Exam 2 - Integument Flashcards
functions of integument (5)
- protection
- thermoregulation
- sensory organ
- metabolism (vit D synthesis, energy storage)
- excretion (excess water, salt, nitrogenous metabolic wastes through sweat)
where is thick skin found?
palms of hand and soles of feet
what is special about thick skin?
no hair follicles
where is thin skin found?
skin other than palms and soles
epidermis
keratinized stratified squamous epithelium that contains keratinocytes
what is the pattern of keratin accumulation in epidermal cells?
accumulate more keratin as they migrate from basal layer
maturation time for epidermal cell maturation/desquamation?
25-50 days
layers of epidermis
- stratum basale/germinativum
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum
stratum basale/germinativum
single layer of columnar to cuboidal cells that has many mitotic figures and contains intermediate filaments, desmosomes, and hemidesmosomes
what type of intermediate filaments are found in stratum basale?
10 nm tonofilaments
where are desmosomes found in stratum basale?
lateral and upper surface of cells
where are hemidesmosomes found in stratum basale?
bind cells to basal lamina
stratum spinosum
cuboidal, polygonal to slightly flattened cells with processes filled with intermediate filaments that terminate with desmosomes and has mitotic figures
what do stratum spinosum cells accumulate?
fibrillar protein cytokeratin that aggregates to form tonofibrils
stratum granulosum
3-5 layers of flattened polygonal cells with basophilic keratohyaline granules and oval/rod-like lamellar granules in cytoplasm
lamellar granules/keratinosomes
granules formed by lipid bilayers which that fuse with cell membrane and exocytose contents into intercellular spaces of stratum granulosum
function of lamellar granules?
penetration barrier to foreign materials and maintain hydration of body
product of lamellar granules?
glycolipid - acylglucoceramide
stratum lucidum
thin layer of eosinophilic, newly keratinized cells w/ no organelles or nuclei
where is stratum lucidum found?
only in thick skin, but not in all thick skin
what is eleidin?
transformation product of keratohyalin
where is eleidin found?
stratum lucidum cells
stratum corneum
15-20 layers of flattened, non-nucleated cells filled w/ keratin
squames
dead flattened cells
how does skin heal if epidermis injured?
surrounding basal cells migrate and divide to cover wound - retinol/vitamin A needed for keratinocyte differentiation
retinol
vitamin A
how far do first degree burns extend?
statum lucidum
how far do second degree burns extend?
stratum basale
how far do third degree burns extend?
dermis
where does keratinocyte differentiation occur?
from basal layer to spinosum or granulosum
what happens w/ keratinocytes in granulosum?
glycolipids secreted to form multilayered lipid layer on outside of cell membrane
what happens w/ keratinocytes in corneum?
protein complex of involucrin-small Pro-rich-loricrin and keratin-filagrin aggregates link to inside of cell membrane
melanocytes
pigment producing cells of stratum basale
what are melanocytes derived from?
neural crest cells
location of melanocytes
rest on basal lamina and send processes into spinosum
function of melanocytes
distribute melanin to other cells/hair by exocytosis (cytocrine secretion)
how do keratinocytes obtain pigment granules?
endocytosis
where does melanin formation occur?
within melanosomes - organelles derived from golgi
how is melanin produced?
oxidation of tyrosine to 3,4-DOPA by tyrosinase and transformation of DOPA into melanin
how does number of melanocytes differ b/w people of varying skin colors?
same number of melanocytes in everyone - difference is in melanin production
addison’s disease
lack of cortisol from adrenal cortex which causes overproduction of ACTH -> increases skin pigmentation
albinism
melanocytes do not make melanin
what causes vision problems in albinism?
abnormal retina development and abnormal nerve connections b/w eye and brain
vitiligo
loss of melanocytes - depigmentation; patchy areas on skin that lose pigment
what causes vitiligo?
unknown - possibly autoimmune or from sunburn
langerhans cells
star shaped cells mainly in spinosum but occasionally in dermis near blood vessels that contain Fc and complement C3 receptors
what are langerhans cells derived from?
bone marrow - macrophage lineage
function of langerhans cells
can migrate out of epidermis to lymph nodes and present antigens to T cells and/or differentiate into activated dendritic cells
what type of attachments do langerhans cells NOT form?
desmosomal attachments with other cells
what type of granules do langerhans cells contain?
