Extracellular Matrix

Question 1

ECM

Answer 1

complex network of proteins and polysaccharides that are secreted locally by cells and remain closely associated to provide structural, adhesive and biochemical support

Question 2

location of ECM

Answer 2

basement membrane, bone, tendon, subcutaneous fat etc (vary in ratio of components)

Question 3

ECM contains (acellular)

Answer 3

-fibres: collagen and elastin
-ground substance: proteoglycans, glycosaminoglycans and glycoproteins

Question 4

funtion of ECM

Answer 4

-mechanical and structure support
-tensile strength
-anchors cell (cell-ECM junction)
-influence embryonic development
-pathway for cell migration

Question 5

ECM macromolecules

Answer 5

collagen, elastin, proteoglycans, hyaluronan (GAG) and glycoproteins

Question 6

skin and blood vessels

Answer 6

high ratio of elastin
-resilience

Question 7

cartilage

Answer 7

high ratio of collagen
-tensile strength

Question 8

bone

Answer 8

calcified collagen
-incompressible

Question 9

fibroblasts produce

Answer 9

collagen

Question 10

collagen secretion

Answer 10

out in the ECM by exocytosis

Question 11

collagen I

Answer 11

dermis, tendons, ligaments and bones

Question 12

collagen II

Answer 12

hyaline cartilage

Question 13

collagen III

Answer 13

liver, bone marrow, lymphoid organs: also in granulation tissue aka reticulin

Question 14

collagen IV

Answer 14

basement membranes

Question 15

collagen V

Answer 15

linker to basement membrane

Question 16

elastin

Answer 16

structural protein arranged in fibres and surrounded by glycoprotein fibrillin
- form fibrous network within connective tissue

Question 17

ground substance

Answer 17

amorphus, colourless and fills space between fibres and cells
- provides medium for exchange of substances
- consists of GAGs which form proteoglycans

Question 18

GAGs function

Answer 18

trap water which makes them jelly like
- resistance to compressive force

Question 19

ECM water content

Answer 19

90%

Question 20

aggrecan

Answer 20

proteoglycan found in cartilage
GAG: chondroitin sulphate and keratan sulphate

Question 21

perlecan

Answer 21

proteoglycan located in basement membrane
GAG: heparan sulphate

Question 22

syndecan

Answer 22

proteoglycan located in cartilage
GAG: chondroitin sulphate and heparan sulphate

Question 23

decorin

Answer 23

located in connective tissue
GAG: chondroitin sulphate and dermatan sulphate

Question 24

hyaluronan (GAG)

Answer 24

synovial fluid
-hyaluronic acid

Question 25

chondroitin sulphate (GAG)

Answer 25

cartilage

Question 26

keratan sulphate (GAG)

Answer 26

cartilage

Question 27

heparan sulphate (GAG)

Answer 27

basement membrane

Question 28

hyaluronic acid

Answer 28

viscous and binds cells together - lubricates joints

Question 29

hyaluronidase enzyme

Answer 29

produced by WBCs and sperm - breaks down hyaluronic acid - aids spread and movement

Question 30

glycoprotein fibrillin

Answer 30

controls deposition and orientation of elastin

Question 31

glycoprotein fibronectin

Answer 31

linker role in basement membrane; organises ECM and attaches cell to BM

Question 32

glycoprotein laminin

Answer 32

primary organiser of basement membrane layer

Question 33

glycoprotein entactin

Answer 33

linker role in BM

Question 34

tenascin

Answer 34

linker role in connective tissue

Question 35

proteoglycan synthesis

Answer 35

in the rER then to golgi where polysaccharides as disaccharide repeats (GAGs) - delivered to ECM by exocytosis