L23 - integument Flashcards
what body parts does integument include?
skin, sweat glands, sebaceous glands, hair, nails
functions of skin
protect regulate temperature - sweat receive sensory input absorb UV light to make vitamin D excrete waste - sweat
dermis and epidermis tissue type
dermis is loose CT
epidermis is stratified squamous keratinized epithelium
thin skin vs. thick skin
THIN skin - found on most body surfaces
-can be hairy, oily, sweaty, etc.
- has hair follicles, arrector pilli m., sebaceous and sweat glands
- basale, spinosum, thin corneum
THICK skin - soles and palms, form fingerprints
- sweaty, subject to abrasion
- NO hair follicles/arrector pilli/sebaceous
- HAS sweat glands
- basale, spinosum, granulosum, lucidum, corneum
- prominent epidermal ridges, dermal papillae, true dermal ridges
epidermis function characteristics
- come from ectoderm
- stratified squamous keratinized epithelium
- epidermal ridges interdigitate with dermal papilla (aka rete ridges)
- avascular (nutrients come from dermis)
- sensory nerve endings
- cells are keratinocytes and non-keratinocytes
keratinocytes
- epithelial cells
- mitotically active (night) in stratum basale to renew skin
- cells migrate toward skin surface while accumulating keratin filaments
- desquamate 120-30 days
non-keratinocytes include…?
langerhans, merkel cells and melanocytes
Langerhans cell
function = defense
dendritic, antigen-presenting cells (present antigen to lymph node)
formed from bone marrow precursors that enter the bloodstream and epidermis and differentiate into Langerhans
mainly found in stratum spinosum and superficial dermis
pale cytoplasm, long cytoplasmic processes
have membrane-bound Birbeck (vermiform) granules which function in protection from antigens
Merkel cell
mechanoreceptors - fine, detailed tactile info (texture and shape)
in hair follicle base and fingertips, attached to keratinocytes by desmosomes
Merkel disk - dilated part of peripheral nerve process that senses and relays sensory info
Merkel cell neurite complex = Merkel cell + Merkel disc - unmyelinated, found in stratum basale
melanocytes
protect DNA - natural sunscreen
arise from neural crest cells
found in stratum basale and superficial dermis
cytoplasmic processes extend into stratum spinosum
make melanin for keratinocytes
make tyrosinase and send to melanosomes
same # melanocytes in all races, but pigmentation is determined by tyrosinase activity, # granules, size of granules, breakdown rate of melanin, and distribution
explain the process of tyrosinase production and conversion
tyrosinase is produced by rER in melanocytes
UV light activates tyrosinase
tyrosine is pumped into melanosomes by GA and is converted to melanin
melanin passes into cytoplasmic processes of melanocytes and is released via vesicles to nearby cells
vitiligo
autoantibodies attack melanocytes leading to unpigmented skin patches
albinism
tyrosinase defect/absence so no melanin is made
melanocytes are present
malignant melanoma risk factors and ABCDE diagnosis
risk factors: heredity, light skin, excess sunlight
A appearance (according to Patestas) - malignant cell nodules
B border
C color
D diameter - bigger than pencil eraser
E evolving
icthyosis
excessive keratin buildup (hyperkeratosis) leading to fishlike scales because no keratin is sloughed off
thick skin layers from innermost to outermost
basale (germinativum) spinosum granulosum lucidum corneum
thin skin layers from inner to outermost
basale
spinosum
thin corneum
*no lucidum or granulosum - deep layers have desmosomes
how does the basement membrane attach to epidermis to dermis
glues - carbs
anchors - collagen fibers
name 2 layers of dermis
papillary layer and reticular layer
stratum basale: function and description
innermost layer of thick skin, rests on BM
functions = cell renewal most intense mitotic activity occurs here
also anchors epidermis to basement membrane via hemidesmosomes and to neighboring cells via desmosomes
melanocytes found here
basal cell carcinoma
chronic sun exposure
subepidermal blood vessels present in a “pearly papule” on skin
stratum spinosum: function and description
function = binding, protection
thickest layer of thick skin epidermis
found between basale and granulosum
keratinocytes have intercellular “bridges” (interdigitating processes) connected by desmosomes, causing prickly appearance
contains tonofilaments (intermediate filaments - type of cytokeratin) in cell periphery and in “bridges”
contains Langerhans cells
note mitosis in basal layer
stratum granulosum: function and description
function = waterproofing
3-4 layers of diamond shaped cells with nuclei containing fragmented DNA
has many granules in the cytoplasm
describe 2 types of granules in stratum granulosum
keratohyalin granules - contain soft keratin (protein)
membrane-coating granules aka lamellar bodies - contain lipid which is excreted to ECS to waterproof
- this also stops nutrient passage to superficial cells (lucidum and corneum) die
stratum lucidum, function and description
function = protection subdivision of stratum corneum light staining no organelles, nonviable cells contains keratin filaments really only perceptible in thick skin
stratum corneum, function and description
thick layer of flattened, keratinized, dessicated, dead cells - no nuclei/organelles
friction results in thickening of this layer resulting in a callus
no desmosomes between superficial cells so easily desquamate near surface
deeper cells have desmosomes
dermis function and characteristics
- CT layer of skin
- arises from mesoderm
- function = strength (collagen), defense, nutrition/thermoregulation (capillary loops), sensation and stretch
- Meissner corpuscles (mechanoreceptors, fine touch) and Krause end bulbs
dermal papillae, dermal ridges and epidermal ridges
- dermal papillae are scallops in the dermis and epidermal ridges fill in between those mounds
- dermal ridges are parallel to and in between dermal papilla and these form fingerprints
describe the papillary layer of dermis
- superficial, thin layer of loose CT
- forms dermal papillae
- function = defense against invaders
- has collagen III (reticular) + elastic fibers + collagen VII (anchor)
- has fibroblasts, macrophages, plasma cells, mast cells
- has melanocytes
describe the reticular layer of dermis
- dense irregular collagenous CT (tensile strength) and thick elastic fibers (stretch)
- has collagen I fibers in bundles that are oriented in regular lines of tension (Langer’s lines)
- has fibroblasts, mast cells, lymphocytes, macrophages, fat cells
- has hair follicles, arrector pili muscles, sebaceous glands, and sweat glands
- has Pacinian corpuscles (pressure/vibrations) and Ruffini corpuscles (tensile forces)
- proteoglycans - dermatan sulfate
where can surgical incisions be made to minimize scarring?
