5.2 – Epithelial Tissue Flashcards
epithelial tissue (def)
consists of a sheet of closely adhering cells, one or more cells thick
upper surface usually exposed to the environment or to an internal space in the body
covers the body surface, lines body cavities, forms the external and internal linings of many organs, and constitutes most gland tissue
epithelial tissue (functions)
protection
secretion
excretion
absorption
filtration
sensation
between an epithelium and the underlying connective tissue is a layer called the ___
basement membrane
basement membrane contains…
collagen, glycoproteins, and other protein-carb complexes
blends into the proteins of the connective tissue
basement membrane serves to…
anchor an epithelium to the connective tissue
controls the exchange of materials b/n the epithelium and the underlying tissues
binds growth factors from below that regulate epithelial development
basement membrane (location)
b/n an epithelium and the underlying connective tissue layer
basal surface (def)
the surface of an epithelial cell that faces the basement membrane is its basal surface
apical surface (def)
the surface of an epithelial cell that faces away from basement membrane toward the body surface/internal cavity (lumen) or an organ
lateral surface (def)
surface of an epithelial cell that is b/n the basal and apical surfaces
what is the function of the basement membrane?
to adhere epithelial tissue to underlying connective tissue
which term is used to describe the free surface of an epithelium?
apical
which tissue type covers body surfaces, lines body cavities, forms the internal and external linings of many organs, and constitutes most gland tissue?
epithelial
classes of epithelium:
simple
pseudostratified
stratified
epithelial cell shapes:
squamous
cuboidal
columnar
simple squamous epithelium:
appearance:
single layer of thin cells
nucleus flattened in plane of the cell
looks like a flattened egg where nucleus is the yolk
simple squamous epithelium:
representative locations:
air sacs (alveoli) of lungs
kidney tubules and capsules
inner lining (endothelium) of heart and blood vessels
serous membranes of stomach, intestines
simple squamous epithelium:
functions:
allows rapid diffusion or transport of substances thru membrane
secretes lubricating serous fluid
simple cuboidal epithelium:
appearance:
single layer of square or round cells
spherical, central nuclei
in glands: look pyramidal
some have brush border of microvilli in kidney
some are ciliated in lung
simple cuboidal epithelium:
representative locations:
liver
thyroid
mammary, salivary glands
most kidney tubules
simple cuboidal epithelium:
functions:
absorption and secretion
production of protective mucous coat
movement of respiratory mucus
simple columnar epithelium:
appearance:
single layer of tall, narrow cells
oval or sausage-shaped nuclei
vertically oriented
often has brush border of microvilli, ciliated in some organs
may possess goblet cells
simple columnar epithelium:
representative locations:
inner lining of stomach, intestines, gallbladder, uterus, and uterine tubes
some kidney tubules
simple columnar epithelium:
functions:
absorption, secretion of mucus and other products
movement of egg and embryo in uterine tube
pseudostratified columnar epithelium:
appearance:
looks multilayered, all cells reach basement membrane
nuclei at several levels in deeper half of epithelium
often w/ goblet cells
often ciliated
pseudostratified columnar epithelium:
representative locations:
respiratory tract from nasal cavity to bronchi
portions of male urethra
pseudostratified columnar epithelium:
functions:
secretes and propels mucus
goblet cells (def)
wineglass-shaped cells
produce protective mucous coatings over the mucous membranes
often located in simple columnar and pseudo stratified columnar epithelia
a specialized layer that serves to anchor an epithelium to the connective tissue below is a ___ membrane
basement
the epithelium consisting of one layer of cells in which all cells rest directly on the basement membrane, but appear to be arranged in layers, is ___ epithelium
simple
(pseudo stratified)
the free surface of the epithelial layer describes the ___ surface
apical
stratified squamous epithelium – keratinized:
appearance:
multiple cell layers w/ cells becoming increasingly flat and scaly toward surface
surface covered w/ layer of compact dead cells w/o nuclei
basal cells may be cuboidal to columnar
stratified squamous epithelium – keratinized:
representative locations:
epidermis
palms and soles are especially heavily keratinized
stratified squamous epithelium –keratinized:
functions:
resists abrasion and penetration by pathogenic organisms
retards water loss thru skin
stratified squamous epithelium –nonkeratinized:
appearance:
multiple cell layers w/ cells becoming increasingly flat and scaly toward surface
same as keratinized epithelium but w/o the surface layer of dead cells
basal cells may be cuboidal to columnar
stratified squamous epithelium –nonkeratinized:
representative locations:
tongue, oral mucosa, esophagus, anal canal, vagina
stratified squamous epithelium –nonkeratinized:
functions:
resists abrasion and penetration by pathogenic. organisms
stratified cuboidal epithelium:
appearance:
2 or more layers of cells
surface cells square or round
stratified cuboidal epithelium:
representative locations:
sweat gland ducts
egg-producing vesicles (follicles) or ovaries
sperm-producting ducts (seminiferous tubules) of testis
stratified cuboidal epithelium:
functions:
contribuest to sweat secretion
secretes ovarian hormones
produces sperm
urothelium (def)
AKA transitional epithelium
type of stratified epithelia
unique to the urinary tract
stratified epithelia range from ___ to ___ layers of cells, w/ some cells resting directly on others and only the deepest layers attached to the ___ ___
2 to 20
basement membrane
urothelium:
appearance:
somewhat resembles stratified squamous epithelium, but surface cells are rounded, not flattened
typically 5 or 6 cells thick when relaxed and 2 to 3 cells thick when stretched
cells may be flatter and thinner when urothelium is stretched
some cells have 2 nuclei
urothelium:
representative locations:
urinary tract – part of kidney, bladder, part of urethra
urothelium:
functions:
stretches to allow filling of urinary tract
protects underlying tissues form osmotic damage by urine
most widespread epithelium in the body is ___
stratified squamous epithelium
stratified squamous epithelium:
the deepest layers of cells are ___ to ___and include mitotically active stem cells
their daughter cells push toward the surface and become ___ (more ___) as they migrate farther and upward, until they finally die and flake off. Their loss is called ___
cuboidal
columnar
flatter (more scaly)
exfoliation
what are the 4 types of stratified epithelia?
stratified squamous
stratified cuboidal
stratified columnar epithelia
urothelium (transitional epithelium)
what is the function of transitional epithelium?
to move fluid thru tubules
what are cells that have a square or round shape?
cuboidal
which epithelium is best suited for resisting abrasion and preventing pathogen entry into deeper tissues?
stratified squamous
epithelial cells that have a flat and scaly shape are classified as ___ cells
squamous
which layers w/in a stratified epithelium undergo mitosis?
basal layers
what are the 4 types of stratified epithelia?
stratified columnar
stratified squamous
stratified cuboidal
transitional
where would transitional epithelium be found?
lining the lumen of the urinary bladder
stratified ___ epithelium is the most widespread epithelium of the body
squamous
(covers the skin)
the basal cells of a stratified epithelium undergo ___ allowing more epithelial cells to be produced
mitosis
what is the function of transitional epithelium?
to allow stretching
