Chapter 21: Blood Vessels and Hemodynamics Flashcards
what does hemodynamics do?
how blood flow is altered and distributed and how blood pressure is regulated
what occurs in the embryonic mesoderm?
where blood vessels develop from angioblasts
what is angiogenesis?
the growth of new blood vessels
how are vascular endothelial growth factors released and what is their purpose?
secreted by malignant tumors
stimulate angiogenesis to feed blood to the developing tumor
what do blood vessels form?
a closed system of tubes that carry blood away from the heart and transport it to tissues then return it to heart
what is the function of arteries?
carry blood away from the heart to the tissues
what are arterioles
smallest arteries that connect to capillaries
last vessels on arterial side of circulation
(3-6 layers)
what occurs in capillaries?
substance exchange (nutrients, wastes) between the blood and tissues through interstitial fluid by diffusion connect arteries and venules
function and structure of venules
small veins formed from several capillaries
they merge to form medium veins
connect capillaries to larger veins
what do veins do?
send blood from tissues back to heart
what is vasa vasorum?
a vessel that supplies a vessel
more common in veins
do arteries or veins have thicker wall?
ateries
what happens to arteries during ventricular systole/diastole?
systole: walls of major arteries stretch to accomodate stroke volume
diastole: arteries recoil to help control pressure and flow
what are the parts of the artery wall?
tunica intima, internal elastic lamina, tunica media, external elastic lamina, tunica externa (adventitia)
structure of the tunica intima
simple squamous epithelium
structure of the internal elastic lamina
elastin in walls, fenestrated
structure of tunica media
middle layer, smooth muscle, elastic CT
structure of tunica externa (adventitia)
outermost layer
structure of the elastic arteries aka conducting arteries
largest of arteries with more elastic fibers and less smooth muscle in walls
ex: aorta, subclavian
structure of muscular arteries aka distributing arteries
lots of smooth muscle in tunica media which distributes blood to body (40-50 layers)
ex: renal, axillary
what does vasoconstriction/vasodilation do? what causes them?
regulate blood flow and arterial blood pressure
sympathetic fibers (from medulla's vaso-motor center) cause vasoconstriction parasympathetic cause vasodilation
what are metarterioles, their function?
terminal ends of arterioles
1-2 layers of smooth muscle
control blood flow from arteries to capillaries
what is microcirculation?
flow of blood the capillaries
what allows diffusion in the cardiovascular system?
when blood is brought to the capillaries with enough pressure
what are capillary walls composed of?
1 layer of cells and basement membrane
lines with simple squamous
how many blood vessels are capillaries?
half, 50,000
how much blood can an artery hold?
capillaries capable of holding more blood than in body which is why many stay closed
what are pre capillary sphincters?
rings of smooth muscle that regulate blood flow through capillaries
sensitive to chemical changes
surround arterioles before it enters capillary