CVR - Vascular endothelium Flashcards
What are the functions of the endothelial cell in blood vessels and tissues?
- Tissue homeostasis and regeneration
- Permeability
- Inflammation
- Haemostasis and thrombosis
- Angiogenesis
- Vascular tone
What does it mean when it is said that the endothelial cells are heterogeneous?
The function and phenotype of depends on their location
In resting endothelium, which pathways are activated?
All of the anti’s:
- Anti-inflammatory
- Anti-thrombotic
- Anti-proliferative
In activated endothelium, which pathways are activated?
All of the pro’s:
- Pro-inflammatory
- Pro-thrombotic
- Pro-angiogenic
What can occur due to chronic activation of the endothelium?
- Thrombosis
- Senescence: cells age and do not divide, but not dead
- Leukocyte recruitment
- Increased permeability
How does atherosclerosis occur?
- Increased endothelial permeability
- Increased leukocyte migration and adhesion causes leukocytes to go into the sub-endothelial space
- Phagocytosis of the lipids in the sub-endothelial space results in foam cell formation
- This eventually leads to an advanced complicated lesion of atherosclerosis where more and more macrophages accumulate
- This forms a necrotic core
What are the risk factors and stimuli for atherosclerosis?
- Hypercholesterolaemia
- Diabetes mellitus/metabolic syndrome
- Hypertension
- Sex hormone imbalance
- Ageing
- Oxidative stress
- Proinflammatory cytokines
- Infectious agents
- Environmental toxins: e.g. smoking
- Haemodynamic factors
Why does atherosclerotic plaque occur preferentially at bifurcations and curvatures of the vascular tree?
The flow patterns and haemodynamic forces are not uniform in the vascular system
Why is it good to have laminar blood flow on the vascular endothelium?
Laminar flow causes a high and directional wall shear stress:
- This promotes anti-inflammatory and anti-thrombotic factors
- It promotes endothelial survival
- It inhibits smooth muscle cell proliferation (good against atherosclerosis)
- Promotes production of Nitric oxide
All opposite for turbulent flow
Why do we want to have higher levels of nitric oxide in the blood?
- Dilates blood vessels
- Reduced platelet activation
- Reduced oxidation of LDL cholesterol
- Reduced release of superoxide radicals
- Inhibits monocyte adhesion
- Reduces proliferation of SMC in the vessel wall
What occurs that results in angiogeneis?
Hypoxia
What is angiogenesis?
The formation of new vessels by sprouting from existing vessels
How does angiogenisis lead to plaque growth?
In sub endothelial space, when a plaque forms