oriented parallel to Langer’s lines
describe the functions and location of each: Pacinian corpuscle Ruffini corpuscle Meissner corpuscle Krause end bulb Langerhans cell Merkel cell
Pacinian corpuscle - pressure/vibe
Ruffini corpuscle - tensile forces
both in reticular layer of dermis
Meissner corpuscle - mechanoreception
Krause - unknown fxn
both in papillary layer of dermis
Langerhans cell - defense/antigen-presenting, in stratum spinosum
Merkel cell - mechanocreception, in stratum basale - fingertips for tactile
both in epidermis
which skin layers are injured in superficial (first degree), partial thickness (second degree) and full thickness (third degree) burns?
superficial burns = epidermis
partial thickness = papillary AND reticular layer of dermis
full thickness = hypodermis - not part of skin (bc its fascia) - and maybe underlying muscle (4th degree)
hypodermis characteristics
- NOT skin
- superficial fascia
- loose CT deep to dermis
- has adipose tissue
- varies in thickness
- injured in full thickness burns
name 3 types of glands in the skin?
eccrine sweat, apocrine sweat, and sebaceous
describe eccrine sweat glands
- function = thermoregulation
- simple coiled tubular glands
- also in dermis or hypodermis of entire body
- duct opens to epidermis
- has myoepithelial cells
- secretory segment = simple cuboidal to low columnar (or pseudostratified)
- duct segment = stratified cuboidal epithelium
innervation of eccrine and apocrine sweat glands?
postganglionic sympathetic fibers
- eccrine have cholinergic endings and piggy-back on arterial vessel walls
describe myoepithelial cells
- surround the secretory unit of both sweat glands and are covered by the basal lamina of eccrine sweat glands
- contain actin and myosin filaments for contraction which squeeze out the secretions
describe apocrine sweat glands
- found in axilla, areola and anal region (AAAA’s)
- modified apocrine glands include ceruminous glands of external auditory meatus and glands of Moll in eyelids
- larger than eccrine
- also found in deep dermis and hypodermis
- duct opens to hair follicle, superficial to sebaceous gland duct
- influenced by hormones @ puberty
- secretion is viscous and odorless when released onto skin until metabolized by bacteria
describe secretory and duct units of apocrine and eccrine sweat glands
- both secretory units are simple cuboidal to low columnar
- eccrine duct = stratified cuboidal
- apocrine lumen is larger than eccrine
- both use merocrine method
describe sebaceous glands
- dermis and hypodermis, throughout body, more # in scalp and face
- secrete sebum = cholesterol, triglycerides and dead cells
- are appendages of hair follicles
- influenced by hormones @ puberty
- acinus made of small basal cells (immature, periphery) and large round cells (mature, degenerating)
- duct made of strat squamous
- holocrine secretion
difference between sweat and sebaceous glands?
sweat = merocrine vs. sebaceous = holocrine sweat = columar vs. seb = strat squamous
describe 3 types of hair
vellus = short, soft, fine, pale, eyelids terminal = long, hard, coarse, dark, scalp and eyebrows lanugo = fetus
describe a hair follicle
hair bulb & shaft (3 layers)
hair bulb:
- hair root = matrix and dermal papilla
- internal root sheath = Henle’s layer (outer) + Huxley’s layer (middle) + cuticle (inner)
- external root sheath
hair shaft = medulla* (inner) + cortex (middle) + cuticle (outer)
*medulla present in thick hair
arrector pili muscles
smooth muscle attached to hair follicle @ midpt obliquely contraction raises hair "cradle" seb glands sympathetic innervation
nails - describe parts and functions
nail plate + nail bed + nail root/matrix
plate = hard keratin bed = strat. basale and spinosum matrix = nail growth - forms keratin for plate eponychium hyponychium lunula = white crescent
describe eponychium and hyponychium
- eponychium = nail cuticle, proximal fold, made of stratum corneum
- hyponychium = thickened epithelium under nail plate
