L8. ECM

Question 1

What is the function of the ECM?

Answer 1

provide structural support for cells to organize into tissues
all tissues need ECM to assemble

Question 2

What is the ECM

Answer 2

1. composed of proteins and polysaccharides

2. substance secreted by cells into their outside environment

Question 3

What does the ECM do?

Answer 3

1. gives structural support
2. regulates growth and development of cell
3. regulates migration of the cell
4. signals that regulate cell survival
5. forms adhesive contacts with the cell
6. modifies cell shape and function
7. directs proliferative activity

Question 4

What are the 2 types of ECM?

Answer 4

1. Basement Membrane

2. Connective tissue

Question 5

What is the connective tissue composed of?

Answer 5

1. fibers

2. ground substance

Question 6

What is the function of ground substance in connective tissue?

Answer 6

1. resist compression

2. permits diffusion of nutrients and waste between cells

Question 7

What is the function of fibers in connective tissue?

Answer 7

provide structural support

Question 8

What are the 2 proteins that make fibers

Answer 8

collagen +elastin

Question 9

what is ground substance

Answer 9

kelly like

made up of water,electrolyte , polysaccharide and proteins

Question 10

How many collagen genes are there in humans

Answer 10

29

Question 11

Describe collagen

Answer 11

1. flexible,strong resistant to stretching
2. main protein in the ECM
3. major body protein
4. made of 3 intertwining fibers: tropocollagen ( alpha helical)

Question 12

Name 2 GAGs

Answer 12

1. heparin

2. hyaluronic acid

Question 13

What is hyaluronic acid?

Answer 13

1. huge and abundant GAG
2. only GAG that indirectly binds to proteins
3. good lubricant found in joints
4. involved in wound repair, cell migration, inflammation

Question 14

What causes MPS (mucopolysaccharidoses)

Answer 14

inability to break down GAGs

Question 15

What is fibronectin?

Answer 15

a GP; needed for blood clottting

Question 16

what is aggracan

Answer 16

PG ; found in cartilage

Question 17

draw how hyaluronic acid binds to collagen

Answer 17

associates with link proteins ( L8, pg 11b)

Question 18

what do fibroblasts secrete

Answer 18

they secrete precursors for BOTH collagen and the ECM.

Question 19

What is the basement membrane

Answer 19

interface between the epithelial cells and the connective tissue

Question 20

What are the 2 distinct parts of the basement membrane

Answer 20

1. basal lamina ( made by epithelial cells)

2. reticular lamina (made by CT)

Question 21

What are the 2 layers of the basal lamina ?

Answer 21

1. lamina lucida

2. lamina densa

Question 22

What is the lamina lucida, what does it contain

Answer 22

(part of the basal lamina of the basement membrane)

GP laminin and GP integrins

Question 23

What is integrin

Answer 23

A Glycoprotein

Question 24

Name some PG

Answer 24

aggracan, perlecan

Paul Gifted A Pelican

Question 25

Name some GP

Answer 25

fibronectin,laminin, integrins

God Paul Licked Fido’s Intestines

Question 26

What is the lamina densa, consists of?

Answer 26

(part of the basal lamina of the basement membrane)
collagen 4
PG perlecan
GAG heparan

Question 27

What is the functin of laminins

Answer 27

A GP that binds collagen and integrins - bridge between both layers

Question 28

What does the reticular lamina contain?

Answer 28

collagen 1 and 3
anchoring fibrils
GP fibrillin

Question 29

Draw the relation between the BM, epithelial cells and CT ( add the basal lamina ( lamina lucida and lamina reticular) and the reticular lamina)

Answer 29

pg 14a

Question 30

What are the functions of the BM?

Answer 30

1. provide structural support
2. anchor the epithelium ( firm +flexible)
3. molecular filter for the epithelium

Question 31

What is alport syndrome?

Answer 31

lost of collagen 4

Question 32

How is the ECM attached to cells

Answer 32

junctional anchoring transmembrane protein

link to cytsokeleton via cytoskeletal linkers with adhesion complex

Question 33

What are the 2 types of integrin, how many of each

Answer 33

the 2 PG : alpha (18) and beta (8)

Question 34

What composes a functional integrin

Answer 34

an alpha and beta integrin

Question 35

What determines the function of the integrin heterodimer

Answer 35

the individual alpha beta subunits that compose the dimer

Question 36

Draw the integrin adhesion complex

Answer 36

(pg 17a)

Question 37

describe focal contacts, which cytoskeleton do they link to

Answer 37

link to actin filaments
made up of integrins
composed of a variety of integrin heterodimers

Question 38

Describe hemidesmosomes, which cytoskeleton do they link to

Answer 38

feature of epithelial cells
binds to lamina lucidia
link to intermediate filament
made up of a6b4 integrin

Question 39

What are the 2 modes of integrin activation?

Answer 39

1. intracellular: integrin bind proteins inside the cell and convert it to high affinity
2. extracellular: integrin bind to ECM proteins converts it from low affinity to high affinity

Question 40

What are the 4 functions of integrin?

Answer 40

1. cell migration
   - would healing
   - neuron path finding
   - immune function
2. cell signalling
3. cytoskeletal organization (because of link to junctional proteins)
4. stable adhesion
   - muscle tendon attachemnt
   - attachment to diff skin layers

Question 41

What causes junctional epidermolysis bullosa?

Answer 41

loss of integrin

Question 42

What is collagen 4 in the BM used for

Answer 42

• part of the lamina densa ( and part of reticular lamina)

Question 43

What collagen makes anchoring fibrils

Answer 43

collagen 7