Questions and Answers
What are the two events that happen in a heartbeat?
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?
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What is the function of the AV node?
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Define the cardiac cycle.
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What happens during systole?
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What occurs during diastole?
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What occurs during mid-to-late ventricular diastole?
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What happens during ventricular systole?
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What is the early diastole phase characterized by?
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What causes the 'Lubb' sound in the heart?
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What does the 'Dupp' sound signify?
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What is an electrocardiogram?
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What is stroke volume?
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What is cardiac output?
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What is the equation for cardiac output?
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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.
