Questions and Answers
During the period of ventricular filling ________.
blood flows mostly passively through the atria and the open AV valves into the ventricles
If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, ________.
threshold is reached more quickly and heart rate would increase
At what point in the cardiac cycle is pressure in the ventricles the highest?
ventricular systole
Why did the changes in BP and HR occur for a patient admitted with chest pains?
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The second heart sound is heard during which phase of the cardiac cycle?
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What is the source of ATP for cardiac muscle contraction?
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The role of the coronary arteries is to __________.
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How long is the cardiac cycle, assuming the heart beats 75 times per minute?
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Cardiac tamponade results in ineffective pumping of blood by the heart because the excessive amount of fluid in the pericardial cavity will______.
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Which functional feature best describes the manner in which cardiac muscle contracts?
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What causes normal heart sounds?
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Which chamber of the heart receives oxygenated blood via the pulmonary circuit?
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Norepinephrine acts on the heart by ________.
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The presence of an incompetent tricuspid valve would have the direct effect of causing ______.
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Which portion of the electrocardiogram represents the depolarization wave received from the sinoatrial (SA) node through the atria?
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What is the suggested treatment for a patient with an improperly functioning AV node?
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Damage to the ________ is referred to as heart block.
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Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane?
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One of the changes that occurs in the pacemaker potential in the SA node is a decreased efflux of what ion?
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When threshold is reached at the SA node, what channels open causing further depolarization of the membrane?
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Repolarization of an autorhythmic cell is due to the opening of which channels?
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In order to cause cardiac muscle contraction, what causes the depolarization of the contractile cells?
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What is the difference between resting and maximal cardiac output called?
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What is an abnormally slow heart rate called?
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What is heart rate at rest under both autonomic divisions signaling called?
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What is an abnormally fast heart rate called?
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During contraction of heart muscle cells ________.
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If the vagal nerves to the heart were cut, the result would be that ________.
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Study Notes
Ventricular Filling and Heart Rate
- Ventricular filling occurs with passive blood flow from atria through open AV valves into ventricles.
- Increasing sodium influx in pacemaker cells leads to quicker threshold attainment, resulting in increased heart rate.
Cardiac Cycle Dynamics
- Ventricular systole is when pressures peak in the ventricles, reaching about 120 mm Hg.
- Changes in blood pressure and heart rate during hospital admission necessitate increased heart rate to maintain cardiac output due to decreased stroke volume.
Heart Sounds and Cardiac Contraction
- The second heart sound is produced during isovolumetric relaxation.
- