Cardiac Cycle and Heart Function Flashcards

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Questions and Answers

What are the two events that happen in a heartbeat?

Respiratory event

Muscular contraction (correct)

Electrical event (correct)

Blood pressure event

Why are two controlling systems required in cardiac muscle function?

To ensure organization, rhythm, and speed control for maximum efficiency.

What two systems are involved in a heartbeat?

Autonomic nervous system and nodal system.

What is the sinoatrial node?

A small mass of tissue that originates the heart rate, also known as the pacemaker. Signup and view all the answers

What is the function of the AV node?

Receives impulse from the SA node and causes ventricles to contract. Signup and view all the answers

Define the cardiac cycle.

The sequence of contraction and relaxation of heart chambers with each heartbeat. Signup and view all the answers

What happens during systole?

The heart muscle contracts, pumping blood out of the chambers. Signup and view all the answers

What occurs during diastole?

The heart muscle relaxes, allowing the chambers to fill with blood. Signup and view all the answers

What occurs during mid-to-late ventricular diastole?

Blood flows passively into ventricles Signup and view all the answers

What happens during ventricular systole?

Pressure increases Signup and view all the answers

What is the early diastole phase characterized by?

AV valves are closed Signup and view all the answers

What causes the 'Lubb' sound in the heart?

Closure of the AV valves during ventricular systole. Signup and view all the answers

What does the 'Dupp' sound signify?

Closure of the aortic and pulmonary semilunar valves during cardiac diastole. Signup and view all the answers

What is an electrocardiogram?

A record of the electrical activity of the myocardium. Signup and view all the answers

What is stroke volume?

The volume of blood pumped from the left ventricle per beat. Signup and view all the answers

What is cardiac output?

The amount of blood pumped out by each ventricle of the heart in 1 minute. Signup and view all the answers

What is the equation for cardiac output?

Heart Rate x Stroke Volume. Signup and view all the answers

Study Notes

Heartbeat Events

Two main events occur during a heartbeat: electrical events and muscular contractions.

Heart Regulation Systems

The heart requires two control systems for optimal function:
- Autonomic Nervous System (ANS) regulates heart rate and strength of contractions.
- Nodal System (Intrinsic conduction system) coordinates muscle cell contractions.

Key Structures

Sinoatrial Node (SA Node): Located in the right atrium, acts as the heart’s natural pacemaker, initiating the heartbeat.
Atrioventricular Node (AV Node): Found at the base of the right atrium, it receives impulses from the SA node and triggers ventricles to contract.

Cardiac Cycle Phases

Cardiac Cycle: The sequence of contraction (systole) and relaxation (diastole) of heart chambers during each heartbeat.
Systole: A phase where the heart muscle contracts, pumping blood out of its chambers.
Diastole: A phase where the heart muscle relaxes, allowing the chambers to fill with blood.

Diastole Stages

Mid-to-Late Ventricular Diastole: Characterized by complete relaxation, low pressure, and passive blood flow into the ventricles. Atrioventricular (AV) valves are open while semilunar (SL) valves are closed.
Early Diastole: Ventricles are completely closed for a brief moment, with AV and SL valves both closed.

Systole Stages

Ventricular Systole: Pressure rises in the ventricles, forcing the semilunar valves open and allowing blood to exit the heart. AV valves remain closed during this phase.

Heart Sounds

Lubb: The sound produced by the closure of AV valves during ventricular systole.
Dupp: The sound produced by the closure of aortic and pulmonary semilunar valves due to increased pressure during cardiac diastole.

Diagnostic Tools

Electrocardiogram (ECG): A recording of the electrical activity of the heart muscle, useful for diagnosing issues with heart rhythm and function.

Cardiac Function Measurements

Stroke Volume: The volume of blood pumped from the left ventricle with each heartbeat.
Cardiac Output: The total amount of blood discharged by each ventricle in one minute, calculated as the product of heart rate and stroke volume.

Cardiac Output Equation

Cardiac Output = Heart Rate x Stroke Volume.

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Description

Explore the fundamental concepts of the cardiac cycle, including systole, diastole, stroke volume, and the overall function of the heart. These flashcards will help you understand the events that occur during a heartbeat and the importance of cardiac muscle organization. Perfect for students of physiology and medical sciences.