Vascular endothelium

Question 1

Describe the 3 layers of all blood vessels (except capillaries and venules).

Answer 1

3 layers:
- Tunica adventitia
- Tunica media
- Tunica intima

Question 2

Where does Non fenestrated vascular endothelium exist?

Answer 2

muscle, lungs, skin, BBB

Question 3

Where does fenestrated endothelium exist?

Answer 3

kidney glomerulus, GI tract

Question 4

Where does discontinuous endothelium exist?

Answer 4

In the liver and marrow sinus

Question 5

What is it called when 2 cells come together to form a junction and stop each other from growing

Answer 5

Contact inhibition

Question 6

What does contact inhibition allow the formation of?

Answer 6

A flat monolayer

Question 7

What pathways are on when the endothelium is resting? (3)

Answer 7

• Anti-inflammatory
• Anti-thrombotic
• Anti-proliferative

Question 8

What pathways are switched on when the endothelium is activated? (3)

Answer 8

• Pro-inflammatory
• Pro-thrombotic
• Pro-angiogenic

Question 9

• What factors can trigger chronic activation of endothelium? (7)

Answer 9

• Viruses
• Smoking
• Mechanical stress
• Inflammation
• OxLDL
• High bp
• High glucose

Question 10

What does chronic endothelium activation cause? (4)

Answer 10

• Thrombosis
• Senescence- ageing of endothelial cells
• Leukocyte recruitment
• Permeability

Question 11

What is a leukocyte?

Answer 11

White blood cell

Question 12

After the endothelium is injured and activated, describe the steps leading to a lesion of atherosclerosis.

Answer 12

-Injury increases endothelial permeability
-Allows leukocyte infiltration, accumulating in the subendothelial space
-They then phagocytose lipids to create foam cells….

Question 13

What causes leukocyte recruitment.

Answer 13

Inflammatory agents activating the endothelium .

Question 14

Where does leukocyte recruitment usually occur?

Answer 14

In the post capillary venules during inflammation.

Question 15

Where does leukocyte recruitment occur in atherosclerosis?

Answer 15

-Leukocytes adhere to activated endothelium of LARGE ARTERIES and get stuck in the subendothelial space

-Monocytes migrate into sub endothelial space, differentiate into macrophages and become foam cells.

Question 16

At what parts of the vascular system are atherosclerotic plaques more likely to occur?

Answer 16

Bifurcations and curvatures of the vascular tree

Question 17

Which blood vessels in particular is plaques likely to form?

Answer 17

• Aortic bifurcation (at the arch)
• Coronary artery bifurcation
• Carotid artery bifurcation
• Iliac arteries
• Femoral arteries
• In abdomen

Question 18

How does blood flow differ between straight parts and in branches/curvatures of the vasculature?

Answer 18

-In straight parts of the arterial tree, blood flow is LAMINAR and wall shear stress is high and directional.

-In branches and curvatures, blood flow is disturbed with nonuniform and irregular distribution of low wall shear stress

Question 19

What is the effect of laminar blood flow on the endothelium? (4)

Answer 19

• Anti-thrombotic (e.g. thrombomodulin) and anti-inflammatory factors
• Endothelial survival
• Inhibition of SMC (vascular smooth cell) proliferation
• Nitric oxide production

Question 20

What is the effect of disturbed blood flow on the endothelium? (4)

Answer 20

• Promotes thrombosis and inflammation (leukocyte adhesion)
• Endothelial apoptosis
• SMC proliferation
• Loss of NO production

Question 21

What is the importance of NO in the cardiovascular system? (6)

Answer 21

It’s essential for the health of the system:

• Reduces oxidation of LDL cholesterol (major component in plaque)
• Dilates blood vessels
• Reduces platelet activation
• Reduces release of superoxide radicals
• Reduces proliferation of SMC in the vessel wall
• Inhibits monocyte adhesion