12/9/08 Venous Brand Systems Utcom

Front 1

explain what and where the capacitance vessels are

Back 1

veins that can store blood due to their compliance and can shift that blood due to sympathetic innervation, thus increased tone
-such veins are in liver, spleen, lung, GI, subQ plexus; NOT vena cava)

Front 2

Head/neck venous pressure while resting, and while standing?

Back 2

rest: 15-25 mmHg
standing: -10mmHg in sagittal sinus

Front 3

what % of blood is in venules&veins? arteries&arterioles? capillaries? lung? heart?

Back 3

vv - 67%
aa - 11%
caps - 5%
lungs - 12%
heart - 5%

Front 4

describe problems if Right Atrial Pressure is above 4-7mmHg

Back 4

the veins of neck, arm, and Abdomen can increase their pressure up to about 7mmHg. thus if RAP is above 7, these veins will be distended and blood won't flow from vv. to RA

Front 5

pregnancy can lead to increased intra-abdominal pressure. what else can cause this, and what are the effects on bloodflow?

Back 5

intra-abd P can rise to ~30mmHg which can limit venous return of veins that run thru the abdomen.
also caused by - abd tumor, obesity, ascites

Front 6

describe the effect of decrease arterial pressure in regard to capacitance vessels

Back 6

baroreceptors stimulate sympa activity to capacitance veins, more venous return, more preload, more SV, higher CO, higher MAP

Front 7

In general, why doesn't gravity limit venous return when standing up vs sitting down?

Back 7

the gravity that opposes venous return also equally aids in arterial flow that is in the opposite direction, so forces cancel out. however, this isn't totally true due to compliant veins

Front 8

what leads to negative pressures in head veins? is this for supf or deep veins?

Back 8

deep veins in head will have a negative pressure as gravity pulls the blood back down into thorax. this is more for the deep veins (sagittal sinus) which remain distended, vs supf veins which "flutter" back-and-forth from collapsed/distended

Front 9

list the 4 factors affecting venous return

Back 9

-sympa tone
-limb muscle contraction
-blood volume
-respiration (increases P gradient from abd to thorax, forcing blood up)

Front 10

describe leg muscle activity in relation to leg venous valve activity

Back 10

at a standing rest, leg vein valves tend to be open as vein is distended - blood pools at feet
as leg muscles contract, they force the valves to close (i.e. work properly) which leads to more venous return and lower pedal blood pressure

Front 11

usually, usage of leg muscles will decrease pedal venous BP. when would the opposite occur?

Back 11

if there is a venous occlusion, mm contraction will force blood into the occlusion and increase venous BP

Front 12

describe the venous waves on cardiac cycle

Back 12

a - atrial contraction, slight P rise
c - ventricular contraction, slight P rise as TCV/MV bulges into atrium
v - slight P rise as atrium fills