Cardiac Cycle Flashcards
ventricular filling phase is
diastole
ventricular emptyin phase is
systole
right ventricle, only difference from left ventricle is
pressure, same volume getting pumped out
right ventricle pressure compared to left ventricle
lower
list blood flow through the heart
pg 3
what are the AV valves
Mitral valve
tricuspid valve
what are the semilunar valves
aortic valve
pulmonary valve
where is mitral valve
left side
where is tricuspid valve
right side
where is aortic valve
left
where is pulmonary valve
right
what is pulmonic
pulmonary valve
in humans tricuspid valve has how many leaflets
3
mitral and tricuspid valve, they are connected to
chordae tendinae
chordae tendinae are connected to
papillary muscles, to ventricle
papillary muscle - what is function
they dont contract valve they just stop backflow, they stop the valve from going back into the atria
forward pressure gradient _____ valve
opens
backward pressure gradient ____ valve
closes
opening and closing of valves is
passive
what opens and closes the valves
pressure
p wave corresponds to atrial
depol
qrs wave is ventricular
depol
right after you see p wave the atria
contract
t wave corresponds to ventricular
repol
right after t wave, pressure in ventricles
decreases, ventricles relax
diastole:
ventricles relaxing, filling with blood through atria
systole:
ventricles contractiong, blood ejected
systole has two distinct phases:
- isovolumetric contraction
2. ejection phase
what is normal volume in ventricles
about 120 ml
pressure in aorta is very
high
why is pressure in aorta so high
you don’t want blood flow back into heart, keeps valve closed
first thing that happens when ventricles start to contract
the pressure increases, AV valve closes
closure of AV valve begins
systole
isovolumetric contraction means
no change in volume, but they are contracting
ejection phase is the point where
ventricular pressure becomes greater than aortic pressure, so the aortic valve opens and blood is ejected into aorta
name the 4 steps in ejectino phase
1 Aortic valve opens
2 Blood rapidly ejected into aorta
3 Aortic Pressure increases
4 Ventricular volume decreases
does the ventricle empty completely
no
what are the two phases of diastole
isovolumetric relaxation
ventricular filling
what happens to pressure in ventricle in diastole
it is lower than that of atria
what happens to valves during diastole
semilunar valves close and the pressure in atria is greater, (pressure in ventricles falls)
diastole starts when what valves close
semilunar
diastole: isovolumeric:
relaxation and filling
name the three parts of isovolumeric relaxation
Rapid decrease in ventricular pressure
Both AV and semilunar valves closed
No change in volume
where is blood coming from to fill ventricles?
atrial pressures increase
ventricular pressure during diastole
can drop all the way down to 0
pressure in atria is anywhere from
4-6 (or 10 on left side)
ventricle can fill how much without atria contracting
up to 90%
diastasis:
not a lot of increased filling of ventricles, pressure are mostly equalized in ventricle and atria
atrial systole:
SA Node fires and atria depolarize and then contract
what’s the primary determinant of ventricular filling?
how much blood is in atria, how much the pressure gradient is
if you put more blood into atria what happens to pressure
pressure wil increase
systole is much ____ than diastole
shorter - about 1/3 of time in systole, about 2/3 of time in diastole
how much time is spent in systole vs. diastole
1/3 in systole
2/3 in diastole
when HR is increased, what shortens more in regards to diastole and systole
diastole
the long length of diastole is like a safeguard , explain
if hr increases, it allows the diastole to shorten and still pump out blood b/c systole doesn’t need to decrease
the faster the HR is, the more atrial contraction
contributes to filling
people who have atrial fibrulation (atrials don’t contract), at resting they are fine, but issues com ein when they
exercise
aorta is very stretchy, each time the heart contracts it ejects
a glob of blood into aorta
what two things determine pressure in aorta
volume of blood inside
compliance (how stretchy it is)
each time heart contracts and injects volume of blood into aorta, what happens
aorta stretches but pressure goes up
when is highest pressure in aorta
systole
what is highest pressure called in aorta
systolic aortic pressure
once Aortic valve closes, where does blood go once it’s in aorta?
