lecture 5: chapter 14/15 Flashcards by Emily Pereira

where is blood pressure on the circulatory system the highest

in the aorta and largerer arteries

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trtue or fals: the pressure stays constant at the aortat

true (relattively contanst)

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Why does the pressure drop significantly at the arteriole/capillary junction

They sre area of high resistances

Allows velocity to slow for echange

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true or false: the pressure in the systetmoc circulation stays constant throughout the enttire passave

false, it decrases until it is at the lowst velocity and prssure near the capillaries

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when the blood returns in the right atrium the pressure is 0 mmHH

true

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where are there lower pressure, arteriol orvenous side

venous side

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what is perpherial ressitance

the friction between the blood and vessel wall

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what is the main determinant of resistance

radius

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where is flow faster, larger or smaller vessels

faster in large

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explain why a smaller radius means a higher resistance

because there an increased surface area exposed to blood which will increase resistance (look at slie 3 from 14/15)

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what is the relationship between resistance and radius

if you increase radius, flow is 16x greater (flow=r4)

Resistamce decreases 4 fold (resistance=1/r4)

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what are some ecamples of things that increase resistance

abrupt chagnes in diametter, fatty plaques from atherosceleoriss, braching, or sharp turns

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what do abrupt changes in direction, fatty plaquest etc do in tterms of restitsncae

increase resistance and disrup laminar flow and cause turnbeunce flow

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what is turbulent flow

irregular fluid motion tthat icreases resistance

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explain why people with heart plaque have hypertension

because plaque causes bluid up in arterires with increases resistance and ie need more pressure to overcome

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explain laminar flow

during laminar flow all the vectors flow in parallel with the highestt velocity and and least friction in the center of the vessek

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what are the 3 main determinatns of resisance

blood viscocity
vessel lengtth
vassel radius

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blood is more visouc in whatt season and gender

in men and summer

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what is poiseuilles law

flow= (pie)(delta pressure)(radius)^/8nl

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what does conductance mean

how easy is is to move blood from point a tob

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what is the formular for conductance

1/resistance

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what is the problem with circualtion in series

the flow is affected by all resisatnces

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where is an area in the body where blood flows in series

in the pulmonary circulation (from heart, to lungs and back to heart)

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what is imporant about circulation in parallel

it is imporatnt for how the body regulates where the blood is going in the body
it allows for seperatet resistance paths

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what is the difference between Q and F

Q is the flow through the entire circulation | F is the flow through a certain segmaent

what is the formula for flow

q=pressure/resistance

what is the flow through a blood vessel determined by

1) the pressure difference between the two ends of the vessel 2) the resistance of the vessel

if pressure increases (and resistance is constant) what happens to the flow

it increases

if resisttance increases (and pressure is constant) what happens to the flow

flow decreases

the diastolic pressure is taken at the end of

the resting phase when the aortic valve opens

after ventricular ejecttion and pressure is decreases, why does it start to increase again

insicura increase in pressure die tto tthe bouncing off of the peripheral resistance =imporatant for filling coronary arteries

when the left ventricle contrtacts... more or less blood enters into arteriak system

more blood enters the arterial system than gets pushed onwards

what does the fact that more blood enters the arteiral system than gets oished out when the elft ventricle contrcatcts causes what

causes arteries to strettch and pressure within them rises

the highest pressure in the aorta is called..

systolic

what happens when the left ventricle relaxes (in terms of recoil)

the stretched arterial walls recold and push the contained blood onwards through the system

what pushes blood onwards into the circualtory system

the elastic recold of the arteries (compliace)

as the arteries recoil what happens to the blood and pressure

the amount of blood contained decreases and as does pressure

the lowest pressure acheived just before the next contraction is called...

diastolic pressure

what does aterial complicance mean

the ability to expand and recoil | "a change in pressure will affect a change of volume)

what is the fomrular for arterial compliace

compliance=change on volume/change in pressure

the walls of which vessel are stronger

arteries stronger than veins

which vessel has a thicker oUTER layer but less muscle

veins

which vessel has thicker walls and how

ateries are more rigid because they have more smooth msucle

the arteries are less or more distensible than the veins

less

the arteries are blank times less distensible than the veins

8 times less

an increase in pressure causes 8 times as much incrase in blood in a blank

in a vein as in an artery of comparible size

if a vein and artery are both subjected to 100 mmHG, how mich volume will be in the artery vs vein

artery: 1o0 ml | vein 800 ml

what is the reason the veins can hold more blood given the same pressure increase as a artery

because of their looser wall (with less smooth muscle), they are more distensible and compliant allowing more blood

which vessels are known as the capacitance vessels and why

veins since they are the ones that hold the blood

what does vascular distensibility mean

is the fracntional increase in volume for each mmHG rise in pressure

veins are more or less distensible than arteries

8 times more distensible

which arteries are knoen to be relatively distensble

pulmonary

what is the formula for vascular distensibility

VD= increase in volume/(icnrease in pressure)(orginal volume)

true or false : vascular distensibility isnt imporant for circualtory function

it plays an imprtant role

what does the distensible nature of the arteries allow

allows them to accomodate the pulsatile output fo the heart and to average out the pressure pulsations ] =provides smooth continous flow of blood thorugh the very small blood vessels and tissues

explain how vascular distensibility allows pulsatile to go to continous

every time a larger vessel expands and recoil it is able to flatten and dampen the pulsatile flow -=spme of the energy stored in the wall as kinetic becaomes potential aand the pressure goes forward instead of laterally

what is vascular capitance

the total capacitance of blood that can be stored in a given portion of the ciruclation for each mmHG

what is the formula for capacitance

distensibility x volume

even slight increases in venous pressures cause what

cause veins to store 0.5-1 litre of ecta blood

if there is a slight increase in pressure what does that mean veins can provide

provide a resevoir function for storing large quantities of extra blood that can be called into use whenever requred elsewhere in circualtion

true or false: the arteries serve as a resservoive for storing blood

false, the veins

the capacitance of the veins is smaller or higher than the arteries

the capacitance of veins is 24 times that of the arteries

any given change in volume within the arterial tree results in...

larger increase in pressure than in veins

what happens to the blood when veins do vasoconstriction

large quantities of blood are tranferred to the heart, therby increasing cardiac output due to an icnrease in venous return (because compliance) =more blood comes in

what is the formuka for pulse pressure

Sys. BP-diastolic BP

what are the 2 advantages of distensibiliy and compliace

1) saving energy for the heart | 2) pulsatile flow to continuous

in the pressure curve, why do we get an elongated tail and why is that beneficial

elongated tail because of the compliance (the recoil propel th blood forward so it saves work for the heart)

what is the "ohms law" for circualtion

q=delta p/r

CO is the ...

flow

what are the two sources of the pressure

mean arterial pressure and central venous pressure

what is the source of resistance in the body

systemic vascular retsiantce

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