Ecm L9

Question 1

How is the basal lamina different in muscle compared to epithelial cells

Answer 1

It surrounds it, whereas with epithelial cells it’s at the bottom of it

Question 2

What are the 3 major functions of ecm

Answer 2

Strength - Eg cartilage and bone

Communication

Cell migration/ polarity

Question 3

What 3 things are in ecm which allow communication/signalling

Answer 3

Gf
Hormones
Cytokines

Question 4

Cell migration occurs when cells pull on the matrix. What is this important for

Answer 4

Embryonic development
Angiogenesis
Tumour development - metastasis
Wound repair

Question 5

What makes the ecm basal lamina

Answer 5

Cells surrounding it

Question 6

Is the basal lamina conserved

Answer 6

Yes. Seen in most organisms so similar epithelial tissue

Question 7

What 2 type 1 collagens are in basal lamina

Answer 7

IV and XVIII (4 and 18)

Question 8

Other than collagen IV and XViII what is in basal lamina ecm

Answer 8

Fibronectin and laminin

Question 9

What are the cells called in connective tissues which are always there

Answer 9

Indigenous

Question 10

What 3 types of cell are in connective tissue (with lots of ecm)

Answer 10

Primitive mesenchymal cells

Fibroblasts

Specialised cells

Question 11

What are primitive mesenchymal cells

Answer 11

Undifferentiated in the connective tissues. They differentiate into specialised eg chondrocytes,mast cells, adipocytes

Question 12

What do fibroblast cells do in connective tissue

Answer 12

Produce a lot of ecm in connective tissues

Question 13

What type of specialised cells make matrix forming Cartilage

Answer 13

Chondrocytes

Question 14

What type of specialised cells make ecm forming bone

Answer 14

Osteoblasts

Question 15

Why is matrix needed eg for bone via osteoblast matrix production

Answer 15

For flexibility of bone

Question 16

What other than indigenous cells are there

Answer 16

Immigrant cells eg lymphocytes finding ag in connective tissue

Question 17

What 3 types of protein is present in ecm connective tissues

Answer 17

GAGs/ proteoglycans

Fibrous proteins (collagen)

Other glycoproteins (fibronectin,elastin)

Question 18

What happens to the 3 protein types in structure like bone nd teeth and cornea

Answer 18

They get calcified for strength

Question 19

What gives gags an anionic charge -ve

Answer 19

Sulphated

Question 20

What repeating disaccharide makes up gags

Answer 20

N acetyl glucosamine and glucuronic acid

Sulphated

Question 21

Give examples of gags

Answer 21

Heparin sulphate
Chondroitin sulphate
Keratin sulphate
Hyaluronan / hyaluronic acid

Question 22

What do gags link to to form proteoglycans

Answer 22

Core proteins (serine links tetrasachride then the gag)

Question 23

Give example of a simple proteoglycans (1 gag and 1 core)

Answer 23

Decorin

Question 24

What are complex proteoglycans

Answer 24

Where many gags join into a single core protein

Question 25

Give example of a complex proteoglycan

Answer 25

Aggrecan

Question 26

What does aggregation of aggrecans form on 1 linked protein called

Answer 26

Hyaluron (the linker protein)

Question 27

What does -ve charge allow for function of gags

Answer 27

Binding of many h20 molecules

Question 28

What does aggrecan becoming an auto antigen for B cells cause disease wise

Answer 28

Rheumatoid arthritis

Question 29

Which cells make collagen/fibrous proteins in ecm

Answer 29

Fibroblasts

Question 30

Explain the structure of collagen

Answer 30

3 a polypeptides form a triple helixes inside cell Then transported out where they aggregate forming fibrils Then fibrils aggregate to form a collagen fibre

Question 31

Is collagen the most abundant protein in ecm

Answer 31

Yes

Question 32

How many diff genes are for collagen

Answer 32

40

Question 33

Type 1 included XVIII (in connective tissues and basal lamina), what is type 2 and where is it

Answer 33

Type 2 is found in cartilage Can be collagen II or IX

Question 34

What substance prevents aggregation of diff helixes to form a fibril inside cells

Answer 34

Procollagen (cleaved by enzymes outside of cell to form fibres)

Question 35

What do fibronectin glycoproteins do

Answer 35

They allow the ecm Eg collagen to indirectly connect to integrons and the cytoskeleton of a cell Forms cell ecm connection

Question 36

What is elastin in ecm for

Answer 36

For stretch eg of arteries

Question 37

What cell receptors do cells express to allow them to bind to ecm via extracellular domain

Answer 37

Integrins (a and b)

Question 38

What things do integrins bind to in ecm eg in basal lamina

Answer 38

Collagen IV or XVIII

Question 39

Which integrin subtype needs fibronectin to bind to ecm

Answer 39

A5b1

Question 40

How many integrins are there

Answer 40

24

Question 41

Which adaptor protein is used by integrin for it to make contact with actin/vinculin

Answer 41

Talin (integrin associated protein)

Question 42

Which cellular pathway is activated via integrin ecm and cell binding via talin and collagen

Answer 42

FAK Focal adhesion kinase (for migration, gene expression)

Question 43

Why does integrin need to be activated and then inactivated

Answer 43

For movement of cells along the matrix | When activated it has stronger talin and ecm binding