Cardiac Cycle & Sounds Flashcards
Systole
The contraction of the heart. It can be divided into atrial systole (the atria are contracting) and ventricular systole (the ventricles are contracting)
Diastole
The relaxation of the heart. It’s common to refer to ventricular diastole, but the atria do relax too
Blood pressure is therefore shown as two numbers- the systolic pressure (the pressure ___________________) and the diastolic pressure (the pressure __________________). It is always written as _________________/_________________
During contraction
At the end of diastole
Systolic
Diastolic
Three phases of ventricular systole
- Isovolumic/isovolumetric contraction
- Ventricular contraction
- Ventricular ejection
Both _______ and __________ can generate spontaneous action potentials
SA node
AV node
Under normal conditions, the ___________ is fastest and serves as the normal pacemaker for the heart
SA node
When the SA node fires, the action potential is spread through the atria (_________________)
Gap junctions
The _____________ receives the depolarization from the SA node via an ___________________________________
AV node
Internodal pathway
The AV node is ________ to conduct the action potential to the _____________, so there is a very brief “pause”
Slow
Ventricle
The ventricles are then __________________
Depolarize
The ventricles will ___________________, but the _____________ to depolarize are the _____________ to repolarize
Repolarize
Last
First
Since the atria depolarize first, they contract first-this ________________ the pressure in the atria
Increases
Atrial pressure increases
AV valves are _____________, aortic and pulmonary valves are _____________
Ventricular pressure is _______________ than atrial pressure slightly
Open
Closed
Lower
QRS complex on ECG
AV valves are ______________, aortic and pulmonary valves are _________________
Ventricular pressure is __________________________-no ejection at this point
___________________________ in atrial pressure
Open
Closed
Rising rapidly
Little increase
ST segment on ECG
AV valves are ______________, aortic and pulmonary valves are ____________
Ventricular __________________
Ventricular pressure continues to _________ and ______________ is taking place
_____________ heart sound
Closed Open Ejection Rise Ejection First
The _____________ heart sound (“lub”) is associated with closure of the ______________ valves
First
AV
What actually causes the heart sound during ventricular systole?
The sound is the result of blood in the atria hitting the closed valves as it tries to enter the ventricle. That impact creates a vibration in the cardiac tissue that can be heard
The pressure in the ventricle must ________________ the pressure in the pulmonary artery and aorta before the valves leaving the ventricles will __________
Exceed
Open
Normal aortic pressure
120/70
Normal pulmonary artery pressure
25/15
The ventricular pressure must exceed the ____________ pressure on each side to open the valve
Diastolic
T wave on ECG
AV valves are ______________, aortic and pulmonary valves are ___________
Ventricular pressure begins to _______________, blood is still ejected until the aortic valve closes
Ventricular ___________________
Closed
Open
Decrease
Repolarization
Diastole starts at heart sound _________
AV valves ______________, aortic and pulmonary valves are _______________
Ventricular pressure ________________ rapidly __________________________ atrial pressure, atrial pressure is gradually ________________ until AV valves _________
Two Closed Closed Decreases Falling below Increasing Open
Period where blood doesn’t enter or exit the ventricles
Isovolumetric relaxation
What produces the second heart sound?
When the blood in the aorta/pulmonary artery backflows and “bounces” off the closed valves
When the atrial pressure _______________ the ventricular pressure, the AV valves will open, and blood will move from the _________ to the ______________
Exceeds
Atria
Ventricles
Rapid Ventricular Filling
AV valves ________________, pulmonary & aortic valves are ________________
Blood _____________________________
Open
Closed
Enters ventricle
Venous pressure
The ___________ wave is the pressure wave created by the atrial contraction
Since there is no valve between the atria and great veins, the pressure is reflected backwards
A
Venous pressure
The ________ wave is the pressure wave created by the period of isovolumetric contraction in the ventricles-there is bulging of the wall back into the atria
C
Venous pressure
The ________ wave is the pressure wave created as blood returns back to the heart but can’t enter the ventricle
V
Heart sound due to closure of the AV valves (which signifies the onset of isovolumic contraction immediately after the QRS complex)
First heart sound
Arises from closure of the aortic and pulmonic valves at the end of ejection. It occurs near the end of the T wave and signifies the start of isovolumic relaxation
Second heart sound
Occurs at the onset of rapid ventricular filling and is due to vibration of the ventricular wall
Third heart sound
Occurs during atrial contraction and is due to vibration of the AV valve leaflets by blood flowing into the ventricle
Fourth heart sound
What are the two causes of murmurs?
Blood moving in a direction it should not be moving
Blood having a hard time moving in the direction it should be moving in
What are the two causes of systolic murmur?
Blood is moving in a direction it should not be moving-in this case, back into the atria, caused by regurgitation (mitral regurgitation)
Blood is having a hard time moving in the direction it should be moving it-in this case the blood can not get into the aorta/pulmonary artery due to stenosis
What are the two causes of diastolic murmur?
Blood is moving in a direction it should not be moving-in this case, back into the aorta or pulmonary artery, caused by regurgitation (aortic regurgitation)
Blood is having a hard time moving in the direction it should be moving it-in this case the blood can not get into the ventricle due to stenosis
