adhesion and ecm

Question 1

what are the 6 connective tissue cells?

Answer 1

• fibroblasts
• myofibroblasts
• blood derived products
• osteoblasts
• chondroblasts
• adipocytes

Question 2

what 2 things combine to make polysaccharides?

Answer 2

glycosaminoglycans and specific proteins

Question 3

what is the ecm made from

Answer 3

fibrillar proteins - elastin, collagen, laminin, fibronectin.
GAGS

Question 4

fibroblast function

Answer 4

synthesis and secrete collagen, elastin, proteoglycans

Question 5

why is collagen secretion special?

Answer 5

• because collagen is packaged into specialised large vesicles in the RER.
• secretion occurs by exocytosis at specialised sites.

Question 6

what is the membrane tube that collagen is produced in?

Answer 6

fibropositor

Question 7

where are elastic fibres secreted from?

Answer 7

fibroblasts
smooth muscle cells
chondroblasts

Question 8

how does elastin recoil?

Answer 8

it recoils because of its hydrophobic effect, it wants to recoil when it is stretched because its hydrophobic fibres are exposed to aqueous environment.

Question 9

proteoglycan function?

Answer 9

• matrix support (cushioning/hydration)
• glue like function

Question 10

what will intern attach to?

Answer 10

it is a transmembrane protein that will attach to fibronectin on the outside and an adaptor protein on the inside.

Question 11

describe GAGs

Answer 11

• they are long chains of repeating disaccharide units.
• highly charged and highly hydrated.

Question 12

what does hyaluronic acid do?

Answer 12

it links between the ecm and cytoskeleton. (across the plasma membrane)

Question 13

what will collagen and proteoglycans link too?

Answer 13

fibronectin

Question 14

what are the 2 functions of myofibroblasts?

Answer 14

fibroblast like- secretes collagen
smooth muscle like - synthesises collagen, myosin and desmin.

Question 15

what is myofibroblasts involvement in tissue damage?

Answer 15

• proliferate
• secrete collagen for scaffold
• consolidate damage area (fibrous scar)
• contract (reducing the size of the damaged area)

Question 16

how to myofibroblasts differentiate from fibroblasts?

Answer 16

they have different mechanical tension especially during wound healing.

Question 17

granule content of mast cells?

Answer 17

heparin and histamine

Question 18

plasma cells?

Answer 18

they produce antibodies through the secretory pathway

Question 19

3 functions of adipocytes?

Answer 19

• insulation
• packing
• energy store

Question 20

describe the shape of adipocytes?

Answer 20

they have a large lipid droplet with a peripheral cytoplasm and a squished nucleus.

Question 21

what happens when adipocytes are paraffin embedded during staining?

Answer 21

the lipid will be lost during the processing

Question 22

what can a mutant ob gene cause?

Answer 22

• excessive eating
• obesity

Question 23

in mice with a mutant ob gene are injected with lectin, what happens?

Answer 23

they loose weight as their eating is curbed.

Question 24

leptin

Answer 24

stop eating hormone

Question 25

function of white fat

Answer 25

- energy store but it is extremely dynamic. - produces adipokines (leptin)

Question 26

function of adipokines?

Answer 26

they regulate nutritional balance and other systems.

Question 27

why does leptin increase in fat people?

Answer 27

fat people have more leptin because they have a tissue defect, they have to produce more leptin to get the same response as another person. (resistance to leptin on obesity)

Question 28

what does cell junctions and adhesion proteins do (over all)?

Answer 28

link cells to other cells and to the ecm

Question 29

from top to bottoms, what are the main cell junction?

Answer 29

- tight junctions - adhesion junctions - desmosomes - gap junctions - hemidesmesomes

Question 30

what are the 3 types of cell adhesions cells?

Answer 30

integrin selectin CAM

Question 31

tight junctions

Answer 31

- define polarity as they fence off lipids and proteins - control the passage of substances - can link to actin

Question 32

how does the permeability differ between cells?

Answer 32

because tight junctions are made of claudins (there are 24 different ones) so different Claudins= different permeability of the epithelium.

Question 33

what does adherens junctions do?

Answer 33

they will anchor the actin filaments to the membrane

Question 34

what 2 things will the adherens junction use intracellulary to bind to the actin filament? (anchor proteins)

Answer 34

catenin and vinculins

Question 35

what will adherens junctions use extraceullarly to bind?

Answer 35

cadherin

Question 36

are there different types of cadherin?

Answer 36

yes, each cadherin provides cell adhesion in different tissue.

Question 37

E-cadherin

Answer 37

epithelia

Question 38

N-cadherin

Answer 38

neurons and heart muscle

Question 39

P-cadherin

Answer 39

placenta and epidermis

Question 40

VE-cadherin

Answer 40

endothelial cells

Question 41

desmosomes

Answer 41

they link between strong intermediate filaments in adjacent cells

Question 42

in desmosomes what what do cadherin proteins bind to?

Answer 42

- adjacent cadherin - cell membrane - intracellular plaque glycoprotein

Question 43

hemidesmesomes

Answer 43

- they link the outside of the cell through transmembrane proteins (integrins) to the cytoskeleton (intermediate filaments) - they are more stable than focal adhesions - link laminin to bm

Question 44

symptoms of duchenne muscular dystrophy

Answer 44

muscle weakness muscle wasting damage to muscle fibres due to muscle tearing.

Question 45

treatment for DMD?

Answer 45

PTC 124 (ataluren) though to override the premature stop codon to produce

Question 46

what transition will carcinoma cells undergo?

Answer 46

they will undergo epithelial to mesenchymal transition

Question 47

what happens in micro invasion

Answer 47

- reduced expression of cadherin due to the transition to mesenchymal cells (no longer epithelial) - protrusion called invadopedia - secretion of metalproteases - bm breached - tumour cells express integrin promoting interaction with non epithelial cells during movement.

Question 48

what happens in metastasis?

Question 49

where are gap junctions found

Answer 49

cardiac muscle

Question 49

desmosomes bing to a glycoprotein plaque intracellularly, what is this plaque made of?

Answer 49

desmoplakin plakoglobin

Question 49

function of gap junctions

Answer 49

- communication - make a hydrophilic Chanel - allowing small molecules to pass - coordination of function

Question 49

what is cytoplasmically anchored to the plaque in desmosomes?

Answer 49

keratin filaments

Question 50

what happens during metastasis

Answer 50

- the autocrine motility factors from the tumour increase the motility and decrease E-cadherin - angiogenesis factors promote vasularisation allowing entry into bv and lymphatics

Question 51

duchenne muscular dystrophy

Answer 51

lack of dystrophin adaptor protein due to a nonsense mutation causing the premature termination of translation

Question 51

focal adhesions function

Answer 51

- they link the outside of the cell with the cytoskeleton (actin) via integrin transmembrane proteins. - they can act as signalling platforms.

Question 51

what are the cadherins made of in desmosomes

Answer 51

desmocollins desmogleins

Question 51

what are gap junctions made of

Answer 51

6 connexions (they all have a central hydrophilic pore)