epithelium Flashcards
functions of epithelium
absorption, secretion and provide barrier
what function of epithelium do all types of epithelium posses?
provide barrier
specialized functions of epithelium
transport molecule across epi, prevent transport of material, sensory
what are the 2 parts of a basement membrane
basal lamina and reticular lamina
origin of basal lamina
produced by epithelial cells
origin of reticular lamina
produced by fibroblast in connective tissue
partial basement membrane
basal lamina only
function of basement membrane
provide attachment surface for epi. cells, limit stretch (protection), molecular filter
epithelium: vascular or avascular
avascular
what other type of tissue is epi associated with?
vascular connective tissue
why is epi associated with connective tissue?
CT provided nutrition and oxygen; provides defense
types of cell junctions in epithelium
zonula occludens,, zonula adherens, macula adherens and gap junctions
zonula occludens, type of cell junction in epi.
aka tight junctions; share intrinsic membrane proteins between cells
function of zonula occludens
strong attachment and prevent passage of material between cells
zonula adherens type of cell junction in epi.
aka adhesion belt; linkage proteins and marginal bands
linkage proteins
weak attachment between 2 cells in the zonula adherens
marginal bands
part of the cytoskeleton that attach to cell membrane in the zonula adherens
functions of zonula adherens
weak attachment and structural stability
macula adherens type of cell junction in epi.
aka desmosome; strong attachment
gap junctions type of cell junction in epi.
aka connexon
function of gap junction
strong attachment and transport materials
how does macula adherens (desmosome) work
protein plaque within adjacent cells link together via transmembrane proteins
how does gap junctions (connexon) work
cylinders of proteins (connexins) with in adjacent cells like
hemidesmosome
half of macula adherens
location of simple squamous
lung, parietal layer of bowman’s capsule (kidney), serosa on the outside of organs
function of simple squamous
barrier and living filter
location of simple cuboidal
exocrin ducts, thyroid follicular cells, kidney tubules
function of simple cuboidal
barrier, secretion, absorption
location of simple columnar
stomach, small intestine, gall bladder and LARGE exocrin duct
function of simple columnar
barrier, secretion and absorption
location of ciliated pseudostratified
trachea, repiratior region of nasal cavity, bronchi
other name for ciliated pseudostratified
respiratory epithelium
other name for respiratory epithelium
ciliated pseudostratified
types of cells in ciliated pseudostratified
ciliated columnar, goblet cells and basal cells
how is cilia anchored to ciliated columnar
by basal bodies to the apex of the cell
function of the ciliated columnar
to move mucus
function of goblet cells
produce mucus
basal cells
short pyramidal cells that do not reach surface in respiratory epi
function of basal cells
stem cells that divide through mitosis
basal cells divide into:
basal cells OR goblet cells OR ciliated columnar
microvilli
aka brush border of striated border
function of microvilli
increase surface area and increase absorption
location of microwilli
kidney tubule cells and small intestine
stereocilia
extremely long microvilli
function of sterocilia
increase surface area
location of sterocillia
epididymis and cochlear hair cells
function of cilia
to move something over surface
cells with cillia…
have many mitochondria and no absorption or secretion due to basal bodies blocking surface
location of cilia
trachea and fallopian tube
glycocalyx
surface layer of glycoproteins and carbohydrates that cover some epi
glycocalyx is produced by…
epithelial cells
function of glygocalyx
protection and cell recognition
location of glycocalyx
stomach and small intestine
location of stratified squamous
esophagus, oral cavity, tongue and vagina
function of stratified squamous
protection from abration
problems with stratified squamous
no protection from drying, limited thickness (increased thickness will decrease nutrient diffusion and cause cell death)
location of keratinized stratified squamous
skin
function of keratinized stratified squamous
protection in a dry enviroment
layers of keratinized stratified squamous
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum and stratum corneum
stratum basale
1-2 layers of keratinocytes; mitotic and close to dermis
stratum spinosum
multiple layers of “star” cells; produce lipids and keratohyalin vacuoles; thickness can vary
strantum granulosum
upper most 1-2 layers of LIVING keratinocytes; flattened, condensed keratinohyalin vacules
stratum lucidum
thin layer of DEAD or DYING keratinocytes; present on ly in thick skin
stratum corneum
layer of dead cells, karatin and lipids; variable thickness
function of stratum corneum
protection from water loss, abrasion and microorganisms
epidermal pegs
aka rete ridges; contribute strength to epi by increasing surface area for attachment to CT below
dermal papillae
contribute strength to epi by increasing surface area for attachment to CT belos
skin color is influenced by:
number of melanosomes, size of melanosomes and placemnt of pigment/melanosomes within a cell
protection from UV increases or decreases with age?