everywhere - tissues
what happens to volume of blood in aorta when it sends blood to tissues, and what happens ot pressures
voluem decreases and pressure decreases
diastolic pressure in aorta
80
if pt has second degree heart block (droped beat, ventricles don’t contract), what happens to pressure in aorta
decreases, b/c ventricles didn’t contract
takes high pressure to get blood to brain, why
going against gravity
why do you faint
so blood can get to brain
what is incisura
notch in aortic pressure curve b/c the blood is coming backwards and snapping close the valve, to get a little pressure gradient
what is another name for incisura
dicrotic notch
what is definition of end diastolic volume
Volume of blood in ventricle at end of diastole called
what is definition of stroke volume
how much blood is ejected into aorta each beat
formula for stroke volume
End diastolic volume – End Systolic volume
what is definitino of end systolic volume
Volume of blood in ventricle at end of systole called (so after it contracts)
how much blood is usually left in ventricles after contraction
50 ml
what is definition of ejection fraction
Percentage of End Diastolic Volume ejected in each heart beat
what is normal ejection fraction
55% or more
want to increase stroke volume, how can you do it
put more blood in ventricle
leave less blood blood in the ventricle, so can contract harder and that leaves less blood
if you put more blood in ventricle, what happens
the ventricle contracts harder
pumped out 120 ml of blood into aorta vs. 70, what will change on graph
arterial pressure b/c the volume in the aorta causes the pressure
review graph
pg 22 (or any of the pages)
why are pressures lower on right side vs. left side
b/c resistance on left side is so much higher
what is preload
stretching of ventricle just before contraction
EDV (end diastolic volume)
what is afterload
“load” that the heart must eject blood against
aortic pressure
EDV is preload or afterload
preload
with high BP (hypertension) what happens to afterload
afterload is increased
what is Cardiac output
amount of blood the heart pumps in one minute
CO =
stroke volume x heart rate
what is formula for CO
stroke volume x heart rate = CO (Cardiac output)
if stroke volume is 70 ml and HR is 70 BPM what is CO?
4.9 L/min
what is venous return
flow of blood back to heart
all of the flow that comes back to the heart
under steady state conditions, venous return should equal
cardiac output
if venous return doesn’t equal cardiac output, what happens
blood accumulates in the systemic or pulmonary circulations
first heart sound is associated with closure of
AV valves
what are you actually hearing with first sound
not actually hearing the valves closing, haring the vibrations due to the valves closing
when AV valves close what has begun
systole
second heart sound is associated with the closure of
semilunar valves closing
semilunar valves closing begins
diastole
the pause you hear in Heart beat is
diastole
volume pressure diagram tells you
about same thing as the other cardiac cycle diagram but depicted in a different way
review the volume-pressure diagram
pg 27
if you increase preload what happens to the volume-pressure diagram
it will get bigger
regulation of heart rate is based upon what two controls
intrinsic & extrinsic
what does starling mechanism say
if you stretch the heart it will contract harder
ability of the haert to change its force of contraction and therefore its stroke volume in resonse to changes in
venous return
if more blood comes back to the heart, what happens
venous return increases, and it will pump it out
if you increase what will cause increased strength of contraction
Stretching heart or End diastolic volume or Atrial Pressure or Venous return
anytime the heart is stretched, it will
contract harder
the heart stretching making it contract harder is independent of
neural and humoral influences on the heart
stretching increases sensitivity off
calcium
if you put more blood in atria, what happens to atrial pressure
increases
if atrial pressure increases, when AV valve opens what happens to the blood
it fills more
what is primary determinant of how much blood is in ventricle
rapid filling phase dependent on how much blood is in atria
it takes higher ____ to fill left ventricle than it does to fill ____
pressure, right ventircle
why does it take more pressure to fill left ventricle than right
it is thicker (think about blowing up a thicker balloon)
increase in venous return causes an increase in
cardiac output
what is intrinsic control
the heart will work without nerves, includes increased venous return to increased cardiac output, stretch will increase contractility
when sympathetic nervous system is activated what two things will it do to heart
increase HR
increase strength of contraction
when parasympathetic nervous system is activated what will it do to heart
decrease heart rate
PNS innervates
SA and AV node only
SNS innervates
AV and SA and ventricles
sympathetic nerves increase stroke volume by
leaving less in - there is less blood left in ventricles when pumped out
contractility is a term referenced to say how
good/effective heart is
positivie ionotropic agent will
increase contractility
what is example of positive ionotropic agent
EPI & NE
anything that increases inotropy is increasing
contractility
parasympathetic nerves do what to heart
decrease HR
vagal means
parasympathetic
what nerves supply ventricle muscle
just ventricle muscle
how do you decrease contractility
decrease sympathetic stimulation, increase parasympathetic
if you increase extracellular K+ what happens to RMP
it becomes more positive
when the RMP becomes more positive, in terms of heart, what does this mean
AP duration is smaller, heart will not contract as forcefully
life threatening arrhythmias are due to what for potassium
hyperkalemia
decreased calcium in plasma causes
muscle wekness
increased calcium can cause
spastic muscle
low extracellular K+ does what in terms of HR
prolonged AP, QT interval is prlonged
hypothermic does what to HR
decreased HR
