Blood Vessels Flashcards
how many layers do blood vessels have
three
why do vessels have three layers
flow, size control, and reinforcement
these bring blood away from the heart
arteries
how many layers of elastic tissue do arteries have
two layers(tunica interna and tunica media)
what type of flow is in arteries
pulsitile and pressurized
smooth flow layer of arteries
tunica interna (internal)
smooth muscle layer of arteries
tunica media (middle)
connective tissue layer of arteries, protective covering
tunica externa
what causes blood pressure problems in the arteries
loss of elasticity, inability to stretch and recoil, occurs with age
what helps pressurize the flow in arteries
smooth muscle in turnica media
these return blood to the heart
veins
these are less complex than arteries
veins
have a relatively low pressure
veins
how do the layers of the veins differ from the layers of arteries
the layers in the veins have no elastic tissue and less smooth muscle
is the lumen bigger in the veins or arteries
veins
what keeps the blood flow one directional
valves
why do the veins need valves
due to the low pressure
what are the smallest blood vessels
capillaries
these have an endothelial layer, single cell layer and are not thick
capillaries
this is the reduction in diameter of vessels by contraction of smooth muscle
vasoconstriction
what creates resistance and slows down the flow
branches(arterioles)
why are the arterioles important in relation to the capillaries
they slow the flow and decrease the pressure which prevents the capillaries from bursting and allows more time for gas exchange
what puts the “brakes” on flow
arterioles
why does blood pressure exist
to create blood flow
another word for veins
capacitant vessels
this in veins allows for more blood capacity
big lumen
each type of vessel has an _______ suited to its _______
anatomy; function
capillary sphincters and metarterioles shunts control_____ __________
local microcirculation
where do capillaries work together
capillary beds
what do capillary beds have around them
sphincters
amount of smooth muscle in capillaries
not very much
when tissue is active, capillaries ______ and sphincters _______
relax; open
what happens when sphincters open
blood flows through
when tissue is at rest, sphincters ______
close
because the pressure in veins is low, they rely on what
muscular pumps
what has a valve system to prevent backflow
veins
what contract and squeeze blood closer to the heart
muscular pumps
what moves in a similar way to muscular pumps
lymph fluid
when does lymph fluid not drain
in elderly people, if they sit around a lot
what is the goal of the circulatory system
blood flow (ml/min)
what is the formula for blood flow
change in pressure(from pt A- pt B)/ resistance
how do fluids flow
down the pressure gradient(from high to low)
what is it called when it is difficult for blood to flow
resistance to flow
what are the three ways resistance to flow is caused
1)viscosity thickness 2)vessel length 3)vessel diameter(1/r4)
what causes the vessel length to change and cause resistance
1) obesity 2)drag-blood cells bump off the side and slow down
what is laminar flow
sweet spot of the artery where blood flow is best
what causes the resistance in a vessel with a smaller diameter
smaller sweet spot
how does blood pressure change as it goes through the circulatory system
it is constantly declining
what is a normal blood pressure
120 systolic/80 diastolic
what is a heart contraction
systolic
what is heart relaxation
diastolic
what changes during the heart cycle
pressure and volume
during this the volume of the blood in the ventricle doesnt change, very fleeting, 100th of a second
isovolumetric contraction
clogged arteries
atherosclerosis
what causes atherosclerosis
age and fatty diet
what happens during athersclerosis
the heart has to work harder past the resistance due to plaque
what does plaque typically consist of
fats and a surrounding clot
what is it called when RBC have to go around clot and subsequently get slowed down
turbulance
how are clots formed
platelets bump into the fat and clot together(snowball effect)
this is local widening of a vessel, it creates turbulence and potentially can break
aneurysm
