CTB7 Flashcards
What is the primary function of the endothelium?
The endothelium regulates vascular tone, barrier function, and inflammation.
How does the endothelium maintain vascular tone?
It releases vasodilators (e.g., nitric oxide) and vasoconstrictors (e.g., endothelin-1).
What is the structure of the vascular intima?
A single-cell endothelial layer forming a non-adhesive, selective barrier.
How do endothelial cells reduce mechanical stress in large vessels?
They elongate and align with blood flow direction to minimise surface forces.
What is the role of nitric oxide in vascular function?
NO is a potent vasodilator that relaxes smooth muscle and inhibits platelet aggregation.
How is NO synthesised in endothelial cells?
NO is produced by endothelial nitric oxide synthase (eNOS) from L-arginine.
What is endothelial dysfunction?
A state where the endothelium loses its ability to regulate vascular tone and barrier integrity.
What is angiogenesis?
The formation of new blood vessels from pre-existing vasculature.
What stimulates angiogenesis?
Growth factors like VEGF (vascular endothelial growth factor) and hypoxia.
How does the media layer of blood vessels differ between arteries and veins?
Arteries have a thicker, more muscular media to withstand higher pressures.
What is the primary function of vascular smooth muscle cells?
To regulate vascular tone through contraction (vasoconstriction) and relaxation (vasodilation).
How is vascular tone controlled?
By endothelial signals (e.g., NO) and autonomic nervous system input.
What is the adventitia layer?
The outermost layer of blood vessels containing fibroblasts, collagen, and elastin.
How does the adventitia contribute to vascular function?
It provides structural support and elasticity to accommodate pressure changes.
What is the role of gap junctions in the endothelium?
Gap junctions enable cell-cell communication and coordinated responses.
What are the functions of endothelial-derived prostacyclin?
It promotes vasodilation and inhibits platelet aggregation.
How do endothelial cells regulate thrombosis?
They balance pro-thrombotic (e.g., von Willebrand factor) and anti-thrombotic (e.g., NO, prostacyclin) factors.
What is the role of endothelial cell junctions?
They maintain barrier integrity and regulate permeability.
How do inflammatory responses affect the endothelium?
Inflammation increases permeability and promotes leukocyte adhesion.
What molecules mediate endothelial inflammation?
Cytokines (e.g., IL-1, TNF-alpha) and adhesion molecules (e.g., ICAM-1, VCAM-1).
What happens to the endothelium in atherosclerosis?
Endothelial dysfunction leads to lipid accumulation, inflammation, and plaque formation.
What is the internal elastic lamina?
A layer of elastin separating the intima from the media in arteries.
How does shear stress influence endothelial function?
Shear stress enhances NO production and maintains endothelial health.
What are the effects of oxidative stress on the endothelium?
Oxidative stress reduces NO availability and promotes inflammation and thrombosis.
What is the significance of endothelial permeability?
It regulates fluid, nutrient, and immune cell exchange between blood and tissues.
What causes increased endothelial permeability during inflammation?
Cytokines disrupt junctional proteins, creating gaps between endothelial cells.
What is the role of VEGF in endothelial cell function?
VEGF promotes proliferation, migration, and survival during angiogenesis.
How do smooth muscle cells contribute to vascular remodelling?
They proliferate and synthesise extracellular matrix in response to injury.
What is vascular compliance?
The ability of blood vessels to stretch and accommodate changes in pressure.
How does compliance differ between arteries and veins?
Veins are more compliant than arteries, acting as blood reservoirs.
What is the role of endothelin-1?
Endothelin-1 is a vasoconstrictor produced by endothelial cells under stress.
What factors induce endothelial cell apoptosis?
Oxidative stress, inflammatory cytokines, and loss of survival signals (e.g., VEGF).
How does hypoxia influence vascular function?
Hypoxia stimulates angiogenesis and alters vascular tone.
What is the role of the glycocalyx in the endothelium?
The glycocalyx protects endothelial cells and regulates permeability and inflammation.
How does NO inhibit platelet aggregation?
NO prevents platelet activation by increasing intracellular cGMP levels.
What happens to endothelial cells during vascular injury?
They express adhesion molecules to recruit leukocytes and initiate repair processes.
What is the role of pericytes in microvasculature?
Pericytes support capillary stability and regulate endothelial cell function.
How do cytokines affect vascular smooth muscle cells?
Cytokines promote proliferation and migration, contributing to vascular remodelling.
What is the function of the basal lamina in blood vessels?
It supports endothelial cells and separates them from the surrounding tissue.
How do prostaglandins influence vascular tone?
Prostaglandins like PGE2 cause vasodilation or vasoconstriction depending on receptor type.
What is the function of endothelial cadherins?
Cadherins maintain intercellular junctions, ensuring endothelial barrier integrity.
How does inflammation promote leukocyte adhesion?
Endothelial cells upregulate selectins and integrin ligands during inflammation.
What is the role of matrix metalloproteinases (MMPs) in angiogenesis?
MMPs degrade the extracellular matrix to allow endothelial cell migration.
How do endothelial cells detect changes in oxygen levels?
Hypoxia-inducible factors (HIFs) regulate endothelial responses to low oxygen.
What are the stages of angiogenesis?
Endothelial activation, migration, proliferation, and vessel maturation.
How do smooth muscle cells regulate vascular tone?
Through contraction (increasing resistance) and relaxation (decreasing resistance).
What is endothelial senescence?
Age-related dysfunction in endothelial cells, reducing vascular health.
How does turbulent blood flow affect the endothelium?
It induces endothelial dysfunction and promotes atherogenesis.
What is the significance of capillary permeability in tissue health?
It allows nutrient and waste exchange but can cause oedema when dysregulated.
How do endothelial cells respond to mechanical stress?
They release NO and prostacyclin to regulate vascular tone and protect against injury.
