Session 14 Flashcards
(23 cards)
What node initiates impulses that propagate to depolarize the atrial myocardium?
SA node
What does the P wave on an ECG represent?
Atrial depolarization
What does the PR segment on an ECG indicate?
Conduction through the AV node delays
What does the QRS complex represent in an ECG?
Ventricular depolarization
What does the T wave on an ECG signify?
Repolarization of cells
What is the U wave in an ECG?
May or may not be present
What does the cardiac cycle represent?
One complete cycle of atrial and ventricular contraction and relaxation
What are the two main actions included in the cardiac cycle?
Systolic and diastolic actions
What initiates Atrial Systole?
P wave on ECG
What happens during Atrial Systole?
Atria contract, forcing blood through AV valves, filling ventricles
What is the S1 heart sound associated with?
Isovolumetric Ventricular Contraction
What occurs during Isovolumetric Ventricular Contraction?
Pressure increases, AV valves close, both valves closed
What is the result of Ventricular Ejection?
Blood discharged into aorta and pulmonary artery
What happens during Isovolumetric Ventricular Relaxation?
Pressure falls, blood flows back into ventricles, closing semilunar valves
What is Stroke Volume (SV)?
Difference between EDV and ESV
What is Ejection Fraction (EF)?
SV/EDV, normal EF is ~55-75%
What is the S2 heart sound associated with?
Isovolumetric Ventricular Relaxation
What occurs during Rapid Ventricular Filling?
AV valves open, allowing ventricles to fill
What percentage of blood passively enters the ventricles during Diastasis?
90%
Fill in the blank: The __________ is the volume of blood in the ventricles at the end of diastole.
End-diastolic volume (EDV)
Fill in the blank: The __________ is the volume of blood remaining in the ventricles after contraction.
End-systolic volume (ESV)
True or False: The AV valves are closed during Atrial Systole.
False
What is the cardiac output obtained during the Ventricular Ejection phase?
Maximal cardiac output
