Epithelium Flashcards
Chapter 2
Define Tissues
groups of cells similar in structure and function.
What are the 4 main tissue types
epithelium, connective, muscular, nervous
describe function of Epithelium in one word
Covering
describe function of connective in one word
support
describe function of muscular in one word
movement
describe function of nervous in one word
control
organs are usually made up of how many tissue types
two or more
Define Epithelium
it is the lining, covering, and glandular tissue of the body.
Describe glandular epithelium briefly
forms various glands in the body
Describe lining covering epithelium briefly
lines and covers entire free body surface and contains versatile cells.
give two example of lining covering epithelium
one type forms the epidermis the outer layer of the skin and others dip into the body to line its cavities.
how does epithelium form boundaries
it is a barrier from the outside world and nearly all substances the body gives off and receive must pass through the epithelium.
main function of epithelium is
protection, absorption, secretion, and filtration.
how epithelium serves as protection
the epithelium of the skin protects against bacterial and chemical damage.
epithelium lining the respiratory tract sweeps dust and debris away from the lungs.
how epithelium serves as absorption
Epithelium specialized to absorb substances lines some digestive system organs such as the stomach and small intestine, which absorb food nutrients into the body.
how epithelium serve as filtration
in the kidney’s epithelium both absorbs and filtrates.
secretion is specialty of what
glands
what are some examples of substances produced by glands
oils, perspiration, digestive enzymes, and mucus
what are the main characteristic of epithelium
- has an apical surface and a basement membrane
- fit closely together and form continuous sheets
- some surfaces are slick other are modified
- a vascular
- if well nourished can regenerate easily
in epithelium Neighboring cells are
bound together at many points by what
specialized cell junctions, including desmosomes and tight junctions
describe apical surface
the membranes free (unattached) surface or edge
the apical surface is exposed to what
the body’s exterior or the cavity of an internal organ
the exposed surface can be two things
slick and smooth or modified
example of modifiers apical surface of epithelium may exhibit
cilia and and micro villi
where does the lower surface of an epithelium sit on
basement membrane
what is the basement membrane
a structure less material secreted by both the epithelial cells and the connective tissue cells that abut the epithelium
how does the epithelium get nutrients and o2
depend
on diffusion from the capillaries in the underlying connective tissue for food and oxygen
can epithelium regenerate
yes, if well nourished
classification of epithelium in terms of cell layers
simple meaning one layer of cells and stratified meaning more than one layers of cells.
classification of epithelium in terms of shape
squamous - flattened like fish scales
Cuboidal - shaped like dice / cubes
Columnar - shapes like columns
the cells at the free surface of the epithelium membrane are
stratified epithelium
simple epithelium is most involved in
absorption, secretion, and filtration
why is protection not a specialty of simple epithelium
because it is very thing and one layered in terms of cells
which epithelium fit closely together like floor tiles
simple squamous epithelium
what type of activity occurs in simple squamous epithelium
membrane were filtration by rapid diffusion occurs like in the air sacs of the lungs and walls of capillaries
what specific membrane simple squamous epithelium forms
serous membrane
define serous membranes
slick membranes that line the ventral body cavity and covers the organs in it
simple cuboidal epithelium is usually common in what
glands and their ducts (salivary glands and pancreas)
covers the surface of the ovaries
forms the walls of the kidney tubules
simple columnar epithelium has what type of cells
goblet cells
what are goblet cells
cells that produce lubricating mucus
simple columnar epithelium is found where
lining the entire length of the digestive tract from stomach to anus.
specific membrane in simple columnar epithelium
mucosae membrane
define mucosae membrane
Epithelial membranes that line body cavities open to the body exterior
why is it called Pseudostratified
some of its cells are shorter than others,
and their nuclei appear at different heights above
the basement membrane. As a result, this epithelium
gives the false (pseudo) impression that it is stratified; hence its name
pseudostratified ciliated columnar epithelium found where
lines most of the respiratory tract
how does the mucus produced by goblet cells relate to cilia
The mucus produced by the goblet cells in this epithelium traps dust and other debris, and the cilia propel the mucus upward and away from the lungs
stratified epithelia primary function is
protection
why can stratified epithelia protect
more cell layers therefore more durability
what is the most common stratified epithelium
stratified squamous epithelium
describe stratified squamous epithelium
It usually consists of several layers of cells. The cells at the free edge are squamous cells, whereas those close to the basement membrane are cuboidal or columnar.
where is stratified squamous epithelium found
in sites that receive a good deal of abuse or friction,
such as the esophagus, the mouth, and the outer
portion of the skin
describe stratified cuboidal epithelium
typically has just two cell layers with (at least) the surface cells being cuboidal in shape
describe stratified columnar epithelium
surface cells are columnar and cells in the basal area vary in shape and size
which epithelium is rare in the body and where can they be found
stratified columnar and cuboidal epithelium and can be found in ducts of large glands.
which stratified epithelium is highly modified
transitional epithelium
transitional epithelium is actually what
highly modified, stratified squamous epithelium
why is transitional epithelium found in organs of the urinary system give examples
the urinary bladder, the ureters, and part of the urethra.
All these organs are part of the urinary system and
are subject to considerable stretching
transitional epithelium basal cells are what shaped
cuboidal or columnar
transitional epithelium free surface cells are what shaped
vary in appearance
when the organ is not streched describe it
the membrane is many layered and superficial cells are rounded and domelike
when the organ is streched describe it
epithelium thins and surface cells flatten and become squamous like.
how is transitional epithelium convinient for urinary bladder and ureters
This ability of transitional cells to slide past one another and change their shape (undergo “transitions”) allows the ureter wall to stretch as a greater volume of urine flows through that tube like organ. In the bladder, it allows more urine to be stored.
gland
consists of one or more cells that make
and secrete a particular product
what is the product of gland called
This product, called a secretion,
the secretion is made up of what
typically contains protein molecules in an aqueous (water-based) fluid.
the term secretion can also indicate what
The term secretion also indicates an active process in which the glandular cells obtain needed materials from
the blood and use them to make their secretion,
which they then discharge
two major glands are
endocrine and exocrine
which gland is ductless
endocrine
which gland releases through ducts
exocrine
describe how secretions of endocrine glands are released
diffuse directly into the blood vessels that
weave through the glands.
example of endocrine glands
adrenal, thyroid, and pituitary
example of excorine glands
sweat and oil glands
which organs are both internal and external
pancreas and liver
