Epithelia 1

Question 1

give examples of diseases linked to epithelia

Answer 1

Breast cancer
cystic fybrosis
cholera
atherosclerosis

Question 2

Define epithelial tissue

Answer 2

covers and lines surfaces, tubes and cavities of the body

also form interfaces between different physiological fluid compartments (eg air and blood in lungs)

Question 3

characteristics of epithelial tissue

Answer 3

composed of one or more layers of ceells with very little intercellular space. The layer(s) rest on a basement membrane

Question 4

epithelial tissue differs depending on it’s function. Explain

Answer 4

could diffuse or protect, allow diffusion inwards(), outwards() or both directions ()

Question 5

Define simple epithelia

Answer 5

one layer of cells, all cells are in contact with the lumern and the basement membrane (BM)

Question 6

where is simple epithelia found - linked to function

Answer 6

in sites of the body where there is diffusion, absorption or secretion

Question 7

what happens if the epithelium is very thin?

Answer 7

diffusion or absorption can occur more quickly

Question 8

Stratified epithelia

Answer 8

have multiple layers of cells

Question 9

what are basal cells?

Answer 9

Cells in contact with the basement membrane (BM)

Question 10

what are apical cells?

Answer 10

cells in contact with the lumer

Question 11

where do you find stratified epithelia?

Answer 11

sites on the body where there is need for protection

Question 12

what does a thick epithelium do?

Answer 12

gives more protection from abrasion, infection or caustic content

Question 13

what is caustic content

Answer 13

corrosive content

Question 14

what are the three shapes of epithelial cells?

Answer 14

1 - squamous (blood vessels)
2 - cuboidal (kidney tubules)
3 - columnar (GI tract)

Question 15

name the 4 types of stratified epithelium

Answer 15

stratified squamous - skin
stratified cuboidal - reproductive system
psuedostratified columnar - respiratory
transitional - bladder

Question 16

what are the four classifications?

Answer 16

1- shape of ccells
2- number of layers
3-shape and number of layers
4- function

Question 17

what is useful about rapid regeneration?

Answer 17

damaged, infected cells are not active for long

Question 18

how often are the cells regenerated?

Answer 18

every 4 days they are all replaced (more or less)

Question 19

different functions of epithelilum

Answer 19

exchange (blood vessels, molecules can pass)
transporting (limit movement between cells-does not block)
ciliated (move fluid across a surface)
protective (skin and mouth)
secretory (exocrine and endocrine)

Question 20

what is mesothelium?

Answer 20

epithelium tissue that lines body cavities

Question 21

what are the characteristics of the squamous epithelium?

Answer 21

single layer flattened cells, thin cells, irregular shape, close proximity

Question 22

what is endothelium and what type of epithelium is it?

Answer 22

lining of blood vessels (lumen), single layer squamous

Question 23

function of simple columnar epithelium in small intestine

Answer 23

1) increases surface area for absorption

2) mucus secretion lubricates

Question 24

what are the 3 levels of folding in small intestine and what is the overall function?

Answer 24

function: increase surface area for absorption
1) Large folds
2) Microscopic villi (covered by columnar epithelium)
3) Epithelium cells have microvilli on the surface

Question 25

pseudo stratified columnar epithelium (respiratory is example) have 3 cell types what are they?

(simple columnar has the characteristics in each cell)

Answer 25

1-luminal cilliated cells
2-goblet cells release mucus
3-basal cells (or basement membrane) separates epithelial cells from underlying tissue

Question 26

Desquamation

Answer 26

the shedding of worn off cells from the surface

Question 27

describe STRATIFIED SQUAMOUS EPITHELIUM

characteristic of wet epithelia abrasion not dehydration) ( eg mouth, vagina, anal canal

Answer 27

desquamation on the surface, , basal cells on BM divide and move upwards, protects underlying tissues

Question 28

STRATIFIED SQUAMOUS KERATINISED EPITHELIUM

Answer 28

resists water loss (dry) but subject to abrasion

Question 29

why are there many layers and tight junction in bladder epithelium?

Answer 29

to prevent leakage of urine

Question 30

what is actin?

Answer 30

protein found in epithelial cell junctions, keeps the cell where it should be

Question 31

hemidesmosome?

Answer 31

protein that keeps cell anchored to BM

Question 32

Desmosome?`

Answer 32

attaches two cells

Question 33

list membrane proteins that liink cells to each other

Answer 33

connexin (gap junction)
claudins and occludins (tight junction)
cadherin (adhering junction)

Question 34

name membrane protein that links cell to matrix

Answer 34

integrin

Question 35

what do we mean by resistance of epithelium? what determines it?

Answer 35

how easy it is to get thorugh. type of junctions(?) and number of sealing strands

Question 36

define paracellular movement

Answer 36

absorption and secretion both occur through epithelium

Question 37

list and describe roles of tight junctions

Answer 37

barriers - separate compartments
fences - mantain an asymmetric distribution of lipids and proteins in membranes
gates - selective movement

create compartments with different compositions