is the stratum basale

single layer thick

what is the percentage of melanocytes in the stratum basale

10-25%

what does the stratum basale layer do

has 1 row of stem cells that actively divide yielding 2 new cells each time; 1 cell dies and one moves to the top

how thick is the stratum spinosum

several layers thick

what cells is the stratum spinosum abundant in

melanosomes and dendritic cells

what does the stratum spinosum have

prekeratin filaments attached to desmosomes that allow for tension and pulling resistance

how thick is the stratum granulosum

4-6 layers thick but the cells are flattened

what happens in stratum granulosum

cells flatten and keratinization begins

how thick is the stratum corneum

20-30 rows of flat anucleated keratinized dead cells

what does the stratum corneum do

protect deeper cells and abrasions/penetrations, prevents water loss, and is a barrier against biological, chemical, and physical assaults

what are the cells of the dermis

fibroblasts and macrophages

what does the dermis contain

nerves, blood vessels and lymphatic vessels

what are the layers of the dermis

papillary and reticular layer

what is the papillary layer

it is loose collages, elastic fibers and blood vessels

what does the papillary do

allows for phagocyte patrol for microorganisms

what is the reticular layer

coarse dense fibrous connective tissues

which layer is 80% of dermal thickness

reticular layer

what do elastic fiber do in the reticular layer

give stretch recoil properties

what do collagen fibers do in the reticular layer

gives strength

dermal papillae

dermis sends fingerlike projections into epidermis

what does dermal papillae do in thick skin

it gives epidermal ridge -- finger tips

cutaneous plexus

blood vessel between reticular layer and hypodermis

cleavage lines

many collagen fibers running parallel to skin surface

flexure lines

dermal folds near/at joints

what 3 pigments contribute to skin color

melanin, carotene and hemoglobin

what is melanin packed into

melanosomes

where is melanin sent

to shield keratinocyte DNA from UV damage

what are the 2 forms of melanin

reddish yellow to brownish black

what does melanin do

makes skin darker to protect it from UV damage

what is caarotene

a yellow to orange pigment

where does carotene accumulate in

stratum corneum and hypodermis

what does carotene do

converts vitamin a for vision and epidermal health

what does hemoglobin do to skin if there is less melanin present

makes it a fairish pink color

what are the 4 skin color alterations that can indicate disease

cyanosis, pallor, erythema, and jaundice

cyanosis

blue color due to low hemoglobin oxygenation

pallor

pale color due to anemia, LBP, fear

erythema

red color due to inflammation, fever, allergy

jaundice

yellow color due to liver disorders

what is hair

dead keratinized cells

what is the function of hair

warns of insects on skin, head hair guards against physical trauma, protects from heat loss and shields from sunlight

what are the regions of the hair

shaft and root

shaft

area that extends beyond from scalp; keratinization is complete

root

area within scalp; keratinization still happening

where is hair not located

palms, soles, lips, nipples, parts of external genitalia

what are the 3 parts of the hair shaft

medulla, cortex, cuticlem

medulla

central corec

cortex

several layers of flattened cells that surround medulla

cuticle

outer layer

what are hair pigments created by

melanin in hair follicles

where does the hair follicle extend from

dermis to epidermal surface

hair bulb

expanded area at deep end of follice

hair follicle receptor

sensory nerve endings wrapped around bulb

what is the follicle wall composed of

peripheral connective tissue sheath, glassy membrane, epithelial root sheath

peripheral connective tissue sheath is derived from

dermis

glassy membrane

thickened basal lamina

epithelial root sheath derived from

epidermis

hair matrix

actively dividing bulb area that produces hair cells

arrector pili

small band of smooth muscle that attached to follice

what is the arrector pili also known as

goosebumpsh

air papilla

dermal tissue capillaries that supplies nutrients to growing hair

what is vellus hair

pale fine body hair

what is terminal hair

coarse long hair

where can vellus hair be found

on children and adult female

where can terminal hair be found

scalp, eyebrow, axillary and pubic regions

difference between alopecia and true baldness

alopecia is hair thinning after 40, while baldness is genetically determined and sex influencedm

male pattern baldness

follicle response to DHT

nails are

modifications of epidermis that contains hard keratin

what do nails consist of

free edge, nail plate, root

what is the thickened portion of bed that is responsible for nail growth

nail matrix

nail fold

skin fold that overlaps nail border

eponychium

fold that projects onto nail body surfacew

hat is eponychium also known as

cuticle

hyponychium

area under plate free edge that accumulated dirtw

hat causes a nails pink color

underlying capillaries

where are sweat glands located

everywhere except nipples and parts of genitalia

what is sweat glands also know as

sudoriferous

what are the 2 main types of sweat glands

eccrine and apocrine

how do sweat glands do to ducts

by myoepithelial cells contracting and forcing them into ducts

what is the most numerous type of gland

eccrine

where are eccrine glands found

palms, soles, foreheadw

what do eccrine secrete

sweat

what is the function of eccrine glands

thermoregulation

where are apocrine glands found

axillary and anogenital areasw

hat do apocrine glands secrete

viscous milky/yellowish sweat that contains fatty substances and protein

what are modified apocrine glands

ceruminous and mammary

ceruminous glands

line external ear canal and secrete cerumen

mammary glands

secrete milk

where are sebaceous glands found

everywhere except thick skin of palms and soles

sebaceous glands are inactive until

puberty