Lecture 8: Epithelia Flashcards
(19 cards)
What are the two subsets of epithelia?
Surface such as lining of surface, lumen. GIT, resp. tract etc.
Glandular which are those involved in secretion, whole organ glands etc.
True or false? Epithelia are polar.
True. They have a base and an apical surface.
What are epithelia connected by?
Cell junctions, supported by basement membranes (though, not all).
True or false? Epithelia have a rich vascular supply.
False, they are avascular. The blood has to pass through the extracellular matrix before getting to the surface epithelia.
What 3 cell types are seen in simple epithelia?
Squamous, cuboidal, columnar.
Give an example of squamous cell and a feature of it.
Vascular endothelium, flattened, helps diffusion.
Give an example of a cuboidal cell.
Proximal convoluted tubule or collecting duct of kidney.
Where in a columnar cell do we find its nucleus? Give examples of some columnar cells.
Nucleus normally sits at the base. Find them in the small intestine as microvilli, small and large bowel, vas deferens, fallopian tube, respiratory tract.
What 3 cell types are seen in stratified epithelia? Give examples of each.
Squamous, cuboidal, transitional. Epidermis, exocrine glands, and everything to do with the bladder and peeing respectively.
What makes up the junctional complex? How are they bound? What are their functions?
3 types of intercellular junctions:
Zonula occludens/tight junction. Limits diffusion to cells, binds to other tight junctions discontinuously.
Zonula Adherens/adhering belt have transmembrane proteins within them, namely, a cadherin which links the two cells together. They anchor on a dense area in each respective cell called a plaque.
Macula adherens/Desmosome
True or false, gap junctions are unique to epithelium.
False.
Briefly describe the anchoring system regarding hemidesmosome.
Anchoring plaque (collagen 4, laminin) found in EM of dermis attaches to hemidesmosome. Anchoring fibrils (collagen 3) insert into this attached to basement membrane.
Integrins, which are transmembrane proteins found on the plasma membranes insert into the BM and intermediate filaments from cytosol insert into the integrins.
What are CAM, or cell adhesion molecules? What are their functions and what different types are there?
Transmembrane proteins that link to other CAMs on neighbouring cells/matrix. Involved in cell adhesion, intra/extra cellular communication, movement and differentiation.
Some examples are Cadherins, Integrins, Selections.
What is a mucosa?
The lining of a body passage communicating with exterior such as respiratory tract. Includes smooth muscles such as muscularis mucosae.
What is a serosa?
The lining of pericardial, tunica vaginalis, peritoneal cavities. Comprises of mesothelium and underlying CT.
What are the 4 types of exocrine secretion/cells?
Goblet cells: Mucous secreting cells packed with membrane bound mucous droplets. Nucleus + organelles are displaced basally. Does not stain in H&E.
Serous Acini, which form secretory units known as acinus. Secrete into narrow lumen which are carried away by ducts. It is basophilic at the base and acidophilic at the apex.
Serous secretion is one that contains protein in aqueous medium such as saliva.
Mucous secretion are glycoproteins in aqueous medium such as GIT, cervix etc.
True or false? Goblet cells does not stain in H&E.
True.
How are epithelial cells replaced?
From the base to apex. Can frequently become malignant. Contains cytokeratin intermediate filaments that’s used to identify epithelial phenotype.
True or false? Serous acini are polar.
True, they are basophilic at base, acidophilic at the apex.
