epithelia

Question 1

what are the 4 basic tissue types of organs

Answer 1

epithelium
connective tissue
muscle
nervous tissue

Question 2

what are epithelia composed of

Answer 2

closely aggregated, polyhedral epithelial cells with a minimum of intercellular substance

Question 3

adhesion between epithelial cells is
A. strong
B. weak

Answer 3

A. strong

thus cellular sheets are formed which are able to cover exposed external surfaces and line internal cavities

Question 4

what does the epithelial form

Answer 4

the outer protective layer of the skin

Question 5

epithelia are usually polarized

Answer 5

yes

Question 6

all epithelial cells have a sheet like structure composed of extracellular matrix components called what

Answer 6

basal lamina (basement membrane)

Question 7

epithelial cells are described as non vascular, what does this mean

Answer 7

nutrients from capillaries in underlying tissue must diffuse across the basal lamina

Question 8

epithelial cells tend to bind together in what form

Answer 8

sheets

Question 9

what are some functions of the epithelia

Answer 9

mechanical barrier (skin)
chemical barrier (lining of stomach)
absorption (lining of intestine)
secretion (salivary gland)
containment (lining of urinary bladder)
locomotion (by cilia - oviduct)

Question 10

the role ofthe epithelium determines its what

Answer 10

type and structure

Question 11

two types of cellular components that are vital to the function of epithelia in the care

Answer 11

• cytoskeleton (maintains cellular integrity)

- intercellular junctions(links cells together into a functional unit)

Question 12

what are the three main classes of filaments that form the cytoskeleton of cells

Answer 12

microfilaments
intermediate filaments
microtubules

Question 13

what is the diameter of the microfilament

Answer 13

5nm

Question 14

what is the diameter of the intermediate filament

Answer 14

10nm

Question 15

what is the diameter of microtubules

Answer 15

25

Question 16

how do filaments become attached to cell membranes and to each other and what does this form

Answer 16

by anchoring and joining proteins to form a dynamic 3 - dimensional internal scaffolding in the cell

Question 17

the fine strands of what protein make up microfilaments

Answer 17

actin

Question 18

what are the functions of microfilaments

Answer 18

anchorage, movement and extension of cell membrane

Question 19

under which structural feature are actin filaments located

Answer 19

cell membrane

Question 20

in microfilaments, what does globular actin polymerize to form

Answer 20

filamentous actin

Question 21

what do intermediate filaments bind together

Answer 21

bind intracellular elements and then binds this to the plasmalemma

Question 22

intermediate filaments are not as dynamic as what

Answer 22

microfilaments and microtubules

Question 23

what two subunits are microtubules composed of

Answer 23

alpha and beta in an alternating array

Question 24

microtubules can be described as

Answer 24

assembled and disassembled

Question 25

what are microtubules important in

Answer 25

movements of components in the cell and in cell division (from the spindle apparatus)

Question 26

intercellular junctions are specialised structures which link what

Answer 26

individual cells together into a functional unit

Question 27

what are the 3 types of intercellular junctions

Answer 27

occluding junctions anchoring junctions communicating junctions

Question 28

what's the role of an occluding junction

Answer 28

links cells to form a diffusion barrier

Question 29

what's the role of an anchoring junction

Answer 29

provides mechanical strength

Question 30

what's the role of a communicating junction

Answer 30

allows movement of molecules between cells

Question 31

what effect does an occluding junction have on diffusion

Answer 31

it inhibits diffusion

Question 32

occluding junctions appear as a focal region of close apposition between what

Answer 32

adjacent cell membranes

Question 33

in occluding junctions, what is another name for a tight junction

Answer 33

zonula occludens

Question 34

in an anchoring junction, what is the role of an adherent junction

Answer 34

links submembrane actin bundles of adjacent cells

Question 35

what is another name for adherent junctions

Answer 35

zonula adherens

Question 36

what transmembrane molecule bind to eachother in the extracellular space, and, through link molecules, to actin of the cytoskeleton

Answer 36

cadherin

Question 37

what do desmosomes link and what is the name of the function

Answer 37

links submembrane intermediate filaments of adjacent cells | called macula adherens

Question 38

what role do desmosomes provide in the skin

Answer 38

provide mechanical stability

Question 39

what do communicatice junctions allow

Answer 39

selective diffusion of small molecules and ions between adjacent cells

Question 40

where are communicative junctions found

Answer 40

epithelia smooth muscle cardiac muscle

Question 41

what is a junctional complex

Answer 41

close association of several types of junctions found in certain epithelial tissues

Question 42

covering epithelia are based on what

Answer 42

cell shape the number of layers of cells cell surface, tissue surface, specializations presence of any specialized cell types

Question 43

``` if a cell were to be described as A. squamous B. cuboidal C. columnar, what would this be describing ```

Answer 43

A. flattened, like a fish scale B. cube shaped C. like a column, tall and thin

Question 44

``` if a cell were to be described as A. simple B. stratified C. pseudostratified, what would this be describing ```

Answer 44

A. one layer B. two or more layers C. tissue appears to have multiple layers, but in fact all cells are in contact with the basal lamina

Question 45

what are some specializations of cell surface or tissue surface

Answer 45

- prominent microvilli - cilia - kertinized (presence of layers of keratin proteins on the tissue surface)

Question 46

what are goblet cells

Answer 46

single cell mucous glands

Question 47

what is the role of microvili in epithelia

Answer 47

serves to increase the surface area of the cell membrane

Question 48

what are the length of microvili

Answer 48

0.5-1um

Question 49

how long are motile cells

Answer 49

10um long

Question 50

what is the purpose of motile cells

Answer 50

serve to propel mucous or fluid over the cell surface

Question 51

what structures can be seen within cilia

Answer 51

core of microtubules

Question 52

what are keratins

Answer 52

groups of tough structural proteins