L8 - Epithelia

Question 1

what does it mean if an epithelial cell has a large nucleus?

Answer 1

it may produce a lot of protein

Question 2

what are epithelial tissues main functions? 2

Answer 2

protective barrier and absorption and secretion

Question 3

what cellular junctions are occluding? where are they found?

Answer 3

tight junctions (zonula occludens), found apically at the cell

Question 4

what cellular junctions are anchoring? 3

Answer 4

zonula adherens, desmosomes, hemidesmosomes

Question 5

what do zonula adherens do?

Answer 5

link cells together by the actin cytoskeleton

Question 6

what do desmosomes do?

Answer 6

anchor cells together

Question 7

what do hemidesmosomes do?

Answer 7

anchor cells to the basement membrane

Question 8

what cellular junctions are for communicating? how so?

Answer 8

gap junctions, allow for small molecules to travel in between the gaps

Question 9

what are zonula occludens (tight junctions) transmembrane proteins?

Answer 9

occludin and claudin

Question 10

what do different claudins cause?

Answer 10

different permeabilities in different tissues

Question 11

what effect does claudin-16 have on the kidney?

Answer 11

makes only specific regions are permeable to Mg2+ ions

Question 12

what effect does a mutation inclaudin-16 gene have on the kidney?

Answer 12

causes abnormal claudin-16 resulting in junction impermeable to ions and so low Mg2+ reabsorption back into the blood

Question 13

what conditions can be caused by mutated or faulty claudins? 3

Answer 13

magnesium deficiency, kidney damage/renal failure, dehydration via skin

Question 14

what is claudin-1 responsible for?

Answer 14

waterproofing qualities of the skin

Question 15

what is zonula adherens (adherens junction) main transmembrane protein?

Answer 15

E-cadherins

Question 16

what disease is linked to the loss of E-cadherins?

Answer 16

metastasis of cancer cells

Question 17

what kind of cancerous cells have lower levels of E-cadherin expression?

Answer 17

malignant

Question 18

desmosomes also called?

Answer 18

macula adherens

Question 19

how do desmosomes anchor cells together?

Answer 19

link cytoskeletons of adjacent cells by connecting cytokeratin (intermediate filaments)

Question 20

what is a desmosomes main transmembrane protein? example?

Answer 20

cadherins e.g. desmoglein

Question 21

what is pemphigus vulgaris?

Answer 21

an autoimmune disease

Question 22

what do antibodies attack if you have pemphigus vulgaris disease?

Answer 22

desmoglein 3

Question 23

what happens to your skin cells when you have pemphigus vulgaris?

Answer 23

cells fall apart, skin sloughs off

Question 24

cadherins are important for…

Answer 24

maintaining structural integrity of epithelium

Question 25

where are hemidesmosomes found in the cell?

Answer 25

basal surface of cell

Question 26

what do hemidesmosomes bind to?

Answer 26

cytokeratin

Question 27

what are hemidesmosomes main transmembrane proteins?

Answer 27

integrins

Question 28

what are gap junctions main transmembrane proteins?

Answer 28

connexins

Question 29

what is a connexon?

Answer 29

when a connexin forms a channel that can open/close to allow passage of ions and small molecules

Question 30

epithelial tissue is polarised and linked as sheets through...

Answer 30

lateral junctions

Question 31

specialisations are linked to ___ of the cell?

Answer 31

polarity

Question 32

what does microvilli provide?

Answer 32

increased surface area

Question 33

what makes up the core of microvilli?

Answer 33

parallel actin bundles

Question 34

what are non-motile cilia function?

Answer 34

sensory information, protection

Question 35

what are motile cilia function?

Answer 35

beat in rhythm to move substances across surface of epithelium

Question 36

example of motile cilia

Answer 36

respiratory tract

Question 37

what is cilia's cytoskeleton composed of?

Answer 37

a core of microtubules

Question 38

what is the basement membranes structural role?

Answer 38

binds epithelial cells to connective tissue

Question 39

both epithelia and connective tissue excrete molecules that come together to form what?

Answer 39

basement membrane

Question 40

what is the basement membrane's structure?

Answer 40

sheet-like arrangement of ECM proteins

Question 41

why does epithelia allow nutrients to pass through?

Answer 41

because epithelia isn't vascularised

Question 42

what does the basement membrane do? 2

Answer 42

regulates permeability, controls growth and direction

Question 43

what three layers of basement membrane can be seen under electron microscopy? how are these layers distinguished?

Answer 43

lamina lucida - quite clear, lucid lamina densa (aka basal lamina) - denser, easer to see lamina fibroreticularis

Question 44

what does basal folding do?

Answer 44

increases surface area on basal surface of cell