Vascular Endothelium Flashcards
What is the structure of blood vessels?
What is found in each structural layer?
Tunica adventitia-vasa vasorum and nerves
Tunica media- smooth muscle cells
Tunica intima- endothelium
Where does nutrient and oxygen and exchange happen?
What structural aspects does it make it ideal for exchange?
Capillaries in the endothelium
Shared between arterial and venous blood
Flat, 1 cell thick, low proliferative rate (long lived)
What are angiocrine factors?
Factors produced by endothelial cells that allow tissue homeostasis-and therefore tissue specific endothelium to be formed
They are tissue specific
Eg for hepatocytes
How are new blood vessels formed?
What drives it?
Why angiogenesis useful in the body?
Sprouting angiogenesis
Driven by hypoxia = makes angiogenic growth factors
These bind to capillary endothelium binding = activation
EC (endothelial cell) proliferates and migrates
ECM remodelling
Tube formation
Loop formation
Vascular stabilization
Utility= menstruation, wound healing, foetal development
What is the relationship between cancer and angiogenic factors?
What is this switch known as?
As cancer grows, it requires its own blood supply, so it binds to a blood vessel and stimulates angiogenic factors. This allows it to have its own supply, this is known as the angiogenic switch
What is the difference between leukocyte recruitment in post capillary venules and arteries atherosclerosis?
PVC: 1 cell thick so they do not get stuck and can transmigrate into tissue
Arteries: have tunica intima and media, so leukocytes get stuck in the subendothelial space, monocytes also migrate here and turn into macrophages = foam cells = atherosclerosis
How does an activated endothelium affect vascular permeability and therefore affect atherosclerosis?
When the endothelium is activated the increased permeability and leakage of plasma proteins allows LDL and OxLDL to enter the subendothelial space and get stuck there = further activation of endothelium = foam cells
What is shear stress and how does it affect atherosclerosis?
Atherosclerosis happens more at bifurcation and curvatures of arteries
This is because the pattern of blood flow has an effect on the development of atherosclerosis, in branches and curvatures the blood flow is disturbed and there is a low wall shear
Laminar blood flow(high shear stress): anti-thrombotic, anti-inflammatory, LIKED
Disturbed: thrombosis stimulated, inflammation stimulated, less nitric oxide formed = more likely to form atherosclerosis
What are the contradicting good and bad effects of angiogenesis?
Bad= Promotes plaque growth at vasa vasorum in tunica adventitia
Good = prevents damage post-ischaemia
What are the 6 functions of the endothelium?
VIPATH
Vascular tone
Inflammation
Permeability
Angiogenesis
Tissue homeostasis
Haemostasis
What is endothelial cell plasticity?
The ability of endothelium to be able to differentiate
What are the 4 mechanisms of endothelial dysfunction in atherosclerosis?
Leukocyte recruitment - due to inflammation
Permeability
Shear stress
Angiogenesis
