Epithelia Specialization Flashcards
apical surface specialization
- microvilli
- glycocalyx
- cilia
- stereocilia
lateral surface specialization
- zonula occludens
- zonula adherens
- macula adherins (desmosomes)
- gap junctions
basal surface
- hemidesmosomes
- basal lamina
- basal invagination
- basal evagination
microvilli
- where
- size
- resolvability
- shape
- function
- apical surface
- uniform in length
- not resolvable on LM
- striated or brush border
- absorptive/secretory function
glycocalyx
- what
- function
- composition
- cell coat
- adsorbs pancreatic enzymes
- high in glycoproteins
cilia
- function
- appearance
- resolvability
- length in comparison to MV
- composition
- core structure
- motile/coordinated beating
- uneven appearance
- resolvable on LM
- much longer than microvilli
- core of microtubules
- axoneme
primary cilia dyskinesia
- aka
- mechanism (what it affects)
- complications
- immotile cilia syndrome
- heterogenous, usually affecting dyneins
- complications in the lung, ear, and fertility
Kartageners syndrome
- description
- associated complications (not having to do with epithelial components)
- broader involvement of the ciliary defects
- includes sinus inversus, bronchiectasis, and chronic sinusitis
stereocilia
- shape
- length
- connections
- composition
- function
- elongated, non-motile microvilli
- frequently as long as the cell itself (cilia are much shorter)
- often connections between adjacent stereocilia exist (clumping)
- core of actin filaments
- functions: absorption, mechanosensory
terminal bar
appears as a spot on the LM, this is where the lateral specializations reside
zonula occludens
- aka
- regulate
- create
- interations with transmembrane proteins, cytoskeletal proteins, and intracellular peripheral membrane protein complexes
- tight junctions
- regulate apical border seal
- create apical/basolateral domains
- provide a selectively permeable barrier
- tansmembrane: occludin and claudin
- cytoskeletal proteins: actin
- intracellular peripheral: ZO-1 and cingulin
leaky zonulae occlude can lead to
celiac disease (gluten intolerance)
zonulin
- what protein does it target?
- when is it released?
- release loosens tight junctions by dissociating ZO-1
- release is stimulated by gluten and bacterial overgrowth in gut
cholera toxin and zonulin
-releases a zonula occludens toxin which is equivalent to zonulin and leads to fluid release into the gut causing diarrhea
zonula adherens
- classification/dependency
- associated with what cytoskeleton component
- function
- tightness
- Ca dependent intracellular junctions
- has E-cadherin homotypic intercellular linkages
- continuous with actin cytoskeleton
- resist mechanical stress
- transduce signals from adjacent cells and ECM (responds to stretching)
- not nearly as tight as the tight junctions
macula adherins
- aka
- association
- cytoskeleton association
- aka desmosomes
- uses cadherin family membrane proteins (desmogelin, desmocollin)
- has many peripheral membrane proteins (plakoglobulin, desmoplakin)
- links keratin itermediate filaments between cells
- diagnostic plaque and central line on EM
desmoglein is a target for what disease
-cause of impetigo
- auto antibodies in pemphigus
- a serine protease released during staph areas infections causing impetigo
Gap junctions (macula communicans)
- composed of
- facilitates
- pore forming complex comprised of connexins which make up a connection
- facilitates transcellular movement of metabolites, second messengers, and ions
basal lamina
- functions
- composition
- physical support of the epithelia
- may be discontinuous
- comprised of: collagen 4, laminin, and nidogen
- filtration barrier
reticular lamina
- deep in comparison to basal lamina
- type 3 and 7 collagen
basement membrane
-the combination of the basal lamina and the reticular lamina
hemidesmosomes
- function
- links what
- composition
- looks like
- epithelial cell-matrix adhesion
- links keratin intermediate filaments to basal lamina
- comprised of transmembrane (intern, collagen 17) and peripheral membrane (plectin, BP230) proteins
- half of a desmosome
known mutations that cause blistering in different planes
- mutations in collagen 7
- mutations in anchoring filaments
basal infolds
- definition
- function
- full of what
- found where
- infolding of basal plasma membrane
- increases the surface area for resorption
- cells are full of mitochondria in this area
- abundant in kidney tubules and striated ducts
basal outfoldings
- outfolding of basal plasma membrane
- increases the surface area for attachment
