Vascular Biology II

Question 1

What type of junctions are found in continuous capillaries?

Answer 1

Tight junctions between endothelial cells. One cells folds over the other cell “marginal folds”

Question 2

Do endothelial cells have pores of fenestrae?

Answer 2

NO

endothelial cells lack pores or fenestrae

Question 3

How is information transferred in endothelial cells within continuous capillaries?

Answer 3

numerous pinocytotic vessicles

Question 4

Where are continuous capillaries located? (4)

Answer 4

1) Brain
2) Muscle
3) Connective Tissue
4) Exocrine Glands

Question 5

Where are fenestrated capillaries located?

Answer 5

Where rapid exchange of substances between the blood and tissue occurs

1) Kidney, nonglomerular
2) Endocrine glands
3) Intestines
4) Kidney [glomerulus- diaphrafms absent]

Question 6

Describe the fenestrae (pores) present in the endothelial walls of fenestrated capillaries?

Answer 6

Pores are usually closed by a thin diaphragm

the basal lamina is continuous

Question 7

How does the diameter of fenestrated capillaries compare to continuous capillaries?

Answer 7

They have the same diameter (5-10 micrometers)

Question 8

Which type of capillary has a large opening between the endothelial cells?

Answer 8

Sinusoidal

Question 9

Describe the basal lamina of the three different types of capillaries.

Answer 9

Continuous: well-developed
Fenestrated: continuous
Sinusoidal: DISCONTINUOUS OR ABSENT

Question 10

What capillary type is associated with macrophages?

Answer 10

sinusoidal

Question 11

Which type of capillary has the largest diameter?

Answer 11

sinusoidal (30-40 micrometers)

Question 12

Where are sinusoidal capillaries located?

Answer 12

In areas of rapid exchange and where cells can be exchanged

1) Red bone marrow
2) Liver
3) Spleen
4) Adrenal cortex

Question 13

What are the smallest types of veins?

Answer 13

Pericytic and muscular venules

Pericytic are smaller of the two

Question 14

Veins have valves which can be used to indicate blood flow direction.

Answer 14

Look at the picture and know this.

Question 15

What is the key identifier of large veins?

Answer 15

Longitudinal bundles of smooth muscle in the adventitia

*longitudinal arrangement allows contraction that pushes the blood back to the heart

Question 16

Define vasculogenesis.

Answer 16

De novo vessel formation

Question 17

Define angiogenesis.

Answer 17

Growth from existing EC-derived channels.

Question 18

Define arteriogenesis.

Answer 18

Formation of arteries, arterioles, and collateral vessel remodeling

Question 19

Define neovascularization.

Answer 19

Overarching term to include vasculogenesis, angiogenesis, and arteriogenesis.

Question 20

Define remodeling.

Answer 20

Vascular response to alterations in the environment.

Question 21

What are the two mechanisms of blood vessel formation in the adult?

Answer 21

1) From endothelial percursor cells (EPCs)

2) From pre-existing vessels

Question 22

Which blood vessel formation method do tumors use?

Answer 22

BOTH

tumor angiogenesis employs both mechanism

Question 23

What are EPCs?

Answer 23

angioblast-like cells that reside in the red bone marrow of adults and non-bone marrow niches

Question 24

Describe EPC blood vessel formation. (What 3 things can they do?)

Answer 24

EPCs mobilize from niche and migrate to blood vessel formation site where they

1) Replace lost endothelial cells
2) Re-endothelize vascular implants
3) Neovascularize ischemic organs, wounds, or tumors

Question 25

List the 6 basic steps to blood vessel formation from pre-existing blood vessels.

Answer 25

1) Vasodilation (NO) and increased permeability (VEGF) 2) Degradation of BL mediated by MMPs and disruption of intracellular junctions mediated by plasminogen activator. 3) ANG-2 destabilizes vessels. 4) Migration and proliferation of endothelial cells mediated by VEGF and FGF. 5) Formation of endothelial capillary tube. 6) Elaboration of BL by TGF-B and recruitment of periendothelial cells (pericytes of SMCs) mediated by ANG-1-TIE-2 and PGDF.

Question 26

What is the difference between ANG 2 and ANG 1?

Answer 26

ANG-2 destabilizes ANG-1-TIE-2 stabilizes

Question 27

What is the function of NO?

Answer 27

Vasodilation of pre-existing blood vessel

Question 28

What is the function of VEGF?

Answer 28

1) increased vascular permeability of pre-existing vessel | 2) induces migration and proliferation of endothelial cells

Question 29

What is the purpose of MMPs?

Answer 29

Proteolytic degradation of the basal lamina of the parent vessel by metalloproteinases

Question 30

What mediates the loss of cell-to-cell contact?

Answer 30

Plasminogen activator

Question 31

What three factors mediate the endothelial cell migration and proliferation?

Answer 31

VEGF angiopoietin 2 Fibroblasst growth factor 2

Question 32

What periendothelial cells are recruited in blood vessel formation?

Answer 32

1) Pericytes for capillaries | 2) Pericytic venules and smooth muscle cells for larger vessels

Question 33

What factor is responsible for elaboration of basal lamina elements?

Answer 33

TGF-beta transforming growth factor

Question 34

What mediates the recruitment of periendothelial cells?

Answer 34

Interaction of Ang 1 with the Tie2 receptor on endothelial cells

Question 35

What is the function of PDGR (platelet derived growth factor)?

Answer 35

Induces recruitment of smooth muscle cells

Question 36

How is Ang 2 involved in the remodeling process?

Answer 36

by blocking the stabilizing function of Ang 1

Question 37

What are 6 potential clinical benefits of proangiogenesis ?

Answer 37

``` MI (myocardial ischemia) Peripheral ischemia Cerebral ischemia Wound healing and fracture repair Reconstructive surgery Transplantation of islets of Langerhans ```

Question 38

What are 6 potential clinical benefits of antiangiogenesis?

Answer 38

``` Tumor growth and metastases Ocular neovascularization Hemangiomas Rheumatoid arthritis Atherosclerotic plaque neovascularization Birth control ```

Question 39

How can endothelial cells of tumor vessels be specifically targeted?

Answer 39

They express a prtn called tumor endothelial marker 8 (TEM8) Since this prtn is preferentially expressed in tumor vessels, the marker ca be used to specifically deliver drug molecules to tumor vessels

Question 40

Why can the great saphenous vein be used in coronary bypass surgery?

Answer 40

Atypical vein: 2 or 3 layers of smooth muscle in its media Wall remodeling will occur after the bypass to make it even more suitable!