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Heart as a pump Flashcards

1
Q

which valves are open in late diastole

A

mitral and R AV

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2
Q

explain what happens in late diastole

A

blood will flow from SVC to R atrium to R ventricle
blood from pulmonary veins into L atrium to L ventricle

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3
Q

phase of atria nd ventricle filling

A

late diastole

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4
Q

explain the percentages of blood nd how it travels from atria to venticles

A

70% - passively bc of low psi in ventri
30% - atrial systole

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5
Q

why is the remaining 30% need to be pumped in atrial systole

A

bc ventricles are 70% filled - not low psi anymore - needs force

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6
Q

why is there regurgitation during atrial systole

A

as atria contracts - strong - no valves present in great veins - most to ventricle some to veins - normal

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7
Q

when does AV valve close

A

during ventricular systole; towards close pa lng sa late dias and atrial sys to prople remaining 30%

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8
Q

explain why isovolume ventricular contraction is needed

A

ventricle has low psi compared to pulmo artery nd aorta - need to be high psi to overcome pulmo and aortic valves

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9
Q

explain the ventricular systole

A

1st part - isovlome contract - ventr contracts but no ejection - only to build up psi

2nd part - ventri ejection - aortic nd pulmo valces open - rapid ejection slows as systole progress

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10
Q

if psi declines in vent sys why does blood continue to flow in late systole

A

bc of momentum built up is ivc

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11
Q

how do AV valves close in vent sys

A

strentch of ventricles pull down AV valves

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12
Q

explain the volumes of blood in vent during dias and sys

A

dias 130 ml - sys 50 ml tira - 65% ejection fraction (should be pumped) - not all is pumped - 80 ml pumped

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13
Q

significance of ejection frac

A

if <65% ok for operation bc heart is strong

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14
Q

what valves close in early dias

A

aortic nd pulmonic

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15
Q

why does aortic nd pumonic close in early dias

A

psi in vent drops - high psi aorta nd pulmo art - closes to avoid backflow

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16
Q

explain the sig of IVR

A

dec in vent psi - prep for opening of mitral nd AV valves - for vent filling - dapat lower than atrial psi end when it is

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17
Q

signifies close of AV valve

A

C prime

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18
Q

what is the signifcance of the pericardium

A

Separates it from thoracic viscera

  • Pericardial sac has 5 - 30 ml clear fluid
  • Lubricates the heart
  • Permits it to contract with minimal friction
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19
Q

which atrial systole happens first

A

right before left - bc of SA node on R atrium

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20
Q

which ventric contraction happens first

A

LV before RV - L has thiccker muscle - more force to overcome in IVC so need to contract first

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21
Q

which ventric eject begins first

A

RV before LV - 10 mmHg on RV - 80 mmHG on LV

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22
Q

explain the timing of closing of pulmo nd aortic valves in respiration

A

expire - simultaneous
inspurt - aortic muna

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23
Q

why aortic valve closes slightly before pulmonic valve in inspire

A
  • psi in thorax creates suction effect that causes backflow in aorta kaya need to close first
24
Q

co of both vent are

25
what is arterial pulse
waves of blood along arteries; what we palpate
26
speeds of arterial pulse in diff arteries
4 m/s in aorta; 8 m/s in large arteries; 16 m/s in small arteries of young adults
27
when is radial pulse felt
0.1 sec after peak of systolic ejection in aorta
28
why hsould hr nd pr be =
not equal - TAO - masks out pulse
29
why is pr faster in older pt
Aging produces rigid vessels thus makes waves travel faster
30
give causes of pounding heart
palpitations - aortic insufficiency - allergic reax
31
what is dicrotic notch
Small oscillation on the falling pulse wave cause by aortic valves snaps shut
32
pulse is thready in
shock - hemmorhage
33
explain rising atrial pressure
Atrial systole - atria has to pump the remaining blood to the heart Isovolumetric contraction o AV valves bulge into the atria; because the pressure is building up in the ventricles * Blood flows in the atria until AV valves open * Seen in atrial systole, isovolumetric ventricular contraction and before AV valves are open
34
what is A wave
Due to atrial systole; Blood regurgitation o Venous inflow stops = rise in venous pressure
35
C wave
Rise in atrial pressure due to bulging of the AV valves during isovolumetric contraction
36
V wave
Rise in atrial pressure before AV valves open in diastole.
37
s1 vs s2
s1 - close AV s2 - close aortic nd pulmo valves
38
what are the patholig cheart sounds
s3 - 1/3 dias; rapid filling of vent s4- before s1; in stiff vent - psi of atria to high - vent hypertophy
39
stenosis vs insufficiency
stenosed - valve not open maayos - narrow insuff - valve does not close properly - backflow
40
timing of murmurs of aortic/pulmo valves
sten - sys induff - dias
41
timing of murmurs of mitral/tricusp
sten - dia insuff - sys
42
explain ficks principle
o Amount of substance taken up by an organ per unit time is equal to the arterial level of the substance minus the venous level (A-V difference) times the blood flow o Substance is oxygen
43
normal CO
5L/min
44
cardiac index
an organ recieves 3.2 L of blood
45
factors that control CO
hr, myocardial contractility, preload, afterload
46
CO in diff situations
no change - sleep, moderate temp change inc - anxiety - excite - 700% - hogh temp - pregy - epi dec - sitting to stand rapid - arrythmias - heart disease
47
what is + chronotrpic effect
inc co - ne and e
48
what is + inotropic action
inc co - in qual of contract - ne and e
49
relate frank starlings law to CO
Extent of the preload o More venous return, the better the stroke volume would be and multiply that with the heart rate, cardiac output will also increase * Is proportionate to the end-diastolic volume Preload, venous return, contractility of the heart will affect myocardial fiber shortening according to FrankStarling Law * If Frank-Starling Law is good, then the stroke volume will also be good * Stroke volume x heart rate = cardiac output
50
factors affecting end dia vol
* Increase o Stronger atrial contractions o Increased total blood volume o Increased venous tone o Increased pumping action of skeletal muscles o Increased negative intrathoracic pressure * Decrease o Standing o Increased intrapericardial pressure o Decreased ventricular compliance
51
exp sympathetic stim in myocardial contractility
Sympathetic stimulation Shift upward & to the left of the curve Positive chronotropic and inotropic effect
52
exp force-frequenct in myocardial contractility
Ventricular extrasystoles condition the myocardium that the next contraction is stronger Postextrasystolic potentiation ▪ Increased Ca++ availability
53
oxygen consumptions
2 ml/100g/min –heart stoppage * 9 ml/100g/min – beating heart at rest
54
what determines o2 consumption
Intramyocardial tension Contractile state of the myocardium Heart rate
55
why does o2 consumtion inc when SV inc
25% increase in SV without a change in arterial pressure produces the same increase in O2 consumption & vice versa. If there is 25% increase in stroke volume, then that 25% correlates to 7x the work of left ventricle than that of right ventricle * Pressure work produces > O2 consumption

pt momints (10 decks)

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