1. Ca entry thru voltage Ca channels 2. diffuse to ryanodine receptor on SR membrane 3. Ca released from SR 4. troponin interaction = contraction from shortening sarcomere (actin/myosin 5. Ca channels close (phase 3) = dec intracell Ca bc no more enters cell 6. Ca sequestered to SR by SERCA pump and out of cell by Ca exchanger (NCX) and pump

3-Cardiac Cycle Flashcards by Haley T

excitation-contraction coupling

stim for muscle contraction = depolarizing impulse
-electric events precede mechanical events
-slower/inc time delay in cardiac than skeletal muscle
-calcium induced calcium release

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calcium cycling

Ca entry thru voltage Ca channels
diffuse to ryanodine receptor on SR membrane
Ca released from SR
troponin interaction = contraction from shortening sarcomere (actin/myosin
Ca channels close (phase 3) = dec intracell Ca bc no more enters cell
Ca sequestered to SR by SERCA pump and out of cell by Ca exchanger (NCX) and pump

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sympathetic stim excitation-contraction

beta adrenergic act of muscle
inc cAMP and PKA
enhance act of Ca channels
inc intracell Ca and release from SR
enhance myosin ATPase activity
inc toponin C ‘iontropy’
inc Ca reupatake ‘lusitropy’

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inotropy

force of contraction

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lusitropy

rate of relaxation

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phases of cardiac cycle

atrial systole
isovolumic (ventricular) contraction
ejection - rapid + reduced
isovolumic (vent) relaxation
filling- rapid + reduced

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ventricular systole is what parts

contraction
isovolumic contraction + ejection

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ventricular diastole

aka relaxation
isovolumic relaxation + ventricular filling + atrial systole

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things on Wigger’s diagram

ECG
muscle tension
pressures- aortic, LV, LA
valves
phonocardiogram/heart sounds
LV volume
aortic flow

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atrial systole wave components

follows P wave + includes SOME of QRS complex

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LV pressure and volume during atrial systole

pressure slightly inc bc atrial kick adds last 20% of volume to ventricle = end diastolic volume, total filling volume

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valves during atrial systole

aortic valve closed
mitral valve open-blood entering ventricle

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sounds during atrial systole

S4
always abnormal - from forcing blood into non compliant/stiffened ventricle

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isovolumic contraction - waves

begins during portion of QRS

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pressure/volume
isovolumic contraction

LV pressure inc from ventricular muscle contraction
-volume stays the same

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valves - isovolumic contraction

-aortic closed
-mitral closed passively bc pressure differential across valve, mitral>aortic

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sounds-isovolumic contraction

S1
first heart sound from closing mitral valve vibrating chordae tendinae and blood

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rapid ejection pressure/volume

LV pressure inc more from isovolumic contraction bc still contracting

LV volume dec fastest of any phase

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rapid ejection valves

-aortic is open from pressure of other phases, need to overcome aortic pressure
-mitral closed

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rapid ejection sounds

none 0 zilch

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phase of AP corresponding to rapid ejection

phase 2, ventricle contracting

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reduced ejection waves

just before T when relaxation begins in ventricular myocardium, Ca channels close

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reduced ejection pressure and volume

LV pressure falls as muscle cells relax
LV volume dec but slower/reduced than rapid ejection
-vol at end of phase = end systolic volume, residual volume after ejection

reduced ejection valves

-aortic open as blood ejected
mitral closed

isovolumic relaxation pressure & volume

LV pressure dramatically dec since myocytes complete relax LV vol not change

isovolumic relaxation valves

both aortic and mitral closed

isovolumic relaxation sounds

S2 closure of semilunar valves = vibrations of fluid and tissue

rapid filling ECG

isoelectric line, flat myocytes are relaxed

rapid filling pressure & volume

LV pressure low (lower than LA pressure) so passive move blood from atrium to ventricle LV volume inc rapidly

rapid filling valves

aortic closed mitral open

rapid filling sounds

S3 from ventricles filling fast | can be healthy or pathologic

reduced filling ECG

isoelectric line still -myocytes relaxed ends with P wave

reduced filling pressure & volume

LV pressure low LV volume inc but slower/reduced

reduced filling valves

aortic closed mitral open

reduced filling sounds

natta

differences with right heart pump

all other cycle cards about left heart -R same events just lower pressure -only gets to 20 mmHg vs 120 on L resistance of pulmonary circ lower than systemic circ

waves of atrial pressure curve

1. a wave = contraction, H ascent before as venous return inc pressure, X descent after a wave 2. c wave = early systole, tricuspid valve bulges into RA from isovolumic contraction of vent, X' descent after 3. v wave= venous return then open AV valve, isovolumic relaxation of vent, Y descent | low yield for exam, importnat 2nd year

stroke volume is

end diastolic vol - end systolic vol amount blood ejected by heart in one beat

ejection fraction is

stroke volume (end diastolic-systolic) / end diastolic vol x 100 proportion of blood ejection with each contraction, index of cardiac fxn 65-70% normal

fractional shortening is

(end diastolic-end systolic diameter) / end diastolic diameter x100 index of cardiac contractility/myocyte shortening

relationship b/t HR and cycle duration

inverse- as HR inc CC dec diastole duration changes the most, not uniform over all phases

bookends of systole

S1 = close AV valve S2 = close semilunar

heart sounds during inspiration

S2 split into A2 and P2 P2 is delayed (comes after A2), inc venous return A2 is earlier than during expiration, dec venous return | aortic valve closes before pulmonic

wide splitting

A2 and P2 are farther apart -pulmonic stenosis pulmonic valve closes slower than normal

paradoxical splitting heart sounds

aka reverse, P2 before A2 -aortic stenosis, during expiration aortic valve close slower than normal

narrow splitting

higher resistance in pulmonary circ -hypertension, age?

blood flow | closed circulation

1. vena cava 2. R atrium 3. tricuspid valve (AV) 4. R ventricle 5. pulmonic valve (semilunar) 6. pulmonary circulation- to lungs 7. L atrium 8. mitral valve (AV) 9. L ventricle 10. aortic valve (semilunar) 11. aorta 12. systemic circulation

regurgitant murmur

from blood flow across valve when it should NOT be -regurgitant valves don't close

stenotic murmur

blood flow turbelently across valve when it normally should be -stenotic valves don't open

ejection murmur

type of systolic (b/t S1 and S2) from aortic or pulmonic valve stenosis

pansystolic/holosystolic murmur

type of systolic from regurgitant AV valve or VSD

late murmur

type of systolic murmur from mitral valve prolapse

early murmur

type of diastolic (after S2 before S1) from regurgitant aortic or pulmonic valve -if aortic then lower forward stroke volume bc blood goes back into ventricle

mid-late murmur

type of diastolic murmur from stenotic AV valve

what phases is mitral valve open

ventricular filling so 1. atrial systole 2. rapid filling 3. reduced filling