cell biology of cardiovascular system Flashcards
what are the 3 layers of blood vessels? does the thickness of these three layers vary depending on the blood vessel? if yes what does it depend on?
the intimate, the media, the adventia
yes, it depends on the vessel type and its position in the vascular tree
what is the intima’s role? and what is it composed of?
ensures effective exchange of gases and nutrients between blood and the rest of the body
it is composed of endothelial cells
what is the morphology of endothelial cells of the intima?
these endothelial cells have a cobblestone morphology
what are the main functions of the endothelium?
regulation of vascular tone, barrier function, inflammatory responses, thrombosis, angiogenesis
what is the media’s role? and what is it composed of?
it is composed of vascular smooth muscle and it regulates vascular tone by undergoing contraction and relaxation
is the regulation of contraction and relaxation of vascular smooth muscle endothelium dependent? or independent?
can be both
what is the adventitia made of?
it is made of collagen, elastin and other ECM interspersed with fibroblasts
what is the external elastic lamina?
layer of interwoven elastinfibrils between adventitia and the media
what do the adventitia and the external elastic lamina do?
contribute to the compliance of a blood vessel by producing structural ECM proteins that regulate vascular compliance
what are a few vasorelaxants?
nitric oxide (NO), prostacyclin (PGI2), natriuretic peptides
what are a few vasocontrictors?
endothelin-1 (ET-1), angiotensin II, thromboxane
what produces nitric oxide? and what enzyme is used to produce it?
L-arginine used nitric oxide synthase to produce nitric oxide
how does nitric oxide induce vasorelaxation?
via the activation of soluble guanylyl cyclase which generate cyclic guanosine monophosphate
where, from what and by what is produces prostacyclin?
produced in endothelial cells from arachidonic acid by cyclooxygenate enzymes
how does prostacyclin induce vasorelaxation?
activates specific cell surface receptor that activate adenylyl cyclase and thereby elevate cyclin adenosine monophosphate levels
it also activates potassium channels and increase influx of K+ causing membrane hyperpolarisation which blocks influx of calcium ions required for contraction
what produces natriuretic peptides?
synthesized by the heart, brain and other organs
what are the three types of natriuretic peptides? and where are they produced?
atrial natriuretic peptide/A-type –> produced by the heart
brain natriuretic peptide/B-type –> produced by the heart
Cellular natriuretic peptide/C-type –> produced by the heart, chondrocytes and endothelial cells
what does endothelin-1 act as?
acts as a vasoconstrictor, a pro-coagulant and activator of vascular smooth muscle proliferation and migration
what are the two types of ET-1 receptors? what are they expressed by? and what do they do?
ETA expressed by smooth muscle cells and induces vasoconstriction
ETB expressed by smooth muscle cells and endothelial cells, induces vasorelaxation by stimulating endothelial production of nitric oxide and prostacyclin
what does the ET-1 effect depend on?
ET-1 effects depend on the balance between the two receptors ETA and ETB
what does angiotensin act as?
it acts as a vasoconstrictors and a pro-inflammatory factor which increases the generation of reactive oxygen species (ROS)
how many receptors does angiotensin have? and what do they do?
2 receptors
AT1R promotes vasoconstriction by enhancing the release pf ET-1
AT2R promotes vasodilation by increasing the release of bradykinin which activates eNOS and increases NO levels
what does thromboxane act as?
it acts as a vasoconstrictor and pro-coagulant
what is angiogenesis? and how does it start?
growth of blood vessels from the existing vasculature
it s a must step process involving breaking of cell-cell adhesions
it starts when a small vessel is activated by an angiogenic stimulus
what is vasculogenesis?
differentiation of precursor cells into endothelial cells and the de novo formation of a vascular network
when a damage occurs because of wounding or inflammation, what does the activated endothelium produce?
they increase their production of pro-coagulants and decrease production of anti-coagulants
what is the difference between normal endothelium and activated endothelium?
normal endothelium –> increased production of anti-coagulants
activated endothelium –> decreased production of anti-coagulants
