Ch.21 - The Circulatory System Flashcards
which vessels have thicker walls?
arteries
T/F: veins have valves
True, some do
where does gas exchange occur?
in capillary beds
what makes up capillary walls?
simple squamous epithelium (endothelium)
purpose of vasa vasorum
provides O2 to walls of larger vessels
T/F: arteries have valves
False
location of vasa vasorum
outer layer of vessels
pathway of blood flow
arteries, arterioles, capillaries, venules, veins
difference btw capillaries in arteries and veins
arterial capillaries are not spaced out, don’t have pores (space btw endothelial cells) like vein capillaries
which is deeper, veins or arteries?
arteries
what are arterioles?
connect arteries to capillaries, where pressure drop occurs
what is tunica media?
has smooth muscle that causes vasoconstriction, and relaxes for vasodilation, highly innervated (lots of nerves)
what is vascular tone?
degree of constriction of blood vessel, constrictor influences + dilator influences
what vessels do we have most control over?
arterioles
what are intrinsic factors?
local affects, constriction/dilation, hypoxia
what are extrinsic factors?
systemic/whole body affects, hormones, sympathetic innervation
difference btw capillaries in CNS and non-CNS
capillaries in CNS have tight junctions, do not have openings (blood-brain barrier)
what does ubiquitous mean
everywhere
function of capillaries
site of diffusion btw blood and interstitial fluid, gas exchange
what must you have in order to have blood-brain barrier
tight junctions in epithelial cells, preventing things from entering/exiting
describe capillary beds
tissues requiring large amt of O2 & blood (highly vascularized), some are avascular (cartilage, cornea of eye, lens, epithelia)
what tissues are avascular
cartilage, cornea of eye, lens of eye, epithelia
are ligaments and tendons vascular or avascular
slightly vascular
how does your body react to when you are hot?
superficial vascular plexus dilates to release excess heat
what is venous return
blood going back to heart
describe muscular pump
runs through skeletal muscle, contraction and relaxation of skeletal muscles surrounding deep veins to push blood upwards
describe respiratory pump
pressure changes in ventral body cavity during breathing, moves blood up towards heart.
what influences respiratory pump
increases abdominal pressure, decreases thoracic pressure
what does diaphragm do when you inhale
drops to increase abdominal pressure
what is venous reserve?
amount of blood stored while we are at rest
where can we find venous reserve?
in systemic veins & venuoles of abdominal organs (liver & spleen) and veins of the skin
how to access venous reserve?
spleen contracts to push blood out @ time of hemorrhage
what is circulatory pressure
pressure difference btw base of ascending aorta and entrance to R atrium
what is blood pressure
arterial pressure, pressure in systemic arterial circuit, bc arteries are where you feel your pulse to check blood pressure
what is capillary hydrostatic pressure?
pressure in capillary beds thats pushing stuff outside (declines along length of capillary)
what is venous pressure
pressure in veins (very low)
formula for stroke volume
end diastolic volume - end systolic volume
what is pulse pressure
rise in aortic pressure from systolic to diastolic
systolic pressure - diastolic pressure
what is bulk flow?
inc in pressure (systolic) is followed by dec in pressure (diastolic)
(blood flow in cardiovascular system)
formula for blood flow
change in pressure divided by resistance
what are sources of resistance?
blood viscosity, blood vessel length, blood vessel diameter
what does viscosity mean
state of being thick
what conditions affect blood viscosity
anemia or polycythemia
how does blood vessel length affect resistance
the longer the vessel, the more resistant
how does vessel diameter affect resistance
bigger the vessel, the less resistance
which source of resistance can be changes the quickest? where? why?
vessel diameter. arterioles. bc we have the most control of vascular tone
in what vessel does the steepest drop in blood pressure happen? why?
arterioles, bc they have the most resistance
what happens to blood vessel when volume increases?
walls expand to accommodate
where is blood flow the slowest? why?
in capillaries. bc this is site of gas exchange
describe inverse relationship btw blood flow velocity and cross-sectional area
inc in area = dec in velocity of flow, dec in area = inc in flow.
if theres more area for blood to flow through, it takes more time to pass
how do extrinsic factors affect blood flow
generally set the tone of blood flow
how to intrinsic (local) factors affect blood flow
respond immediately to demands of tissue
where does “local vasodilation” occur?
arterioles bc we have most control over them
why is there a pressure drop in arterioles?
bc they have to drain blood into capillaries which have much smaller area
