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66 Cards in this Set
- Front
- Back
Atrial systole means
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atrial contraction begins,
atrial eject blood in ventricles |
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Give order of steps in cardiac cycle
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atrial systole
ventricular systole ventricular diastole |
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EDV stands for
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end diastolic volume
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EDV, S1 are in what step?
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atrial systole
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SV stand for + means
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Stroke volume
volume of blood ejected by ventricle through semilunar valves |
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formula for SV
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=
EDV-ESV |
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SV,
isovolumetric contractions semilumar valves close (S2) ESV ventricles release blood are in what step? |
ventricular systole
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ESV stands for
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end systolic volume
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the beginning of ventricular diastole what occurs?
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high ventricular pressure
low atrial pressure all valves closed isovolumetric relaxation |
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near the end of ventricular diastole what occurs?
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high atrial pressure
low ventricular pressure AV open passive atrial + ventricular filling begin |
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define ejection fraction
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% of EDV represented by SV
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If SV is increased?
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ventricles are ejecting more blood through semilunar valves
= increased cardio output |
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If ESV is increased?
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there is more blood left in ventricles (instead of being released through semilunar valves)
= decreased cardio output |
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ESV is usually what % of EDV?
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40%
ESV (blood ejected through semilunar valve) is 40% of EDV (blood ventricle recieved from atria) |
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S1
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first sound, lub, loud
AV close |
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S2
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second sound, dub, loud
semilunar valves close |
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atrial systole
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S1
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ventricular systole
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S2
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S3,S4
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soft sounds heard during blood flow into ventricles, atrial contraction
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sounds heard because of regurguitation of blood is
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heart mumur
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heart mumurs are caused by
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valve prolapse
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If you have a heart attack patient with an end-diastolic volume of 125 ml and an end systolic volume of 40 ml.
Calc stroke volume |
SV= EDV-ESV
SV=125-40 =85 |
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cardiac output def
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vol of blood pumped by left ventricle in 1 min
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cardiac output formula
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=
HR x SV heart rate (bpm) x stroke volume (ml/beat) |
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A patient has a heart rate of 125 beats/min, EDV of 130 mL and ESV of 40mL. What is cardiac output
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CO= HR x SV
SV= EDV-EDV 130-40=90 CO=125 x 90= 11250 mL/min |
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factors affecting heart are
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autonomic innervation
hormones |
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factors affecting stroke volume
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EDV & ESV
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Give an alternate but equal formula for CO
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=
HR x (EDV-ESV) |
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name the nervous system component in heart
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cardiac plexus
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which part of the brain also affects heart
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medulla oblongata with its
cardio acceleratory cardio inhibitory centers |
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resting tone is maintained by
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aCH (acetylocholine)
NE (norepiphrine) |
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tell flow in cardioacceltory center
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impulses sent to sympathetic neruons
cardiac plexus signal goes to AV & SA node |
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tell flow in cardioinhibitory center
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impulses sent to parasympathetic vagus
inhibitory impulses sent to heart. |
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why do pacemaker cells make the 1st heart beat?
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pacemaker cells in SA node have a membrane potential closer to threshold potential
(-60 mV instead of -80 mv) depolarizes fastest at a rate of 80 beats/min |
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sympathetic & parasympathetic stimulation is greatest at
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the SA node
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Ach is what branch of nervous system
has what effect on heart |
parasympathetic, slows heart
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NE is part of what branch of nervous system
has what effect on heart |
sympathetic, speeds up heart
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the atrial reflex is also called the
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Bainbridge reflex
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fcn of atrial reflex
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adjusts heart rate in response to increased venous return
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When you excercise how does heart increase?
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Sympathetic nervous system kicks in
stretchreceptors (mechanoreceptors) in r. atrium cause increase in HR |
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these hormones stimualte SA node and increase heart rate
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epinephrine
norepinephrine thyroid hormone |
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factors that influence Stroke Volume
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duration of ventricular diastole
(filling time) rate of blood flow during ventricular diastole (venous return) |
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preload def
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how much ventricle stretches during ventricular diastole
(aka how stretched are they before they contract (fill with blood) |
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if preload increases then, EDV
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increases
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how does preload affect muscle cells
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ability to produce tension
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at rest,
EDV is myocardium stretches stroke volume |
low
less low |
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with excercise,
EDV is myocardium stretches stroke volume |
high
more high |
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Frank Starling principle
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EDV increases
SV increases |
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the most important factor for controlling stoke volume is
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preload
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ventricula expansion is limited by
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myocardial connective tissue
cardiac (fibrous) skeleton pericardial sac |
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factors that affect ESV
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preload: how pre stretched the ventricle during diastole (rest)
contractilcity: force of contraction at a certain preload afterload: tension ventricle produces to push open semilunar |
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afterload
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tension the ventricle produces to open semilunar valve and eject blood.
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contractility def
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force produced during contraction
at a given preload |
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contractility depends on
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autonomic activty (symp/parasymp)
hormones |
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sympathetic stimulation effect on contractility
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ventricles contract with more force
increases ejection fraction decreases ESV (less blood left in ventricles that should have been pumped) |
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parasympathetic stimulation effect on contractility
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ach released by vagus nerves
reduces force of cardiac contractions |
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if afterload increases then SV
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increases
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afterload can be increased by
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any factor that restricts arterial flow
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cardiac reserve
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difference btwn resting and maximal cardiac output
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drugs that stimulate or block beta adrenergic receptors causes
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beta -one recepetors to be activated and heart rate increases
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calicum channel blockers
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decrease force of cardiac contraction
decrease BP dilate coronary arteries weaken contractions |
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what is negative ionotropic effect?
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contractions are weakened
can be due to Ca2+ channel blockers |
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EDV means
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blood recieved by venticles from atria
(aka they have to end their nap(diastole) b/c atria is giving them blood |
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ESV means
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volume of blood remaining after ventricle ejects blood through semilunar valves
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isovolumetric contraction def
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occurs in ventricles in order to pressurize blood in order to open semilunar valves
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isvolumetric contraction happens in what step?
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ventricular systole
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