Ctb 9: Cell Junctions

Front 1

Describe the characteristics of epitheial tissue structure

Back 1

polarized with apical (towars lumen), basal (towards basal lamina), and lateral surfaces, avascular, rest on basement membrane

Front 2

Describe how epithelia are characterized based on the number of cellular layers

Back 2

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

Front 3

How might one disthinguish between a pseudostratified epithelium and a stratified epithelium

Back 3

-Each cell in the pesudo touches the BM, -stratified is never cilliated

Front 4

how are epithelia characterized based on the shape of the cell

Back 4

1. squamous-flat 2. cuobid-cube shape 3. columnar

Front 5

in a stratified epithelium, which cell should you look at to determine the name of the shpae

Back 5

the cells in the most superficial layer

Front 6

Describe the processes of keratinization

Back 6

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

Front 7

what is the glycocalyx

Back 7

carbohydrate rich complex on the extracellular surface of epithelial cells, functions in cellular protection and recongition

Front 8

Describe the structure of cilia

Back 8

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

Front 9

what is an axoneme

Back 9

the 9+2 MF arrangement characteristic of cilia (9 outer doubles and a two central microtubules)

Front 10

Describe the structure of microvilli (filaments)

Back 10

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.

Front 11

Whre are tight junctions (zonula cculdens) located

Back 11

at the intercellualr juctions near the apical surface of the cell

Front 12

what is the function of the zonula occludens (tight junction)

Back 12

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

Front 13

Describe the chaceristic features of tight junctions (zonula occludens) on EM

Back 13

pentalaminar dark-light-dark-light-dark apperance cause dby fusion of the outer membranes of the lipid bilayers of two adjacent cells

Front 14

Describe the proteins invovled with tight junction structure

Back 14

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

Front 15

where is the zonula adherens (adherens junction) located

Back 15

just beaneath the zonual occuldens

Front 16

What are the three components of the zonula adherens

Back 16

1. transmembrane linker proteins (cadherin) 2. sub-plasmalemmal plaque proteins (catenins, -actinin, vinculin) 3. cytoskeletal filaments (actin microfilaments)

Front 17

Describe the structure of the macula adherens (desmosome). What proteins are invovled

Back 17

"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

Front 18

describe the structure of gap junctions

Back 18

two connexons one in each of the adjoining cells each of which is made up of 6 subunits (juction has 12 connexin molecules total)

Front 19

Hemidesmosomes are a basal membrane specialization. Describe their structure

Back 19

half, desmosomes, integrins attach cell to the ECM components such as laminin, collagen, and fibronectin

Front 20

Adhesion plaques are a basal membranes specialization, describe their structure

Back 20

link to the ECM via integrins, similar to ozna adherens in that their plaque contains actinin and veniculin which in turn attaches to microfilaments

Front 21

define junctional complex

Back 21

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

Front 22

what is the difference between a carcinoma and and adenocarcinoma

Back 22

carcinoma=malignant tumor of epithelial cells, adenocarinoma=malignant tumor of epithelial glandular cells

Front 23

How could you stain to tell whether a tumor was epithelial, glial, muscle, or CT origin

Back 23

epithelial=keratin, glial=GFAP, muslce=desmin, CT=vimentin

Front 24

what cytoskeletal filaments interact with zonula occludens (tight jucnctions)

Back 24

actin microfilaments

Front 25

what cytoskeletal filaments interact with zonula adherens (adherens junction)

Back 25

actin microfilaments

Front 26

what cytoskeletal filaments interact with macula adherens (desmosomes)

Back 26

intermediate filaments (keratin)

Front 27

what cytoskeletal filaments interact with adhesion plaques on the basement membrane

Back 27

actin microfilaments

Front 28

t/f gap junctions ineract with the cytoskeleton

Back 28

false, there is no cytoskeletal protein associated with connexons

Front 29

what are the plaque components of zonula occludens (tight junctions

Back 29

ZO's 1-3

Front 30

what are the plaque components of teh zonula adherens

Back 30

<-actinin, vinculin

Front 31

what are the plaque components of hemidesomsomes

Back 31

desmoplakin-like

Front 32

what are the plaue components of macula adherens (desmosomes)

Back 32

desmoplakin, plakoglobin, plakophilin

Front 33

what are the plaque proteins associated with gap junctions

Back 33

none

Front 34

What is the transmembrane linker protein of zonula occuludens

Back 34

claudins, occludin, JAM

Front 35

What is the transmembrane linker protein of zonula adherens

Back 35

cadherin

Front 36

what is the trnasmembrane linker protein of macula adherens (desmosomes)

Back 36

desmogelin, desmocollin

Front 37

What is the transmembrane linker protien of hemidemosomes

Back 37

integrin

Front 38

what is the transmembrane linker protien of adhesion plaques

Back 38

integrin

Front 39

what is the transmembrane linker protein of gap junctions

Back 39

connexin

Front 40

What is the functional type of zonula occludens

Back 40

occulding juction

Front 41

what is the functional type of zonula adherens

Back 41

anchoring junction

Front 42

what is the functional type of macual adhernes

Back 42

anchoring junction

Front 43

what is the functional type of hemidesmosomes

Back 43

anchoring junction

Front 44

what is the functional type of gap junctions

Back 44

communicationg junction