Lecture 2 (Epithelial Tissue) Flashcards
these are transmembrane proteins fused on outer plasma membrane.
tight junctions
These are the contact points between plasma membrane and tissue cells.
cell junctions
These modification of epithelium are projections and a type of organelle seen on the apical surface of epithelial cells. They beat in a coordinated fashion and assists in the movement of material over the epithelial surface in a manner parallel with the surface of the epithelium.
Cilia
are cell surface modifications which increase surface area of a cell without significantly increasing the size of the cell
microvilli
often seen in organs where the epithelium plays a primary role in the absorption of molecules
microvilli
Merocrine Glands (4)
fluid products, sweat glands, salivary glands, pancreas
involves the release of budding vesicles off the epithelial cells into the lumen of the gland
apocrine secretion
apocrine glands (4)
cellular products, mammary glands, portions of cells, ceruminous glands
holocrine glands (3)
secretory products, whole cells, sebaceous glands
involves the death of an entire cell within a gland which subsequently sloughs off and releases content into the lumen of the gland
holocrine
involves the exocytosis of secretory vesicles to the lumen of the gland
merocrine
secrete their products into a duct that then delivers the product to the lumen of an organ or onto the free surface of the epithelium
exocrine glands
secrete their product into the extracellular space where it is rapidly taken up by the blood vascular system
endocrine glands
an invagination or aggregation of epithelium that forms a solid tissue structure; it is from the enfolding of epithelium and subsequent growth in the underlying connective tissue
Glandular Epithelium
covers the free surfaces of the body (internal and external) and cavities
Lining Epithelia
What composes the tissues that line the inside of the mouth, the esophagus and part of the rectum?
Nonkeratinized Squamous Epithelium
Other surfaces that separate body cavities from the outside environment are lined what lining epithelia?
by simple squamous, columnar, or pseudostratified epithelial cells
forms the walls of the pericardium, pleurae, and peritoneum
mesothelium
is a specialized form of epithelium which is the inner lining of blood vessels, the heart, and lymphatic vessels
endothelium
two functions of epithelium
a. They can act as a lining (lining epithelia)
b. Form a secretory structures (glandular epithelium
(formerly called transitional epithelium) is another type of unique epithelium in which cells can change from squamous to cuboidal, depending on the amount of tension on the epithelium
urothelium
In this type of epithelium, taller simple columnar epithelial cells appear to have several nuclei at different heights, giving the appearance of stratification
pseudostratified epithelium
is composed of cells that are wider than their height (flat and wide)
squamous epithelium
is composed of cells whose height and width are approximately the same (cube shaped).
cuboidal epithelium
is composed of cells taller than they are wide
columnar epithelium
Where can we find the stratified epithelium?
In body linings that have to withstand mechanical or chemical insult such that layers can be abraded and lost without exposing the sub-epithelial layers.
Pseudostratified epithelium is located in?
large respiratory airways of nasal cavity, trachea and bronchi
Characteristics of simple columnar
a. found in areas with extremely high secretory activity (as in the inside lining of the stomach), or absorptive activity (as in small intestine)
b. often possess apical modifications such as the microvilli in the small intestine, or cilia found in some areas of the female reproductive tract
How is simple cuboidal different from other classes of simple epithelium?
Its functions include secretion, absorption and excretion that can be seen in tubules of kidneys, and secretory ducts of pancreas and salivary glands
this type is found in lining areas where passive diffusion of gases occur, such as walls of capillaries and alveoli of the lungs
simple squamous
The thinness of the epithelial barrier facilitates easy movement of molecules across into another compartment
simple epithelium
What are the four morphological classifications of epithelial cells?
number of layers, shapes of cell in free surface, function of the epithelium, surface modification
The surface of a cell that faces a lumen or an outside area.
apical
The surfaces of a cell that faces away from a lumen or outside area
basolateral
A organelle and cell modification that manifests as a membrane projection capable of movement.
cilia
A layer of dead cells filled with keratin that form a protective barrier over a layer of cells. Seen with stratified squamous epithelium
cornification
A cell modification that is responsible a cell to cell adhesion resistant to shearing forces to the epithelial layer
desmosomes
A type of simple squamous epithelium that lines in inside of vascular structures.
endothelium
A basic tissue type that typically lines a surface (cavity, lumen or outside surface) or forms glands. plural, epithelia; adjective, epithelial
epithelium
A cell modification that is responsible for the adhesion of a cell to extracellular matrix.
hemidesmosomes
A structural protein and intermediate filament that provides a tough protective quality to some epithelial cell types. Seen with cornified or keratinized epithelium
keratin
A cell modification that manifests as a membrane projection and increases the surface area of a cell.
microvili
A type of columnar epithelium in which the nuclei are arranged in different levels in the cell layer
pseudostratified epithelium
A single layered arrangement of epithelial cells
simple epithelium
A multilayered arrangement of epithelial cells
stratified epithelium
A cell modification that is responsible for cell to cell adhesion
tight junction
A unique type of stratified epithelium capable of stretching that lines a majority of the urinary tract
urothelium
Give the basic characteristics of epithelial tissue (4)
*All epithelial tissue rests on a basement membrane.
*The basement membrane acts as a substrate on which epithelium can attach to as well as grow and regenerate after injuries.
*Epithelial tissues have a nerve supply, but they do not have a blood supply.
*Therefore, epithelia must be nourished by substances diffusing from vascular structures in the underlying tissue
all epithelial cells share the same characteristics (5)
- Close apposition of cells.
- Free surface of epithelial cells is adjacent to the space.
- Basal surface is adjacent to connective tissue.
- Sheets of epithelial cells may be modified into tubes forming glands.
- Absence of blood vessels within epithelial layer
Primary functions of epithelial tissue
protect, absorption, secretion of hormones, sensory functions
