Rachael Curry

Question 1

epithelia =

Answer 1

cells that cover / line all body surfaces, tubes, and cavities
also form INTERFACES between different physiological fluid compartments
eg (1)- skin between body tissues and environment
eg(2)- vessel wall between blood and tissues

Question 2

examples of abnormal epithelial function =

Answer 2

1) cystic fibrosis - defective epithelial Cl- ion transport
2) cholera - over-active Cl- ion transport in gut (Cl- leaves –> Na+ leaves –> water follows –> diarrhoea and dehydration)
3) breast cancer - over-proliferation of epithelial cells (NOTE- cancers derived from ep. = CARCINOMAS)

Question 3

structural classifications of epithelia

Answer 3

columnar
cuboidal
squamous

Question 4

columnar =

Answer 4

tall cells

big barrier to transport (large surface area to diffuse through)

Question 5

cuboidal =

Answer 5

boxy cells

fair barrier to transport

Question 6

squamous =

Answer 6

flattened cells

little barrier to transport

Question 7

simple =

Answer 7

1 layer of cells
all cells in contact with lumen and basement membrane
found in sites of body where diffusion / absorption / secretion occur (gut / lungs / blood vessels / etc.)

Question 8

stratified =

Answer 8

multiple layers of cells
cells in contact with lumen = apical
cells in contact with BM = basal
found in sites of body that require protection (mouth / skin / stomach / etc.)

Question 9

basal vs. apical

Answer 9

basal is inferior to apical
basal = closer to basement membrane
apical = closer to lumen

Question 10

simple squamous

Answer 10

single layer of flattened cells
gas exchange/ easy transport
eg- in blood vessel walls

Question 11

functions - exchange

Answer 11

1 cell layer
squamous cells
pores between cells
eg- in lungs and blood vessels

Question 12

functions - transportation

Answer 12

1 cell layer
cuboidal/columnar cells
tight junctions limit movement between cells
eg- in intestines/kidney

Question 13

functions - ciliated

Answer 13

1 cell layer
cuboidal/columnar cells
cilia move fluid across apical surface
eg- in trachea/reproductive system

Question 14

functions - protective

Answer 14

many cell layers
squamous on apical surface / polygonal on basal
tightly connected by DESMOSOMES
eg- in skin/mouth

Question 15

functions - secretory

Answer 15

1 or more cell layers
columnar/polygonal cells
contain extensive (R)ER
eg- in endocrine / exocrine tissues

Question 16

simple squamous

Answer 16

single layer of flattened cells
gas exchange / line body cavities
eg- in blood vessel walls (endothelium) / serous membranes (mesothelium)

Question 17

simple columnar

Answer 17

single layer of cells
increase surface area for absorption
eg- in gastrointestinal tract

Question 18

pseudo-stratified ciliated columnar

Answer 18

appearance of stratified BUT all cells in contact with BM and lumen
modified with cilia to facilitate function
eg- in respiratory tract

Question 19

stratified squamous

Answer 19

many layers of cells
rapidly-dividing basal cells
protect underlying tissues from abrasion
eg- lining of oesophagus

Question 20

keratinised stratified squamous

Answer 20

many layers of cells
resists water loss
subject to abrasion
eg- skin

Question 21

types of trans-cellular movement

Answer 21

absorption

secretion

Question 22

absorption

Answer 22

lumen —> apical compartment –diffusion etc.–> basal compartment = absorption

Question 23

secretion

Answer 23

basal compartment –active transport–> apical compartment —> lumen —> blood/gland/etc. = secretion

Question 24

paracellular movement

Answer 24

molecules move through junctions rather than the cell itself

relies upon diffusion OR active transport

Question 25

gap junctions

Answer 25

function = communication
cell-cell junction
membrane proteins = CONNEXIN

Question 26

types of cell junctions

Answer 26

gap
tight
adhering
(hemi)desmosomes

Question 27

adhering junctions

Answer 27

function = anchoring
cell-cell junction
membrane protein = CADHERIN

Question 28

desmosomes and hemidesmosomes

Answer 28

Desmosomes
function = anchoring
cell-cell junction
uses CADHERIN and INTERMEDIATE FILAMENTS

Hemidesmosomes
function = anchoring
cell-matrix junction
membrane protein = INTEGRIN or KERATIN
ECM protein = LAMININ

Question 29

ROLE of tight junctions

Answer 29

BARRIERS
separate compartments
protective (sealing strands increase resistance against movement)
eg- urinary bladder

FENCES
maintain asymmetric distribution of lipids and proteins between apical / basal membranes
creates compartments w/different chemical compositions - localises receptors
eg- gastrointestinal tract

Question 30

stratified cuboidal

Answer 30

multiple layers of cells

eg- in reproductive system (RARE)

Question 31

Functional difference between epithelial and non-epithelial cells

Answer 31

non-ep = no way to orientate cells (no up/down)
whereas
ep = maintain a polarity (due to junctions) that orientates the cell layer