epithelium Flashcards

1
Q

whats epithelium?

A

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

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2
Q

5 characteristics of epithelial cells?

A
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
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3
Q

describe how epithelial cells are polarised

A

have apical/basal surfaces

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4
Q

describe the basal lamina

A

connective tissue

  • usually sticks to basal surface of bottom layer of cells
  • can also completely suround cells
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5
Q

difference between basal lamina and basement membrane?

A

basement membrane = basal lamina + fibrous layers underneath

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6
Q

what compounds does the basal lamina contain?

A

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

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7
Q

what secretes the basal lamina?

A

epithelial cells

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8
Q

role of basal lamina in pathology?

A

normal epithelial cells dont cross BL; cancer cells do.

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9
Q

size of cilia vs microvilli?

A

10, 1 micron

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10
Q

where are cilia found?

A

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

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11
Q

what are microvilli made up of?

A

actin

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12
Q

where are microvili found?

A

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

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13
Q

function of microvilli?

A

increases SA and hence absorption of sbstances

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14
Q

what are stereocilia?

A

long, non motile microvilli

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15
Q

where are stereocilia found?

A

epidydimis, sensory hair cell sin the ear

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16
Q

structure of simple squamous:

A

one layer of flat cells; like an egg

17
Q

function of simple squamous and example?

A

line hollow tubes - eg. endothelium

18
Q

function of simple cuboidal?

A

lines hollow tubes - eg. kidney tubules

19
Q

function of simple columnar?

A

lines small and large intestines; reabsorbs food

20
Q

structure of stratified squamous?

A

many layers of flat cells

21
Q

function of stratified squamous?

A

lines external body surfaces

22
Q

wet vs dry stratified squamous?

A

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

23
Q

examples of where stratified squamous is found?

A

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

24
Q

describe pseudostratified epithelium

A

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

25
example of pseudostratified epithelium?
tracheal lining
26
describe transitional epithelium
- 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.
27
define: carcinoma:
cancers of epithelial cells
28
why does a lot of cancer arise at epithelial linings?
because epithelial cells always changing over -> more mitosis -> more likely DNA mutations