16-vascular Endothelium Flashcards
What are the 3 layers of blood vessels
Tunica Intima - ENDOTHELIUM
Tunica Media - Smooth Muscle Cells
Tunica Adventitia - Vasa Vasorum, Nerves
What is CONTACT INHIBITION
When the endothelial cells divide they know that they have to form a
monolayer
What are the essential functions of vascular endothelium
Inflammation
Vascular Tone and Permeability Angiogenesis
Thrombosis and Haemostasis
What are the 3 stages in response to injury
- Endothelial Dysfunction
- Fatty-Streak Formation
- Formation of an Advanced, Complicated Lesion of Atherosclerosis
What happens to endothelium in inflammation
pro-inflammatory, pro-thrombotic, pro-angiogenic factors
How are leukocytes recruited into tissues via the endothelium
selectins on the leukocyte which can weakly interact with the endothelium and make the leukocyte roll
• Inside the leukocyte there are signals which activate the integrins (switching them to the high affinity state)
• The integrins can then strongly bind to the ligands on the endothelium
• The leukocyte then binds, adheres and transmigrates
How is leukocyte recruitment differen tin normal tissue and atherosclerosis
Recruitment of blood leukocytes into tissues takes place normally during inflammation: leukocyte adhere to the endothelium of post-capillary venules and transmigrate into tissues
• In atherosclerosis, leukocytes adhere to activated endothelium of large arteries and get stuck in the subendothelial space
• Newly formed post-capillary venules at the base of developing lesions provide a further portal for leukocyte entry
What do laminar and turbulent flow promote
Laminar blood flow promotes:
Nitric oxide production
Factors that inhibit coagulation, leukocyte adhesion, smooth muscle cell proliferation
Endothelial survival
• Turbulent blood flow promotes:
Coagulation, leukocyte adhesion, smooth muscle cell proliferation
What is angiogenesis
Angiogenesis is the formation of new blood vessels by sprouting from pre- existing vessels
When tissue is hypoxic, it will release
chemicals which activates the existing
blood vessels which triggers a change in the cell
How does angiogenesis contribute to the growth of plaques
When you have an advanced plaque and it gets to a size where there is a lot of
necrotic debris inside and there is hypoxia - the hypoxia stimulates
angiogenesis from the little vessels (vasa vasorum)
• The vasa vasorum vessels are fragile and more leukocytes will come in and
contribute to the growth of the atherosclerotic plaque
What is senescence
Senescence is growth arrest that halts the proliferation of ageing and/or
damaged cells
• This is a clever way of making sure that damaged cells don’t take over and is considered to be a protective mechanism against cancer
• The bad thing about senescence is that senescent cells can develop a PROINFLAMMATORY PHENOTYPE
As senescent cells have a pro-inflammatory
and pro-thrombotic phenotype, they can contribute to atherosclerotic plaque progression