decreases; melanosomes decrease in number and skin lightens
langerhans cells
aka antigen presenting cells; recognize external foreign antigens
location of langerhans cells
stratum spinosum; and stratified squamous epi in esophagus and vagina
merkel cells
provide touch receptors; associated with nerve endings and respond to pressure
location of merkel cells
stratum basale
clinical connection between langerhans cells and melanocytes
melanocytes increase when exposed to UV light while langerhans cells decrease when exposed to UV light
location for stratified cuboidal
larger ducts in sweat glands and salivary glands
function of stratifed cuboidal
increase protection and structure
stratified cuboidal
2 layers: basal layer is flatted and superficial layer is cuboidal
location of stratified columnar
large ducts in pancreas, parts of the male urethra, conjuctiva of eye
stratified columnar
2 layers; basal layer is flattened to cuboidal shape and superficial layer is columnar
location of transitional epi
most of the urinary tract
transitional epi
aka urothelium; multiple layers thick
function of transitional epi
protection (provides a barrier for urine) and STRETCH
specializations for transitional epi
thin, fenestrated basement membrane; large, round superficial cells; well developed zonula occludens
what is unusual about transitional epi cells
many are bi-nuclear
why do transitional epi cells get more oxygen
due to fenestrated basement membrane and shorter diffusion distance when epi is stretched
subcatagories of epi glands
exocrine and endocrine
exocrine secretion
product is relased into a duct of directly onto epi surface
parenchma
function component; ex. muscle cell
stroma
structural component; blood vessles, nerves, CT, tendons
classification of exocrine glands
morphology, method of secretion or product secreted
morphology classification of exocrine glands
secretory units: tubular vs acinar; duct arrangement: branched vs unbranched
method of secretion classification of exocrin glands
merocrin (eccrine), holocrin or apocrin
merocrin secretion
method of exocrine secretion that uses exocytosis, does not cause cell damage and relasese only secretory product (generally no odor)
holocrine secretion
method of exocrin secretion where mature cells die and release product, vacuole content, lipids, cell membrane, organelles and etc; associated with odor and bacteria
apocrin secretion
method of exocrin secretion where vacuoles pinch off from cell; minimal cell damage; secretory products of intack vacules, cytoplasmn and cell membrane; associate with odor and bacteria
examples of merocrin glands
goblet cell, salivary glands, pancreas and all sweat glands in children
examples of holocrine glands
sebaceous glands, tarsal (meibomian) glands of eyelid
examples of apocrine glands
lactating mammary glands, adult sweat glands (pubic/axillary), ceruminous glands in external auditory canal, ciliary (moll’s) glands in eyelid
acinus
smallest division of a gland; a croup of cells surrounding a cavity
serous demilune
small group of serous cells attached to a mucus acinus
myoepithelial cells
cells with epithelial origin that are contractile; wrap around the acini and sometimes the ducts in some exocrine glands
myoepithelial cells are found in:
salivary & sweat glands, lacrimal glands, lactating mammary glands
funcion of myoepithelial cells
assist secretion
serous glands produce:
proteins (enzymes)
example of serous glands
pancreas parotid gland, chief cells in stomach
characteristics of serous glands
cells are trapezoid in shape, nucleus is typically round and noticeable, cells pick up stain
examples of mucus glands
goblet cells, mucus cells in stomach, minor salivary glands in tongue and palate
characteristics of mucus glands
cells stain light, nucleus is usually flat & peripheral, cells are trapezoid in shape
mixed glands produce:
mucus & serous (protein/enzmes) products
characteristics of mixed glands
serous demilunes are posible
exocrine regulation
myoepithelial cells: influence contraction and secretion of product; hormonal; blood supply: increased oxygen increased activity/secretion
endocrine secretion
paracrine secretion and autocrine secretion
paracrin secretion
type of endocrine secretion where signaling cell is close to target cell; hormone does not enter blood
autocrine secretion
type of endocrine secretion where signaling cell is own target
regulation of endocrine secretion
hormonal & ANS