Vascular Cell Biology Flashcards
WHat is the mission of the cardiovascular system? Where does this occur?
maintain the quality and volume of ECF.
this occurs in the microvascular capillary bed (where the action happens).
to survive a cell must be less than 200 um from a capillary
Describe the flow of blood throughout the vasculr system
heart
elastic arterries
muscular arteries
small arteries (arterioles)
***CAPILLARY BED ***
post-caillary venules
venules
medium veins
large veins
heart
WHat are the 3 tunicas of BV walls
- Tunica Adventitia (outer)
- CT (connective tissue)
- Tunica Media: the most variable
- SMCs and CT (changes as you go from large to smaller vessels in the vascular system)
- Tunica intima (inner)
- an endothelium of endothelial cells (ECs)
- simple squamous eith basal lamina
- continous: except in capillary beds where they’re continous or disctontinous depending on what organ you are in
- 1% of ECs turn over everyday
- an endothelium of endothelial cells (ECs)
What is the significane of the Tunica intima?
it is an endothelium!
it is continous except for int eh capillary bed where is can be continous or discontinous
and 1% of the endothelial cells turn over every day. very active!
describe the 3 “tunics” of the heart
endocarium: simple squamous endothelium/basal lamina
myocardium: myocytes and firboblasts, attached to a dense CT skeleton
epicardium: simple squamous, niche for adult resident cardiac stem cells
What is the role of the epicardium during development?
- during development, epicardial cells grow over the surface of the heart as a thin, mono-cellular covering
- these epicardial cells give rise to:
- cardiac fibroblasts
- coronary arteries
- endothelial cells
- SMCs
- cardiac myocytes
What are the large vessels in the body?
Large elastic arteries
large veins
what are the 3 layers of the large elastic arteries? what is theri function? what is a clinical correlation?
they have a thick wall!!
- Adventitia: external elastic membrane
- Media: thickest
- circular SMCs with 40-70 elastic lamellae (these lamellae are a major morphological characteristic)
- lamellae inceases with age, hypertension
- Intima ECs:
- continous: tight junctions and pinocytotic vesicles
Function: elastic recoil to maintain BP during diastole
Clinical: Aneurysms occur in large arteries
What are the walls of veins like?
thin wall!
the adventitia is the tickest tunic in large veins (remember the media was the thickest in arteries)
What are the medium vessels?
medium (muscular) arteries
Medium veins
what are the 3 layers of the medium muscluar arteries? what is the function? what is a clinical correlation?
- Adventitia
- Media: prominent; 40 layers of SMCs, less elastin but still some!
- Intima: internal elastic lamina
Function: SMCs regulate BP
Atherosclerosis
What is atherosclerosis?
intimal plaques (in the tunica intima) caused by ‘foam cells’
- Macrophages ingest LDL (bad cholesterol)
- SMCs migrate to the intima and ingest LDL
this leads to foam cells. they looked washed out like foam bc they have cholesterol/fat in them
Plaques calcify, platelets attach, this leads to thrombosus which leads to MI/stroke
What are teh medium veins like?
like large veins but smaller
what is a differnece histologiclly betwen the medium artery and vein?
veins don’t have an internal elastic lamina in the tunica intima, but arteries do
What are the small vessels, where are they located? what are the layers? what is the function? what is a clinical correlate?
Small arteries and arterioles!
T. media: 8layers in the small artery, declining to 2 layers in the SMC arterioles
Function: SMCs regulate bloodflow to the capillary bed
Clinical: lipid uptake by SMCs narrows the lumen leading to hyertension
What is the diamter of the lumen of a capllary like? what kind of tissues are capillaries made of?
diameter of lumen accepts 1 RBC
1 endothelial cell can make up this tube (note that endothelium is only used when talking about capillaries). it is made of simple squamous endothelium with a basal lamina.
It does not have a media or adventitia
WHat are the 3 types of capillaries?
Type I: continuous
Type II: fenestrated
Type III: Sinusoidal
What is a Type I continuous capillary like?
- tight junctions that only pass proteins < 10kDa
- pinocyttic vesicles: pass proteins>10kDa
- pinocytotic vesicles aren’t present in CNS (BBB)
- continuous means no space between the cells bc there are tight junctions
Wat are type II fenestrated capillries like?
100nm ‘windows’=permanet pinocytotic vesicles
pass proteins>10kDa
WHat are type III sinusoidal capillaries like?
they have discontinuities between adjacent ECs
largers than type I and II about 30um in diameter
what type of capillary is this?
Type I (continous) capillary
10um diameter
this tight junction is uniting parts of the same cell
What type of capillary is this?
Type II (fenestrated Capillary)
10 um diameter
‘permanent’ pinocytotic vesicles that pass proteins>10kDa
what type of capillary is this?
Type III Capillary
30 um diameter
sinusoidal
discontinous
Where do we find continous capillaries and what item are they transporting?
CNS (BBB)
Heart
Skeletal Muscle
Lung
**item transported=oxygen
Where do we find fenestrated capillaries and what item are they transporting?
endocrine glands
GI tracts
kidneys
transporting hormones, nutrients ions
(there is a lot of secretion in these organs)
Where do we find sinusoidal capillaries and what item are they transporting?
bone marrow
spleen
liver
transporting whole cells
What are the functions of Endothelial cells?
- exchange of gases and nutrients
- gases: through cell membrane
- nutrients: through pinocytotic vesicles, fenestrations, and discontinuities
- secrete regulatory molecules
- vasoactive factors
- endothelin: vasoconstrictor
- NO (nitric oxide) vasorelaxant
- Growth factors: (activate angiogenesis)
- FGF: fibroblast growth factor
- PDGF: platelet-derived growth factor
- VEGF: vascular enothelial growth factor
- vasoactive factors
what are the steps involved in angiogenesis?
- Activation of EC receptors
- outgrowth, migration, etc.
- Inhibition of angiogenic growth
What is angiogenesis? and what are some activators and inhibitors?
Angiogenesis: new vessels from existing BVs (adult)
Vasculogenesis denoted embryonic BV development
- Activators: ECs are the target
- ligands: VEGF, FGFs, angiopoietin-1 (vasoactive facotr that induces angiogenesis)
- Receptors: VEGFR, FGFR, TIE-2 (the receptor for angiopoietin-1)
what are some clinical therapies relating to angiogenesis?
- Pro-Angiogenic: for ischmeia in heart and extremities
- BV growth induced by VEGF and FGF
- Anti-Angiogenic: combat tumors
- 1 EC can suport 50 tumor cells
- ANgiostatin and endostatin inhibit new BV growth
WHat are 3 examples of current clinical trials involving angiogenesis?
- Proangiogenic therapy for lower limb ischemis using VEGF cDNA
- endoviral vector, so levels of VEGF increase and lead to increased vascularization. salvages ischemic limbs (don’t give to cancer patient)
- Anti-Angiogenic vis Endostatin
- worked in mice to kill tumors but not yet in humans
- Bevacizumab: Avastatin
- anti-VEGF monoclonal antibody
