WEEK 9 MRAD 2235 Anatomy & Physiology - Cardiac Cycle

Flashcards based on key concepts from the Anatomy & Physiology lecture focused on the cardiac cycle and its electrical and mechanical aspects.

What does the P wave in an ECG represent?

Atrial depolarization.

What is the duration of one cardiac cycle at a heart rate of 75 beats per minute?

0.8 seconds.

What does the QRS complex in an ECG signify?

Ventricular depolarization.

What is the primary purpose of an electrocardiogram (ECG)?

To summarize all the electrical activity of the heart.

What happens during diastole?

Relaxation of cardiac muscle allowing the ventricles to fill with blood.

What occurs during systole?

Contraction of cardiac muscle propelling blood into the great vessels.

What defines stroke volume (SV)?

The volume of blood pumped by one ventricle with each heartbeat.

What is cardiac output (CO)?

The amount of blood pumped by each ventricle per minute.

What does the T wave in an ECG indicate?

Ventricular repolarization.

What is end diastolic volume (EDV)?

The maximum volume of blood in the ventricles at the end of diastole, approximately 135ml.

What measurement represents the volume of blood remaining in the ventricle at the end of systole?

End-systolic volume (ESV), approximately 65ml.

What is the significance of the Wiggers diagram?

It graphically represents the cardiac cycle's electrical and mechanical events.

What characterizes isovolumetric contraction?

Both mitral and aortic valves are closed, keeping ventricular blood volume constant.

What occurs during ventricular ejection?

Blood flows from the left ventricle into the aorta when left ventricular pressure exceeds aortic pressure.

What illustrates the relationship between electrical and mechanical events in the heart?

The conduction system of the heart.

What is the effect of the cardiac conduction system on heart chambers?

It causes coordinated contraction and relaxation of heart chambers.

What does a dicrotic wave represent in the cardiovascular system?

A temporary increase in aortic pressure due to the rebound of blood off the closed cusps of the aortic valve.

What occurs during atrial systole?

Atria contract, and blood is pushed into the ventricles.

What is the average normal cardiac output?

Approximately 5 liters per minute.

How does the body modulate stroke volume?

Through factors such as preload, contractility, and afterload.

What happens during the relaxation period of the heartbeat?

The ventricles and atria relax, allowing for filling.

What are the phases of the cardiac cycle?

Includes diastole and systole.

What does an increased left atrial pressure lead to?

Atrial ejection and blood entering the ventricles.

What is the relationship between heart pressure and blood flow?

Blood moves from areas of high pressure to areas of low pressure.

What is one key takeaway about the cardiac cycle and efficiency?

Left and right sides of the heart pump the same volume of blood simultaneously.

In what scenario does stroke volume increase immediately?

During physical exercise.

What diagnostic information can be analyzed from an ECG?

Heart rhythm, conduction velocity, and tissue condition.

What causes the opening of the mitral valve during ventricular filling?

When left atrial pressure exceeds left ventricular pressure.

What is the significance of the refractory periods in cardiac muscle?

To prevent tetany and ensure effective contractions.

What does the propagation of electrical activity through the heart trigger?

Coordinated contraction and relaxation of the heart chambers.

What anatomical feature prevents backflow from the aorta to the ventricles?

The aortic valve.

What physiological change does the stroke volume reflect?

The heart's efficiency in pumping blood.

How does the ECG help in diagnosing heart conditions?

Interpreting the heart's rhythm and electrical activity.

What happens to the heart chambers during diastole?

They fill with blood as pressure decreases.

What is the primary effect of the semilunar valves opening during ventricular systole?

Allows blood to flow into the great vessels.

What is an important characteristic of the heart's conduction system?

Electrical events occur slightly before mechanical events.

What role do the electrodes play in an ECG?

They measure potential differences between cardiac regions.

What does an increase in ventricular pressure indicate during systole?

The contraction and ejection of blood from the ventricles.

How is cardiac output affected during exercise?

It increases to meet higher metabolic demands.

What does the term 'cardiac cycle' encompass?

All of the events associated with one heartbeat.