Histology of the Epithelium Flashcards
Epithelium that changes its appearance based on the presence of fluid is called?
Transitional Epithelium
Describe the term pseudostratified
Epithelium in which all cells touch the basal membrane, but not all reach the apical surface/lumen.
Multiple layers of epithelial cells is described as…
Stratified
One layer of epithelial cells is described as…
Simple
An epithelial cell that is taller than it is wide is described as…
Columnar
An epithelial cell that is as tall as it is wide is described as…
Cuboidal
A flat epithelial cell is described as…
Squamous
Describe a Goblet Cell.
A specialized unicellular exocrine gland that excretes mucin onto the surface of the epithelium in a mechanism similar to an apocrine gland. Exist in the gut and respiratory tract.
How does an apocrine gland excrete products
The product pinches off the apical surface (top) directly into the lumen.
This gland excretes products via apoptosis once the cell has fully matured.
Holocrine gland
Describe the mechanism of a merocrine gland.
Products are excreted via membrane-bound vesicles.
Name the three types of exocrine glands.
Merocrine, Holocrine, Aprocine
What is the difference between exocrine and endocrine glands?
Exocrine glands release products via a surface duct. Endocrine glands lack a surface duck and release products into the connective tissue to be taken up into the blood stream.
Desmolgeins make up what structure(s)?
Desmosomes/Macula Adherens/Spot Junctions
What structures make up tight junctions?
claudin and occludin
What proteins makes up zonula adherens?
e-cadherin cantenin complex
What is connexin?
The structure that makes up gap junctions.
What is the function of Zonula Occludens?
A tight junction that forms a seal between cells and the lumen, thus restricting fluid movement between cells.
In which domain are gap junctions are present? Why?
Lateral Domain to enable cell-to-cell communication
Name the anchoring junctions of epithelial cells.
Zonula Adherens & Macula Adherens
What structure is impacted by cholera toxins, thus causing diarrhea and dehydration?
Zonula Occludens
This specialized structure is composed of microtubule bundles in a 9+2 arrangement. They extend from the plasma membrane and assist with the movement of substances.
Motile Cilia
This specialize structure is made of long bundled actin. They serve as mechanoreceptors in the inner ear and increase absorption in the epidyimus.
Stereocilia
These specialized extensions are made of actin and serve to increase the surface area of epithelial cells. They are most commonly found in the GI tract and nephron tubules.
Microvilli
What structures are found in the apical domain of epithelial cells?
Microvilli, Cilia, Stereocilia
What are the six characteristics of epithelial tissues?
Derived from all 3 germ layers, Cover all spaces, Regenerative, Undergo Mitosis, Densely Packed - Little interstitial space, Polar - Top, Bottom, Sides
