Epithelium Flashcards
What is the difference between Parenchyma and Stroma?
The parenchyma contains cells responsible for the function attributed to an organ. The stroma consists of cells that have a supporting role in maintenance of the structure (and thus, function) of an organ. Stroma is always connective tissue. Parenchyma and stroma interact on a basic biological level.
Is epithelium classified as parenchyma or stroma?
Parenchyma
What is the stroma that underlies the epithelium of the respiratory, digestive, and urinary systems called?
Lamina Propria
What does the basement membrane regulate?
-Cell adhesion -Cell polarity -Cell differentiaion -Barrier function of the epithelial layer
What are the two layers of the basement membrane?
-Basal Lamina (epithelium) -Reticular Lamina (stroma)
What are junctional complexes used for?
-Cell-cell adhesion -adhesion to the basal lamina -communication
What is the purpose of tight/occluding junctions?
to form seals between adjacent cells
What is the purpose of Adherent/anchoring junctions?
-to permit cells to adhere to one another to resist abrasion -To permit cells to anchor to the basal lamina
What is the purpose of Gap Junctions?
-channels to provide communication between neighboring cells
What is the fancy word for tight junctions?
Zonulae Occludens
What two transmembrane proteins interact to form tight junctions?
-claudin -occludin
What is the fancy word for Adherent junctions which form a belt-like adhesion?
Zonula Adherens
What is the fancy name for adherent junctions that form a spot weld-like adhesion?
Maculae Adherens
Where is the Zonula Adherens located in relation to the Zonulae Occludens?
It is located just below the Zonulae Occludens
What proteins mediate the anchoring of cells together via the zona adherens?
-Cadherins -Catenin
What proteins mediate the anchoring of cells together via the Maculae Adherens?
-Desmoglein and Desmocollin (Cadherins) -Anchor to Plakoglobin and Desmoplakin
What do hemidesmosomes do?
lock down an epithelial cell to the basal lamina of the basement membrane
What do hemidesmosomes bind to in the basal membrane?
-laminin -Type IV collagen
Functions of microtubules:
-a component of the mitotic apparatus -important for cilia and flagella functions -important for intracellular transport of vesicles and organelles
Functions of Microfilaments:
-Cellular movement -cell contractile activity -movement of vesicles (cytoplasmic streaming)
Functions of Intermediate Filaments:
-More stable and intermediate in size -important for differentiated cell function and shape
What structure directs the polymerization of microtubules?
Microtubule Organizing Centers (MTOCs) =Centrosomes
Brush Border
Microvilli on gut epithelial cells
What microfilament is contained in microvilli?
Actin
Where are stereocilia observed?
The absorptive cells of The epididymis and ductus deferens-Sensory hair cells
What is the microtubule arrangement in cilia?
-9:2-9 microtubule doublets and two central microtubules
What is the 9+2 microtubule arrangement in cilia called?
an axoneme
What lies at the base of cilia?What structure is it similar to?
-Basal body -Centriole
What is stratified epithelium?
epithelium that has two or more layers of cells
What is simple epithelium?
epithelium that has only one layer of cells
What kind of cells are in thin epithelium?
squamous
What kind of cells are in cube shaped epithelium?
cuboidal
What type of cells are in tall epithelium?
columnar
Where would I find stratified squamous keratinized epithelium?
Skin
What type of epithelium permits expansion of the surface?What feature allows for this expansion?
-Transitional Epithelium -The presence of umbrella cells, which can stretch or distend
What is the defining feature of Pseudostratified epithelium?Where would I find it?
-Tall and irregular cells which are all attached to The basement membrane. Nuclei are at different levels .-The lining of The upper respiratory tract
What is a Merocrine gland?
A gland that releases product via exocytosis from membrane bound vesicles
What is a Holocrine gland?
A gland that releases product when cells disrupt and lyse
What is an Apocrine gland?
A gland in which the apical end of the cell partitions off and is extruded into the duct, releasing products
What is an example of a holocrine gland?
Sebaceous glands
What is an example of an apocrine gland?
Mammary gland
What tissue performs merocrine secretion?
Pancreas Acinar Cells
