Cardiac cycle Flashcards
what is the cardiac excitation cycle
1) action potential enters from adjacent cell
2) voltage gated ca channels open and ca enters
3) ca induces ca release trhough Ryr channels
4) local release cuases ca spark
5) sumed ca sparks create ca signal
6) ca ions bind to troponin to intial contraction
7) realation occurs when ca unbinds troponin
8) ca is pumped back in SR
9) ca is echnged with Na by the NCX tansporter
10)NA gradient is maintaned by NA/K atpase
what is a cardaic cycle
coordination of electrical and mechanical events that occur within one heartbeat
what is one cardiac cycle defined as
one period that goes from the begging of one heart beat to the begging of the next (p-p) or R-R
what are the two phases of the heart cycle and define them
systole: time of contraction
Diastole: time of relaxtation
what are the cardio vascular events recorded during the cardiac cylcle
- pressures
- ventricular volumes
- ECG
- phonocardiogram
what is the normal heart rate in adults and according to this what is the length of the cardiac cycle
- 70-75 beats /. min = 0.8s/cycle
what are the phases of the cardiac cycle bassed of og wiggers diagram
A. atrial systole
B isovolumetric ventricular contraction
C. Rapif ventricular ejection
D. SLower ventricular ejection
E. isovolumetric ventricular relaxation
F. Rapid ventricular filling
G.Slower ventricular filling
what types of pressures are recorded during the cardaic cycle
- atrial
- ventricular
- aortic
what happes during ventricular systole based on wiggers graph
- isovolumetric ventricular contraction
- Rapid ventricular ejection
- reduced ventricular ejection
what happens during ventricular diastole based on wiggers graph
- isovolumetric ventricular relaxation
- rapid ventricular filling
- reduced ventricular filling
how do the pressures of the right and left heart differ and why
- the right heart is a lower pressure pump because its a shorter circuit
- the left heart is a higher pressure pump because its a longer circuit that exerts greater resistance
what are the three waves of the atrial pressure curve
- A wave
- V wave
-C wave
what does the A wave of the atrial pressure curve represent
-what happens to atrial pressure and where is blood moving?
atrial contraction: atrial pressure increase> blood moves thorugh the ventrcles thorugh the AV valves
what percentage of ventricular filling does the atrium contribute and when is this most important
15-20% of ventricular filling and is imporntant during times of distress
what does the c wave of the atrial pressure curve represent
- occurs during isovolumetric ventricular contraction
- rapid increase in ventricualr pressure causes the AV valves to bulge inwardly» atrial volume decreases» atrial pressure increases
what does the V wave represent in the atrial pressure curve
-what happens to the AV valves
- occurs with atrial filling»_space; Av valves are closed and the atria are filling
what does the ventricular pressure curve demonstrate
changes in ventricular pressure during systole and diastole
what are the 4 phases demonstrated in the Ventricular pressure curve
- isovolumetric contraction
- ejection (systole)
- isovolumetric ventricular relaxation
- ventricular filling
what occurs during isovolumetric ventricular contraction (2) in the ventricular pressure curve
- what happens to the valves and why
What happen to the pressure
- AV valves close when LVP>LAP» ventricles begin to contract isometrically» pressure rises quickly
- when LVP > AoP» semilunar valves open» ejection of blood
what are the two phases of ejection in the ventricular pressure curve and where is blood ejected
- the two phases are rapid (3)and slower (4)ejection and and during this phase blood is pumped out if the ventricles into the aorta or pulmonary artery
what is occuring during the isovolumetric relaxation (5) phase of the ventricular pressure curve
What happens to the valves and why
What happens to the pressure
- when LVP<AoP>> semilunar valves close</AoP>
- large drop in ventricular pressure
- ventricle relaxing
whats occuring during ventricular filling phase of the ventricular pressure curve? ( 6 and &7)
- what is happens to the valves
What is the pressure in the ventricle
What phases do six and seven make up
- when LVP < LAP»_space; AV valves open
- ventricles fill with blood
- rapid filling (6) and slower filling phase (7)
- ventricular pressures reamin very low (,10mmhg) in this phase
what does the aortic pressure curve represent
- changes in aortic ( arterial pressure) during one cardiac cycle
in the aortic pressure curve what happens as the heart fill with blood ( end of diastole)
- aortic pressure declines (1)
what happens to the aortic pressure during isovolumetric ventricular contraction and what is occuring
- LVP>AoP» aortic semilunar valves open
- prior to the valves openong the pressure is at its lowest?
During isovolumetric contraction aortic pressure is at its lowest, that is right before the valves open.
when is aortic pressure the lowest?
at the end of diastole
-IS THIS HAPPENING DURING THE ISOVOLUMETRIC CONTRACTION OF THE VENTIRCLE??
what happens to aortic pressure during ejeection (3 and 4)
- what is this pressure also known as?
- what happens to the valves at the end of ejection and and why
- as blood is ejected into the aorta AoP reaches ots peak (systolic pressure)
- at the end of end of ejection LVP<AoP and aortic valves close
what does the dicrotic notch result from
-and when does it occur
the closure of the aortic valves, marking the end of ventricular systole
- occurs during isovolumetric ventricular relaxation
what does number 1 represent in the ventricular volume curve
- what does it end with
- it represent the filling phase
- ends with atrial contraction in which the blood in the atria is pushed into the ventricles
what does number 2 in the ventricular volume curve represent
- what does the volume here represent?
