Tissue Generation And Repair

Question 0

Niche

Answer 0

A microenvironment in which somatic stem cells

Question 1

Regeneration vs. repair

Answer 1

Regeneration is the replication/replacement of damaged cells

Repair is the process of regeneration with fibrosis to fix damaged organ/tissue

Question 2

Induced pluripotent stem cells

Answer 2

Induced by 4 txn factors: Oct3/4, Sox2, c-myc and Klf4

- homeobox gene product Nanog

Question 3

Replication cycle checkpoints

Answer 3

Regulated by Cyclin dependent Kinases and CDK inhibitors

- hyperplasia accomplished from G0 stem cell population

Question 4

Malignant melanoma

Answer 4

Failure of p16 to inhibit CDK4/cyclin D results in backdown of G1-> S checkpoint. This results in increasing potential for for damaged DNA to replicate.

Question 5

Signals for cell growth: 5

Answer 5

- All of them respond to growth factor stimulation-> phosphorylation of TRK
MAP-K path (RAS-RAF-MKKK)
IP3
PI3-K path
cAMP 
JAK/STAT

Question 6

Collagen basics

Answer 6

Pro-a chain -> hydroxylation (pro, Lys + vitamin C) -> glycosylation -> assembly of procallagen triplets -> reg pep cleavage to -> collagen assembly

Question 7

Marfan

Answer 7

FBR-1 mutation: fibrillin mutant produces bad elastic fibers -> weak tunica media -> aneurysms

Question 8

Cadherins basics

Answer 8

Calcium dependent adhesion molecules

• ZA, desmos
• integrins - Cadherins - catenens - actin

Question 9

Angiogenesis: defined and process (mechanism A)

Answer 9

Formation of new blood vessels after infancy

• NO, VEGF -> vasodilation
• proteolytic of BM
• migration of Endothelial cells
• proliferation of endo cells
• maturation of ECs
• recruitment of pericytes and sm. muscle

Question 10

Angiogenesis: mechanism B

Answer 10

Angioblast like endo precursor cells recruited from bone marrow to site of angiogenesis

Question 11

Tip and stalk cells

Answer 11

• VEGF binds receptors on tip cells and upregulate txn of transmembrane receptor of DII4 which binds notch receptor on stalk cells, this receptor activates genes to down reg response to VEGF

Question 12

TGF-B

Answer 12

Produced by most cell types in granulation tissue
Promotes migration and proliferation of fibroblasts
Increases synthesis of collagen AND fibronectin
Decreases degredation of ECM by metalloproteinases

Question 13

Phase 1: inflammation (two elements)

Answer 13

Clot formation

Chemotaxis

Question 14

Phase II: Proliferation (3 elements)

Answer 14

• Re-epithelialization
• angiogenesis/granulation tissue
• provisional matrix

Question 15

Phase III: maturation (2 elements)

Answer 15

• Collagen matrix

- Wound contraction

Question 16

Wound healing strength

Answer 16

Day 2: type II collagen and fibronectin predominate

Day 10: type II gone, type I predominates. ~ 10% strength

Question 17

Keloid (correct info)

Answer 17

Type I collagen predominates in dermis

- not localized to area of wound

Question 18

Myofibroblasts

Answer 18

Wound contracture