Chapter 23 Flashcards
T/F venous and arterial resistance are not similiar
false
they are similar
T/F arteries and veins carry the same amount of blood
true
by the collapsible nature of the venous walls
what kind of shape of the venous system offers more flow resistance than circular shape
flattened shape
what is transmural pressure?
pressure within the vein versus pressure outside the vein
shapes of vein determined by this
T/F cross sectional area of the vein is about 3-4 times that of the corresponding artery
true
what will low transmural pressure have?
low volume of blood results in dumbbell shape
high resistance
collapsed
what will high transmural pressure have?
high volume results in circular shape
low resistance
expand
in order to expand or distend the vein from normal dumbbell shape to a circular one small or large pressure changes required?
small
once completely distended, small or large pressure ranges are required to accommdate further increases in volume
large
what is HP?
equivalent to the weight of a column of blood pressing against the vessels of the body, uses the heart as a reference point
what is the HP at the heart?
0
what is the formula for HP?
HP= pgh
p=specific gravity of blood
g= acceleration due to gravity
h=distance from the heart
when standing HP below the heart is?
higher
add pressure
body parts above the heart are?
negative
subtract pressure
what are factors that affect venous flow?
muscle pump
repiration
T/F veins are not reservoirs for blood collection
false
does the muscle contract or distend when blood is pushed toward the heart
contracts
what will an effective calf muscle pump have?
blood moves from superficial to deep
competent vales prevent reflux
venous volume and pressure decreases
venous return to the heart increases
what will an ineffective calf muscle pump have?
incompetent valves causes reflux
venous volume and pressure increases
results in venous pooling and ambulatory venous HTN
what happens during inspiration?
decrease in intra-thoracic pressure
increase in blood flow from upper extrem
increase in intra abdominal pressure
decrease blood flow from lower extremities
what happens during exhalation?
increase in intra-thoracic pressure
decreases blood flow in upper extrem
decrease in intra abdominal pressure
increases blood flow from lower
what is valsalva maneuver?
patient take in deep breath and holds it, then bears down as if having a bowel movement
what happens with valsalva?
intrathoraic and intraabdominal pressure increases significantly
all venous return halted
what can a valsalva maneuver compare too?
proximal compress of the lower extremities