- isovolumetric ventricular contration
- the volume of the blood in the left ventricle is the end diastolic volume
what deos number 3 of the ventricular volume curve represent
- how much of the ventricular volume is emptied
- rapid ejection
- ## 2/3 of ventricular volume is emptied into the aorta
what does number 4 in the ventricular colume curve represent and what is happening to the ventricles and blood flow
- slower ejection
- the ventricles begin to relax and blood flows out at a slower rate
what is end systolic volume and when is it determined
the volume of blood remaining in the ventricle after ejection determined during isovolumetric ventricular relaxation
what does number 6 of the ventricular volume curve represent
- represents rapid filling when the AV valves open
- during this phase 2/3 of blood enters the ventricle
what does number 7 of the ventricular volume curve represent
- slower filling ( diastasis) in which the remaing blood enters at a much slower rate
how many sounds can be produced by the heart, how many are normal and how many are abnormal
- two are normal sounds are always heard and 2 are abnormal
what are the normal heart sounds
- the first heart sounds (s1) associated by the closure of the AV valves which is the loudest and longest heart sounds
- the second heart sound s2 results from the clousre of the semilunar valves during isovolumetric ventricular relaxation and is high pitched with low intensity
what are the abnormal heart sounds
- the third heart sound (s3) results from the rapid flow from the atria to the ventricles and is often heard in children
- the fourth heart sound (S4) occurs during atrial systole and is caused by vibrations of the ventricular wall during filling. asscoiated with disorders such as cardiac hypertrophy
what does the pressure volume loop depict
-what does the:
- red
- orange
green
- purple line define
- depicts the change in ventricular pressure and volume in one cardiac cycle
- red=isovolumetric contraction
- orange=ventricular ejection
- green=isovolumetric relaxation
- purple=ventricular filling
how do you calulate cardiac output
- stroke volume x HR
how do you calculate stroke volume
EDV-ESV
how do you calculate ejection fraction and what is the definition
stroke volume/EDV
It is the percentage of blood leaving the heart each time it squeezes
how do you calculate pulse pressure
systolic blood pressure - Diastolic blood pressure
how to calculate mean arterial blood pressure
Diastolic blood pressure + 1/3 pulse pressure
what are the cardiovascular parameters for:
- HR
- SV
-CO
BP
EF
what can valvular disorders of the left heart result in
- variation in normal blood flow patterns and heart mummurs
what should you do to identify heart murmurs
- first determine ehich valve has a structural abnormality
- determine when the valve should be closed or open
when do stenotic valve murmurs occur
- occur due to narrow valve opening
when do insufficent, regurgitent or incompetent valve mumurs occur and you get back flow into the left atrium during systole
- occur when the valve should be completely shut but is unable to close
what is mitral stenosis and when does it occur
- narrowed valve opening and occurs during ventrictular diastole when the passive filling of the left ventricle is occuring
what type of mummur results from mitral stenosis and why
results in a diastolic heart mummur due to the high restiance to blood flow from atria to the ventricles
when do opening snap murmurs occur
- occur when mitral valve opens earlier than normal due to elevated LA pressure
What is the cause of mitral stenosis
When do it develop in life
- its an acqured abnormality
- rheumatic fever is the most common cause ( strep infection)
- develops later in life ( 20 years after strep infection)
what are the 6 things mitral valve stenosis may result in
- increased LA BV
- increased LA pressure
- reduced LV filling ( decreased EDV and SV)
- left atrial hypertrophy and dialation
- atrial enlargement causing atrial fibrillatin
- elvated LA pressure may cause elvated pulmonary pressures
what can elevated pulmonary pressure from mitral stenosis result in
- pulmonary hypertenstion
- pulmonery edema
- right heart failure
What are the. Causes mitral regurgitation
- accute cardio vascular changes like rupture of the chordae tendinae
- chronic cardiovascular changes like ischemic cardiomyopathy
- mitral valve prolapse ( mitral valve bulges into the left atrium during systole)
what does mitral valve regurgitation result in
- back flow into the LA
- increased LA volume leads in to increased pressure whcih picks at the end of systole (taller V wave)
- atrial pressure peask at time of second heart sounds
- increased LA pressure cause increased pulmonary pressure
- LV hypertrophy and dialation may occur due to increased EDV
what is aortic stenosis and when does it occur
- it is narrowed valve opening occurs during ventricular systole
what is the cause of congenital aortic stenosis
When does the stenosis begin
- the aortic valve has 2 leaflets instead of 3 resulting in stenosis later in life (40s or 50s)
what is acquired aortic stenosis caused by
- in elderly patients the valve becomes clacified
what 3 things can aortic stenoisis result in
- narrowed valve causes higher afterload at the left ventricle
- an elevated ESV and reduced SV
- Left ventricular hypertrophy, myocardial
dysfunction, arrhythmias, and left heart
failure
