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44 Cards in this Set
- Front
- Back
Describe the characteristics of epitheial tissue structure
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polarized with apical (towars lumen), basal (towards basal lamina), and lateral surfaces, avascular, rest on basement membrane
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Describe how epithelia are characterized based on the number of cellular layers
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1. simple= single layer 2. stratified=two more layers, only basal layer contacts BM (transitional epithelium is stratifed but apparent number of cell layers changes) 3. Pseudostratified=appears to have more than one layer but all cells contact the BM
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How might one disthinguish between a pseudostratified epithelium and a stratified epithelium
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-Each cell in the pesudo touches the BM, -stratified is never cilliated
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how are epithelia characterized based on the shape of the cell
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1. squamous-flat 2. cuobid-cube shape 3. columnar
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in a stratified epithelium, which cell should you look at to determine the name of the shpae
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the cells in the most superficial layer
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Describe the processes of keratinization
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the outermost surface of a stratified epithelium becomes covered by the IF protein keratin rather than living cells, during maturation the cells acculuate keratin and lose their nuclei, the process provides a tough, water-resistant, non-living surface to protect the underyling tissue
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what is the glycocalyx
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carbohydrate rich complex on the extracellular surface of epithelial cells, functions in cellular protection and recongition
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Describe the structure of cilia
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anchored in a basal body/ centriole which contains nine triplets of MTs, from each basal body, nine doublets of peripheral MTs with dynein arms as well as two central MTs project outward into the cell membrane to form the projection, the 9+2 arrangement is called an axoneme
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what is an axoneme
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the 9+2 MF arrangement characteristic of cilia (9 outer doubles and a two central microtubules)
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Describe the structure of microvilli (filaments)
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each microvillus contains actin microfilaments cross linked by villin that connect to a terminal web consisting of actin and spectin moleclues and intermediate filaments. Actin bundels are attached to the lateral plasma membrane via myosin and calmodulin.
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Whre are tight junctions (zonula cculdens) located
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at the intercellualr juctions near the apical surface of the cell
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what is the function of the zonula occludens (tight junction)
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forms a selectivley permeable barrer that surrounds each cell such that only water and small molecules are able to pass between cells, crucial to coerce transcellular rasnport across polarized cells instead of paracellualr transport between the cells
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Describe the chaceristic features of tight junctions (zonula occludens) on EM
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pentalaminar dark-light-dark-light-dark apperance cause dby fusion of the outer membranes of the lipid bilayers of two adjacent cells
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Describe the proteins invovled with tight junction structure
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transmembrane tight junction proteins such as occludin, claudins, and JAM regulate the passage of solute molecues at the cell:cell interface, ZO proteins (specialized proteins in the sub-plasmalemmal plaque) facilitate the interaction of tight junction transmembrane proteins with the actin cytoskeleton
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where is the zonula adherens (adherens junction) located
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just beaneath the zonual occuldens
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What are the three components of the zonula adherens
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1. transmembrane linker proteins (cadherin) 2. sub-plasmalemmal plaque proteins (catenins, -actinin, vinculin) 3. cytoskeletal filaments (actin microfilaments)
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Describe the structure of the macula adherens (desmosome). What proteins are invovled
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"spot weld" does not encircle cell, transmembrane linker proteins=nonclassical cadherin called desmogleins and desmocollins, the plaque contains desmoplakin, plakoglobin, and plakophilin, the intermediate filametn attached to the desomesome is keratin
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describe the structure of gap junctions
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two connexons one in each of the adjoining cells each of which is made up of 6 subunits (juction has 12 connexin molecules total)
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Hemidesmosomes are a basal membrane specialization. Describe their structure
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half, desmosomes, integrins attach cell to the ECM components such as laminin, collagen, and fibronectin
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Adhesion plaques are a basal membranes specialization, describe their structure
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link to the ECM via integrins, similar to ozna adherens in that their plaque contains actinin and veniculin which in turn attaches to microfilaments
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define junctional complex
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the term applied to the group of cell membrane specializations along the lateral surface of epithelial cells inlcuding the zonula occludnes, zonula adherens, and macula adherens
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what is the difference between a carcinoma and and adenocarcinoma
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carcinoma=malignant tumor of epithelial cells, adenocarinoma=malignant tumor of epithelial glandular cells
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How could you stain to tell whether a tumor was epithelial, glial, muscle, or CT origin
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epithelial=keratin, glial=GFAP, muslce=desmin, CT=vimentin
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what cytoskeletal filaments interact with zonula occludens (tight jucnctions)
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actin microfilaments
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what cytoskeletal filaments interact with zonula adherens (adherens junction)
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actin microfilaments
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what cytoskeletal filaments interact with macula adherens (desmosomes)
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intermediate filaments (keratin)
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what cytoskeletal filaments interact with adhesion plaques on the basement membrane
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actin microfilaments
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t/f gap junctions ineract with the cytoskeleton
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false, there is no cytoskeletal protein associated with connexons
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what are the plaque components of zonula occludens (tight junctions
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ZO's 1-3
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what are the plaque components of teh zonula adherens
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<-actinin, vinculin
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what are the plaque components of hemidesomsomes
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desmoplakin-like
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what are the plaue components of macula adherens (desmosomes)
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desmoplakin, plakoglobin, plakophilin
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what are the plaque proteins associated with gap junctions
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none
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What is the transmembrane linker protein of zonula occuludens
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claudins, occludin, JAM
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What is the transmembrane linker protein of zonula adherens
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cadherin
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what is the trnasmembrane linker protein of macula adherens (desmosomes)
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desmogelin, desmocollin
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What is the transmembrane linker protien of hemidemosomes
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integrin
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what is the transmembrane linker protien of adhesion plaques
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integrin
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what is the transmembrane linker protein of gap junctions
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connexin
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What is the functional type of zonula occludens
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occulding juction
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what is the functional type of zonula adherens
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anchoring junction
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what is the functional type of macual adhernes
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anchoring junction
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what is the functional type of hemidesmosomes
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anchoring junction
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what is the functional type of gap junctions
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communicationg junction
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