Lec 3

Question 1

What are the 3 pillars of TERM

Answer 1

Cells
Scaffold
Signals

Question 2

What are the 3 main components of the Cell Theory?

Answer 2

• All living organisms are composed of one or more cells
  
  • The cell is the basic unit of structure and organisation in organisms
  • Cells come from pre-existing cells

Question 3

Who developed the cell theory

Answer 3

Schwann and Schleiden

Question 4

What does the skin consist of ?

Answer 4

epithelial and dermal layer

Question 5

How many tissues classes is the body made up of?

Answer 5

5

epithelial
connective
muscular
nerve 
blood

Question 6

How many types of cell adhesion molecules are there?

Answer 6

5

Anchoring
• Adherens - lateral connections, involves actin filaments (microfilaments) . It is widely involved in cell-cell communications.
• Hemi-desmosomes - anchors to basement membrane/basement lamina
• Desmosomes - attaches to intermediate filaments (which involves keratin) so better suited to anchoring laterally and in skin.

Communication
• Tight junctions - occluding, they are the barriers of epithelial cells and stops solute movement
• Gap junctions - basically like holes in the membrane, allows solutes to travel through and allows for active chemical signaling.

Question 7

Where can you find squamous simple epithelial cells

Answer 7

air sacs of lungs. lining the heart, blood vessels and lymphatics

Question 8

Where can you find squamous stratified epithelial cells

Answer 8

lines the esophagus, mouth, vagina and skin

Question 9

Where can you find cuboidal simple epithelial cells

Answer 9

secretory potion of small glands

Question 10

Where can you find cuboidal stratified epithelial cells

Answer 10

sweat glands and salivary

Question 11

Where can you find columnar simple epithelial cells

Answer 11

bronchi and digestive tract

Question 12

Where can you find columnar stratified epithelial cells

Answer 12

male urethra

Question 13

Where can you find pseudostratified epithelial cells

Answer 13

trachea and URT

Question 14

What makes up adheren junctions?

Answer 14

cadherins
most commonly form homophillic bonds with other cadherins

E-cadherins is a classical cadherin found in skin epithelia

Question 15

What type of cell molecules are found in desmosomes?

Answer 15

Desmocollin and desmogleins are nonclassical cadherins

Question 16

What are hemidesmosomes made of?

Answer 16

integrins

a6B4 integrins is CAM (cell adhesion molecule) found in hemidesmosomes

Question 17

What is Palmoplantar Keratoderma PPK

Answer 17

PPK is a dominant negative mutation - a mutation in which the mutated gene adversely affects the wild type gene. This can be by inhibiting the wild type expression or production. So we can treat them by inhibiting the mutated gene.

It causes thickening of the skin.

Question 18

what mutations cause PPK

Answer 18

Mutations in desmoplatin (a non classical cadherin) result in PPK/woolly hair and cardiomyopathy.
Mutations in cytoskeletal proteins such as keratin 9 and keratin 1 (which bind to desmosomes) result in ppk

Question 19

How do mesenchymal cells connect

Answer 19

They adhere to the ECM by several different cell adhesion molecules (CAMs) of which the major class is integrins. 
This architecture allows the cells to sense mechanical cues.

Question 20

What are the 3 most abundant types of ECM?

Answer 20

• Proteoglycans (carbohydrates polymers)
Heparan sulfate and chondroitin sulfate
• Fibrous ECM (collagens and elastins)
Collagen 1 - in the interstitial
Collagen 4 - basal lamina
Collagen 7 - anchoring firbils

• Multiadhesive matrix proteins
Fibronectin (interstitial) 
Laminin (basal lamina)

Question 21

What do we use to make cell cultures?

Answer 21

T25 flasks

Question 22

How to make mesenchymal cell cultures

Answer 22

We also use collagenase to breakdown the ECM to dissociate cells
Once dissociated the cells stick to the bottom of the flask and start producing ECM again

Question 23

how to make epithelial cell cultures

Answer 23

Trypsin is used to cleave proteins and in this case it would cleave the junctions between the cells.
It is important to only leave the epithelial cells in the trypsin for a short amount of time as it can break down the actual cell too.
Before adding the dissociated cells you have to add laminin or collagen 1 to trick the cells into thinking there is a BM.
Instead of adding laminin or collagen we can also add inactivated mesenchymal cells (meaning non-proliferating) but they still function the same way. Mytomyosin-C can stop proliferatio

Question 24

Focal adhesions in cell culture

Answer 24

They allow the epithelial cells to attach to the BM.
Depending on what substrate the mesenchymal cells are grown on it dictates the properties of how the mesenchymal cells differentiate - hence affecting the focal adhesions