Birbeck/vermiform granules
Birbeck/vermiform granules
membrane-bound, rod-like to racquet shaped granules that contain proteins (langerin) necessary for antigen uptake
merkel’s cells
tactile epithelium cells associated w/ sensory nerve endings that participate in 2-pt discrimination
location of merkel’s cells
primarily in thick skin of palms/soles
what does merkel cell cytoplasm contain?
small dense granules that are catecholamine-like neurosecretory granules
what is base of merkel cell in contact with?
peripheral neuron terminal
dermis composition
CT divided into papillary layer and reticular layer containing follicles, sweat glands, sebaceous glands, nerves, extensive capillary network
dermis function
supports epidermis and binds it to subQ (hypodermis)
dermal papillae
capillary network for thermoregulation and provides blood supply to epidermis by diffusion
dermal papillae counterpart in epidermis
epidermal ridges or rete ridges
what binds dermis to epidermis?
collagenous anchoring fibrils extending from basal lamina into anchoring plaques
papillary layer composition
loose CT w/ fibroblasts, mast cells, macrophages
reticular layer composition
dense irregular CT that is thicker than papillary layer
hypodermis
deeper continuation of dermis made of loose CT and adipose tissue
location of pacinian corpuscles
hypodermis near dermis-hypodermis jxn
pacinian corpuscles
pressure/vibration sensors (look like onions)
hair follicle
invagination of epidermis that terminates in hair bulb
dermal papilla
projects into hair bulb
what forms hair root?
epidermal cells covering hair bulb form hair root that produces and is continuous w/ hair shaft
hair medulla
cells at apex of dermal papilla that produce large, vacuolated, moderately keratinized cells
hair cortex
other cells around the papilla that differentiate into fusiform, heavily keratinized cells
hair cuticle
produced by cells more peripheral in the hair root
internal and external root sheath
produced by most peripheral root cells of hair
glassy membrane
thickened basal lamina that separates hair follicle from dermis
arrector pili muscles
smooth muscle bundles extending from dermis papillary layer to hair follicle CT sheath
hair follicle and wound healing
clonogenic keratinocyte stem cells migrate up the hair follicles to heal wound
sebaceous glands
holocrine glands that secrete oil
sebaceous gland distribution
100 glands/cm2 of skin, but face, forehead, scalp have 400-600 glands/cm2 - none on palms and soles
sebum
dead sebaceous gland cells + cell contents
holocrine gland secretion
as cells proliferate and differentiate, gland acini fills with cells containing fat droplets -> nuclei become pyknotic -> cells burst and release contents
acini
basal layer of undifferentiated flattened epithelial cells on basal lamina
sudiferous glands
eccrine (merocrine) sweat glands that open onto skin surface
what is the shape of sudiferous glands?
simple coiled tubuler gland
what nerve fibers do sudiferous glands receive?
cholinergic nerve fibers
where is secretory portion of sudiferous glands?
deep in dermis
cell types in sudiferous glands?
myoepithelial cells (contractile), dark cells, clear cells
secretion from sudiferous glands?
non-viscous secretion w/ little protein, but contains water, NaCl, urea, ammonia, uric acid (ultra filtrate of plasma)
dark cells of sweat glands
mucoid, pyramidal cells that secrete glycoproteins
clear cells of sweat glands
no secretory granules, but abundant glycogen - secrete water and electrolytes into intercellular canaliculi
apocrine sweat glands
sweat glands containing only one kind of secretory cell whose ducts open into hair follicles
apocrine sweat gland location
axillary, areolar, anal regions
apocrine sweat gland secretion
viscous, protein-containing secretion
what nerve fibers do apocrine sweat glands receive?
adrenergic nerve fibers
mechanism of secretion for apocrine sweat glands
merocrine mechanism of secretion
nails
plates of keratinized epithelial cells
where is nail root?
embedded in fold of skin
eponychium
cuticle - s. corneum of epithelium over nail root
nail plate
from nail matrix, lies on nail bed
nail bed
only s. basale and s. spinosum
nail matrix
extends from nail root to lunula
lunula
white crescent at base of nail
liver spots
big freckles on skin of older folks (lentigos) due to sun exposure - NOT related to liver
actinic keratosis
precancerous condition that presents w/ thick, scaly patches of skin
removal of actinic keratosis?
with liquid N
what cancer makes up 90% of skin cancers?
basal cell carcinoma - slow growing and treatable if found early
what cancer often develops from sun damaged areas?
squamous cell carcinoma - actinic keratosis due to sun damage
malignant melanoma
cancer derived from melanocytes that is hard to treat once metastasized
psoriasis
immune-mediated, genetic disease that presents w/ red, scaly patches of skin due to inflammation and hyperplasia -
what other clinical manifestations is psoriasis often seen with?
joint problems
