Vascular Endothelium Flashcards
Describe the extent of the vascular system
one of the largest and the most extensive networks in the body
What percentage of endothelial cells are in the microvascular system?
98%
What is the basic structure of blood vessels?
Tunica adventitia
Tunica media
Tunica intimia
What are vasa vasorum?
Tiny vessels that feed larger vessels
What is the structure of capillaries and venules?
only by endothelium, supported by some mural cells (pericytes) and a basement membrane
What happens in capillaries?
exchanges of nutrients and oxygen between blood and tissues occur
What is the function of the microvascuar endothelium?
promotes tissue homeostasis
How does the microvascular endothelium promote tissue homeostasis?
Microvascular endothelium is the source of angiocrine factors required for the maintenance of tissue homeostasis and organ regeneration
Dysfunctional endothelium contributes to disease more than any other “organ”: give examples of some diseases
Ischemia
Chronic inflammatory diseases
Cancer
Diabetes
How is the microvascular endothelium different between systems?
Endothelial cells and microvasculature have organotypic (tissue-specific) properties and expression profiles
What is the basic concept of the endothelial cells?
Flat
Large surface area
From one cell deep monolayer
Acts as a vital barrier separating blood from tissues
What is contact inhibition?
Process that takes place when the junction between to cells come together
The establishment of the junction signals the cell to stop growing
What is the lifespan of endothelial cells?
In vivo, endothelial cells live a long life and have a low proliferation rate (unless new vessels are required: angiogenesis)
What are the multiple functions of blood vessels?
Tissue homeostasis and regeneration Vascular tone Angiogenesis Permeability Inflammation Haemostasis & Thrombosis
All controlled by endothelium
What are the products of endothelial cells that regulate thrombosis and haemostasis?
Antithrombic factors
Procoagulant factors
What pathways are activated when a trigger is present?
Pro-inflammatory
Pro-thrombic
Pro-angiogenic
What triggers can activate endothelium?
Smoking Viruses Mechanical stress Inflammation High blood pressure OxLDL High glucose
How can the endothelium respond to triggers?
Thrombosis
Senescence
Permeability
Leukocyte recruitment
What are the products of endothelial cells that regulate angiogenesis?
Matrix Products
Growth factors
What are the products of endothelial cells that regulate inflammation?
Adhesion molecules
Inflammatory mediators
What are the products of endothelial cells that regulate vascular tone permeability?
Vasodilator factors
Vasoconstricting factors
What is the pathogenesis of atherosclerosis?
Endothelial dysfunction - activation causes increase in permeability and upregulation of the systems that promote the adhesion of leukocytes
Leukocytes migrate and accumulate in the sub-endothelial space
Phagocytosis of the lipids in the sub-endothelial space leads to
Fatty-streak formation
Formation of necrotic core
Angiogenesis
What stimuli cause atherosclerosis?
Hypercholesterolaemia Diabetes Mellitus Hypertension Sex hormonal imbalance Ageing Oxidative stress Proinflammatory cytokines Infectious agents Environmental toxins Hemodynamic factors
What are the 4 mechanisms that contribute to the formation of atherosclerotic plaques?
Leukocyte recruitment
Permeability
Shear stress
Angiogenesis