Cardiac Cycle & Heart Sounds Flashcards
During ventricular systole, what happens with ventricular volume and pressure
Volume decreases and pressure increases until amount of blood (volume) is depleted, then pressure begins to fall
What does ventricular systole occur on the EKG
From the QRS to the end of the T-wave
When does ventricular diastole occur on the EKG
After the Twave
What is the typical Ao. Pressure
120/80
What is the typical Ventricular pressure
120/0
The amount of blood that is ejected from the ventricles during systole is known as what
The strove volume
What does atrial contraction mean in terms of atrial pressure and volume as well as ventricular volume and pressure
Atrial pressure increases
Atrial volume decreases
Ventricular volume increases
Ventricular pressure increases
Why is the P wave included in the PR interval
Due to the delay of the muscle contraction
The electrical conduction reaves the AV Node first before mechanical contraction occurs.
After the atria contract and begin to relax, what happens with pressure and volume in in the ventricles
The ventricles start to contract and pressure increases, but volume does not change right away
The QRS complex represents what phases in ventricular conduction
Phase 0 and 1
The ST segment represents what in terms of ventricular myocyte activity
Phase 2 - the plateau
Why does the ventricular pressure drop while the ventricles are still contracting
Less blood (volume) to contract against since it’s being moved into the aorta
Why does the atrial pressure have a steady increase during ventricular systole
Passive filling of blood from venous system filling up atria and causing an increase in pressure bc AV valves are closed
The movement of calcium back out of the cell during ventricular relaxation (phase 3, repol) causes what
A release of Ca from the troponin C and relaxation of myosin
Calcium moves out of the cell via Na-Ca exchanger
During diastole, what chamber has a higher pressure
What about during systole
Atria
Ventricles
Why does aortic pressure decrease throughout atrial contraction and a little bit into ventricular contraction
Peripheral run-off
Blood flow directed to periphery
What has to happen for AV valves to open and what does this mean
Atrial pressure has to increase over the pressure of the ventricles
This means that only slight pressure from the contracting atria will open the AV valves and cause ventricular filling
What has to happen for the AV valves to close and the SLV to open in ventricular systole.
Pressure in ventricles must exceed that of the atria - to close the AV valves, and must also exceed the pressure of the Ao and PT respectively to open SLV
The period time when the ventricular volume in constant but ventricular pressure is increasing is called what? What is happening with the valves during this stage? When is this represented on the EKG
Called isovolumentric contraction
Ventricular pressure is increasing but has not overcome Ao pressure yet to open SLV
SLV and AV valves are closed
This is represented during the QRS complex
Describe how HTN would affect the flow of blood through the Ao.
HTN means higher diastolic pressure which will cause the LV to contract harder (increasing pressure) to overcome Ao pressure and open SLV to send blood to the body.
This will cause LVH
When the pressure in the ventricle drops below the arterial pressure, what happens
The AoSLV and PSLV close
Define the Dicrotic Notch
The closing of the AoSLV produces the notch in the AO pressure wave. This is peripheral divergence of blood from the Ao, while no more blood i entering the ventricles.
This notch begins the isovolumetric relaxation period
Define the isovolumetric relaxation period
No blood entering or leaving ventricles. All valves closed and ventricles are not contracting.
The period ends when the AV valves open (due to passive blood flow into the atria which also causes an increases in pressure and thus the AV valves to open) and blood begins to fill the ventricles
Why does blood rapidly fill the ventricles
The pressure and volume are so low compared to the atria, this causes a rapid passive filling
Why does Ao pressure continue to drop during diastole
Peripheral run-off
What does the A wave in the Jugular Pressure indicate
This is the pressure wave created by the atrial contraction.
It is reflected backward since there is no valve between the atria and the great veins
Define the C wave
The pressure wave in the Jugular pressure created by the period of isovolumetric contraction (AV and SLV closed) from bulging back into the atrial wall from ventricular contraction
When does the C wave end
When the AoSLV opens
Define the V wave
The pressure wave of the jugular wave that is created as blood returns back to the heart but can’t enter the ventricles yet (atrial filling and increase in atrial pressure)
The QRS complex begins when in regards to ventricular pressure
Just before ventricular pressure begins to rise, but ventricular pressure is constant (isovolumetric contraction)
Ventricular pressure starts to decline when in regards to the EKG
The beginning of the T-wave
What is the lub (S1) caused by and what does this mean physiologically
The result of blood in the atria hitting the closed valves as it tries to enter the ventricles
This means that the ventricles have already begun to contract and have increased their pressure to close the AV valves
The LUB is characteristic with atrial contraction.
What does the DUB (S2) come from and what does this mean physiologically
Produced from the back flow of blood onto the SLV
This means the ventricles have stopped contracting and thus the pressure in the Ao and Pt are now greater than that of the ventricles and have closed the SLV.
This sound is associated with ventricular contraction
Define stenosis and incompetence
Stenosis - valve doesn’t open fully - causes an increase in the chamber (LVH)
Insufficiency - valve does not close fully causing a back flow of blood into the chamber
What are the two thing that can cause a murmur in ventricular systole
Mitral valve regurgitation - blood moving back into the atria (insufficiency/incompetence)
Ao/PT stenosis - blood not moving out of ventricles well.
What can cause a murmur in ventricular diastole
Ao regurgitation - blood moving back into the Ao
AV Stenosis - blood cant get into ventricles
