092414 vascular system Flashcards
what is the progression of vasculature from the heart?
elastic arteries to muscular arteries to small arteries/arterioles to capillary bed
capillary bed to post-capillary venules to venules to medium veins to large veins
role of the vascular system
maintain QUALITY and VOLUME of extracellular fluid
blood vessel walls have 3 layers. what are they?
tunica adventitia-outer. connective tissue.
tunica media-the most variable. smooth muscle cells and connective tissue.
tunica intima-inner. endothelium. endothelial cells. simple squamous with basal lamina.
where are smooth muscle cells of the tunica media most prominent in the vascular system?
arterial side
describe the layers of heart tissue
intima-endocardium.
simple squamous endothelium with basal lamina
media-myocardium.
consists of myocytes and fibroblasts. attaches to dense connec tissue skeleton.
adventitia-epicardium.
simple squamous. also known as visceral pericardium.
what cells are the predominating type in the tunica media of the heart?
fibroblasts
what do epicardial cells give rise to?
cardiac fibroblasts
coronary arteries (endothelial cells, smooth muscle cells)
cardiac myocytes possibly
features of large thick arteries
external elastic membrane in adventitia
media is the thickest. has circular smooth muscle cells interdigitating with 40-70 elastic lamellae
intimia endothelial cells have tight jxns and pinocytotic vesicles. pinocytotic vesicles are for nutrient exchange.
fxn of elastic arteries
elastic recoil to maintain BP during diastole
which layer is thickest in large veins?
adventitia
how are medium vessels diff from large arteries?
the media has less elastin
the intima has internal elastic lamina, which is a marker for medium vessels
how many layers of sm musc cells do medium vessels have
40
fxn of medium vessels
regulate BP
how does atherosclerosis develop?
intimal plaques derived from foam cells, which take up LDL (for ex, macrophages ingest LDL. and smooth musc cells move to the intima and ingest LDL)
what are foam cells?
macrophages
smooth muscle cells that move to the intima
diff btwn medium artery and medium vein
artery has a lot more tunica media
layers of sm muscle in small artery and arteriole?
8 and 2, respectively
fxn of small arteries and arterioles
the smooth muscle cells regulate blood flow to capillary bed
how do small vessels play a role in HTN?
lipid uptake by smooth muscle cells narrows the lumen
diameter of a capillary
7.5 micrometers = 1 RBC
3 different types of capillaries
type I-continuous:
tight jxns admit proteins only smaller than 10 kDa
pinocytotic vesicles allow passage of larger proteins
type II: fenestrated
100 nm windows, which are permanenet pinocytotic vesicles
type III: sinusoidal
discontinuities
these capillaries are larger in diameter than types I and II. the diameter is about 30 micrometers.
pinocytotic vesicles are not present in capillaries where?
CNS
ex of places with continuous capillaries
CNS
heart
skel musc
lung
basically-sites where the major thing you want to transport is oxygen
sites with fenestrated capillaries
endocrine glands
GI tract
kidneys
to transport hormones, nutrients, ions
sites with sinusoidal cpillaries
bone marrow
spleen
liver
to transport whole cells
how do capillaries transport nutrients
through pinocytotic vesicles, fenestrations, discontinuities
fxns of endothelial cells
exchange gases and nutrients
secrete regulatory molecules (vasoactive factors; growth factors like FGF, PDGF, VEGF)
how does angiogenesis begin?
by targeting endothelial cell receptors like VEGFR, FGFR, TIE-2
the ligands for the above receptors are VEGF, FGF, and angiopoietin-1
bevacizumab (avastin)
anti-VEGF monoclonal antibody used to treat tumors
