Podcast
Questions and Answers
What happens at 0mV in the heart cells?
What happens at 0mV in the heart cells?
What is the role of slow Ca++ channels during the heart's action potential?
What is the role of slow Ca++ channels during the heart's action potential?
If not for endocrine control, how many times per minute would the SA node fire?
If not for endocrine control, how many times per minute would the SA node fire?
Which part of the heart would fire around 20 - 30 times per minute?
Which part of the heart would fire around 20 - 30 times per minute?
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What is the purpose of an Electrocardiogram (ECG)?
What is the purpose of an Electrocardiogram (ECG)?
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What is the function of the atria in the heart?
What is the function of the atria in the heart?
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Where is the base of the heart located?
Where is the base of the heart located?
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Which layer of the heart produces lubricating fluid?
Which layer of the heart produces lubricating fluid?
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What is the main function of the ventricles in the heart?
What is the main function of the ventricles in the heart?
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Which structures attach at the base of the heart?
Which structures attach at the base of the heart?
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What is the role of the auricles in the heart?
What is the role of the auricles in the heart?
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What is the main function of an artificial pacemaker?
What is the main function of an artificial pacemaker?
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During which phase of the cardiac cycle does atrial contraction occur?
During which phase of the cardiac cycle does atrial contraction occur?
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What is the main purpose of an Automatic External Defibrillator (AED)?
What is the main purpose of an Automatic External Defibrillator (AED)?
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Which wave corresponds to the repolarization of the ventricles?
Which wave corresponds to the repolarization of the ventricles?
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What happens to the semilunar valves during ventricular systole?
What happens to the semilunar valves during ventricular systole?
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What is the normal amount of blood pushed out by the ventricles in one stroke called?
What is the normal amount of blood pushed out by the ventricles in one stroke called?
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Which layer lines the chambers filled with blood, covers heart valves, and is continuous with the lining of blood vessels?
Which layer lines the chambers filled with blood, covers heart valves, and is continuous with the lining of blood vessels?
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What type of muscles do the atrioventricular valves close due to?
What type of muscles do the atrioventricular valves close due to?
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What separates the heart into chambers, and are physical extensions of myocardium?
What separates the heart into chambers, and are physical extensions of myocardium?
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What structure separates the right atrium from the right ventricle?
What structure separates the right atrium from the right ventricle?
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What is the primary function of purkinje fibers in the heart?
What is the primary function of purkinje fibers in the heart?
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Which cells in the heart have a long refractory period to prevent tetany?
Which cells in the heart have a long refractory period to prevent tetany?
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What is responsible for creating a spontaneous depolarization in cardiac conductive cells?
What is responsible for creating a spontaneous depolarization in cardiac conductive cells?
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Which feature characterizes myocardial contractile cells during depolarization?
Which feature characterizes myocardial contractile cells during depolarization?
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What is the main cause of heart murmurs?
What is the main cause of heart murmurs?
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Which event marks the closing of atrioventricular valves?
Which event marks the closing of atrioventricular valves?
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What happens in the ventricle when blood is being pushed into a stiff or hypertrophic ventricle?
What happens in the ventricle when blood is being pushed into a stiff or hypertrophic ventricle?
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What is the normal percentage range for ejection fraction?
What is the normal percentage range for ejection fraction?
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What is the formula for calculating Cardiac Output (CO)?
What is the formula for calculating Cardiac Output (CO)?
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What does the Baroreceptor reflex primarily respond to in order to regulate heart function?
What does the Baroreceptor reflex primarily respond to in order to regulate heart function?
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Which substance releases acetylcholine (ACh) to slow heart rate?
Which substance releases acetylcholine (ACh) to slow heart rate?
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What condition can decrease heart rate among the following options?
What condition can decrease heart rate among the following options?
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What effect does caffeine have on heart rate?
What effect does caffeine have on heart rate?
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Study Notes
Heart Function and Structure
- At 0mV in heart cells, the resting potential is reached, and the cell is not permeable to sodium.
- Slow Ca++ channels play a crucial role in the heart's action potential, specifically in the plateau phase.
Heart Rate Regulation
- Without endocrine control, the SA node would fire around 100 times per minute.
- The AV node would fire around 40-60 times per minute without regulation.
- The atrial rate would be around 20-30 times per minute without regulation.
Electrocardiogram (ECG)
- An ECG is used to measure the heart's electrical activity.
Heart Structure
- The atria are the upper chambers of the heart, responsible for receiving blood.
- The base of the heart is located at the top of the heart, where the atria meet.
- The epicardium produces lubricating fluid to reduce friction between the heart and surrounding tissues.
- The ventricles are the lower chambers of the heart, responsible for pumping blood throughout the body.
Blood Flow
- The atrioventricular valves close due to muscle contractions.
- The semilunar valves close during ventricular diastole.
- The stroke volume is the normal amount of blood pushed out by the ventricles in one stroke.
Heart Layers
- The endocardium lines the chambers filled with blood, covers heart valves, and is continuous with the lining of blood vessels.
Heart Conduction
- The atrioventricular valves separate the heart into chambers and are physical extensions of myocardium.
- The septum separates the right atrium from the right ventricle.
- Purkinje fibers have a primary function of conducting electrical signals rapidly, allowing for coordinated contraction.
Cardiac Cycle
- Atrial contraction occurs during the atrial systole phase of the cardiac cycle.
- The T-wave corresponds to the repolarization of the ventricles.
Cardiac Assistive Devices
- An artificial pacemaker is used to regulate heart rhythm.
- An Automatic External Defibrillator (AED) is used to restore normal heartbeat in cardiac emergencies.
Heart Function Abnormalities
- Heart murmurs are primarily caused by abnormal blood flow through the heart valves.
- The closing of atrioventricular valves marks the end of diastole and the start of systole.
- A stiff or hypertrophic ventricle increases blood pressure, making it harder for the heart to pump blood.
Cardiac Output and Blood Pressure
- The normal ejection fraction range is 55-70%.
- Cardiac Output (CO) is calculated using the formula: CO = Heart Rate x Stroke Volume.
- The Baroreceptor reflex primarily responds to changes in blood pressure to regulate heart function.
- The vagus nerve releases acetylcholine (ACh) to slow heart rate.
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Description
Test your knowledge on the physiology of cardiac muscle including topics like repolarization, calcium channels, refractory period, conduction system, and endocrine control of heart rate.