Epithelium Flashcards
What are the 3 main characteristics of epithelium cells?
- closely adhere to each other
- structural and functional polarity
- selective barrier
Where is simple squamous epithelium found?
endothelium (lines blood vessels)
mesothelium (lines body cavities)
alveoli in lungs
Where is simple cuboidal epithelium found?
ovary
kidney tubules
small ducts of glands
Where is simple columnar epithelium found?
GI
Where is transitional epithelium found?
urinary tract and renal system
Where is pseudostratified ciliated columnar epithelium found?
trachea and efferent ductules
What are the 5 main epithelial functions?
secretion, absorption, transport, protection, and receptor function
epithelia involved with absorption or secretion are usually what type?
simple or pseudostratified
Simple squamous epithelium have a high rate of what?
transport
stratification of epithelium usually does what to the permeability?
makes it impermeable
Where is the apical domain of the cell?
directed toward the exterior surface
Where is the lateral domain?
communicates with adjacent cells
Where is the basal domain?
rests on the basal lamina
what are stereocilia?
really long immotile microvilli
What is the anatomy of a microvilli?
contains actin filaments that are anchored at the top by a villin and at the bottom by the terminal web (also actin); Myosin 1 binds the actin to the PM of the microvilli
What is the anatomy of a stereocilia?
long actin filaments crosslinked with fimbrin; Their PM is associated with erzin; they have a stem portion that contains alpha-actinin (hair cells lack both erzin and alpha-actinin)
What is the anatomy of a cilia
organized core of microtubules in a 9 +2 pattern; arms contain ciliary dynein for motor that uses ATP
What is the zonula adherens?
encircles the cell and allows adhesion of one cell to another
What is the zonula occludens?
forms a band or seal that completely encircles the cell and prevents flow of material
What is the unit of a gap junction?
6 connexins make up a connexon
What can cause congenital deafness?
mutation in CX-26 gap junctions
what is a hemidesmosome?
found at the contact zone of epithelial cells and the basal lamina and is 1/2 of a desmosome
What is bullous pemphigoid?
disease where Ab is directed toward protein in hemidesmosomes; triggers mast cells to release eosinophil chemotactic factor (ECF) that attracts eosinophils which break down the hemidesmosome and your skin falls off
