chapter 5 Flashcards
What are the 3 principal characteristics of the cells that make up epithelium?
-closely apposed and adhere to one another/cell junctions
-functional and morphologic polarity/distinct surface domains
-basal surface attached to underlying basement membrane
Why is epithelioid not considered epithelium?
they lack a free surface
Epithelium functions as a ______________________that facilitates or inhibits the passage of specific substances between the exterior environment and the underlying connective tissue compartment.
selective barrier
when epithelium is one cell layer thick
simple
when epithelium has two or more cell layers
stratified
when the width of the epithelial cell is greater than its height
squamous
when the width, depth, and height of the epithelial cell are approximately the same
cuboidal
when the height of the epithelial cell appreciably exceeds the width
columnar
type of epithelium that appears stratified, although some of the cells do not reach the free surface; all rest on the basement membrane
pseudostratified epithelium
a term applied to the epithelium lining the lower urinary tract, extending from the minor calyces of the kidney down to the proximal part of the urethra
transitional epithelium or urothelium
-the epithelial lining of the blood and lymphatic vessels
-consists of highly specialized simple squamous cells that regulate and monitor cellular transport, vascular smooth muscle tone, immune responses, and synthesis and secretion of variety of hormone and active metabolites
endothelium
the epithelial lining of ventricles and atria of the heart
endocardium
the epithelium that lines the walls and covers the contents of the closed cavities of the body
mesothelium
What are the different functions performed by epithelium?
secretion
absorption
transportation
mechanical protection
receptor function
In some pseudostratified epithelia, basal cells are the ___________________that give rise to the mature functional cells of the epithelium, thus balancing cell turnover.
stem cells
Which domain is always directed toward the exterior surface or the lumen of an enclosed cavity or tube?
apical
Which domain communicates with adjacent cells and is characterized by specialized attachment areas?
lateral
Which domain rests on the basal lamina, anchoring the cell to underlying connective tissue?
basal
finger-like cytoplasmic projections on the apical surface of most epithelial cells that increase the free cell surface area
microvilli
In general, the number and shape of the microvilli of a given cell type correlate with the cell’s _________________________.
absorptive capacity
The microvilli of the _____________________epithelium are the most highly ordered and are even more uniform in appearance than those that constitute the brush border of kidney cells.
intestinal
Microvilli contain a conspicuous core of about 20 to 30 __________________.
actin filaments