Cardiac Cycle Overview Quiz

What happens during the isovolumetric contraction phase of the cardiac cycle?

Which segment of the cardiac cycle corresponds to the atrial systole?

What is indicated by the T wave on an electrocardiogram?

What initiates the transition from passive to active ventricular filling?

Why can't the plateau phase or SA node action potentials be visually detected on an EKG?

Which phases occur during the segment from QRS to T waves in the cardiac cycle?

What occurs during ventricular filling in the passive stage?

What indicate the closing of the atrioventricular valves during ventricular systole?

Plateau Phase and Systole

Plateau phase action potentials are too subtle to show on an EKG.
SA node action potentials are small and occur in a small number of cells, making them undetectable on EKG.

EKG Depiction

EKG shows depolarizations and repolarizations as they spread through the heart, seen through the skin.

Isovolumetric Contraction Phase

Ventricles begin systole with low blood pressure.
Contraction elevates blood pressure, closing atrioventricular valves (S1).
Ventricular pressure rises.
When ventricular pressure surpasses aortic pressure (80 mmHg), ventricular ejection begins.

Ventricular Filling Phase Transition

The firing of the SA node initiates the transition from passive to active ventricular filling.
The SA node's action potential spreads to the atria and, through a plateau, causes atrial systole (active stage).

Cardiac Cycle Stages (QRS-T Wave Segment)

Isovolumetric contraction and ventricular ejection occur during this period.
This period roughly corresponds to ventricular systole.

Cardiac Cycle Stages (P-QRS Wave Segment)

Active stage of ventricular filling occurs during this period.
This period roughly corresponds to atrial systole.

Cardiac Cycle Stages (T-P Wave Segment)

Isovolumetric relaxation and passive ventricular filling occur.
Ventricular repolarization (T wave) signifies the end of ventricular contraction (systole) and beginning of diastole.
The passive filling phase follows isovolumetric relaxation.

Test your knowledge on the stages of the cardiac cycle, including the plateau phase, isovolumetric contraction, and ventricular filling. This quiz addresses key concepts from physiology and EKG interpretation relevant to heart function. Challenge yourself with questions about action potentials and their significance in cardiac events!