epithelium

Question 1

whats epithelium?

Answer 1

tissues that form body surfaces (internal/external) and line hollow tubes.

Question 2

5 characteristics of epithelial cells?

Answer 2

avascular (no blood vessels)
v little space between cells
oriented/polarised
cells sit on basal lamina
there are strong attachments between cells and their apical surfaces have surface specialisations

Question 3

describe how epithelial cells are polarised

Answer 3

have apical/basal surfaces

Question 4

describe the basal lamina

Answer 4

connective tissue

• usually sticks to basal surface of bottom layer of cells
• can also completely suround cells

Question 5

difference between basal lamina and basement membrane?

Answer 5

basement membrane = basal lamina + fibrous layers underneath

Question 6

what compounds does the basal lamina contain?

Answer 6

contains collagen type IV; laminin (glycoprotein), and heparin sulfate (proteoglycan)

Question 7

what secretes the basal lamina?

Answer 7

epithelial cells

Question 8

role of basal lamina in pathology?

Answer 8

normal epithelial cells dont cross BL; cancer cells do.

Question 9

size of cilia vs microvilli?

Answer 9

10, 1 micron

Question 10

where are cilia found?

Answer 10

on tracheal surface (with goblet cells) or in fallopian tube.

Question 11

what are microvilli made up of?

Answer 11

actin

Question 12

where are microvili found?

Answer 12

top of villi in intestine, in proximal convoluted tubule in kidney

Question 13

function of microvilli?

Answer 13

increases SA and hence absorption of sbstances

Question 14

what are stereocilia?

Answer 14

long, non motile microvilli

Question 15

where are stereocilia found?

Answer 15

epidydimis, sensory hair cell sin the ear

Question 16

structure of simple squamous:

Answer 16

one layer of flat cells; like an egg

Question 17

function of simple squamous and example?

Answer 17

line hollow tubes - eg. endothelium

Question 18

function of simple cuboidal?

Answer 18

lines hollow tubes - eg. kidney tubules

Question 19

function of simple columnar?

Answer 19

lines small and large intestines; reabsorbs food

Question 20

structure of stratified squamous?

Answer 20

many layers of flat cells

Question 21

function of stratified squamous?

Answer 21

lines external body surfaces

Question 22

wet vs dry stratified squamous?

Answer 22

dry has keratinised/cornified/horny layer while wet doesnt.

Question 23

examples of where stratified squamous is found?

Answer 23

Skin cells, buccal cells in cheeks, vaginal canal and cervix; anal canal; oesophagus…)

Question 24

describe pseudostratified epithelium

Answer 24

Looks stratified (nuclei are in different positions, almost looks like different layers) BUT it is actually simple (each cell membrane has a part of its pm sitting on the basement membrane

Question 25

example of pseudostratified epithelium?

Answer 25

tracheal lining

Question 26

describe transitional epithelium

Answer 26

• only found in urinary system
•  Cell types are the same but appear to change shape. If urinary system has urine in it, cells are stretched out (bottom) and if not its not as stretched.

Question 27

define: carcinoma:

Answer 27

cancers of epithelial cells

Question 28

why does a lot of cancer arise at epithelial linings?

Answer 28

because epithelial cells always changing over -> more mitosis -> more likely DNA mutations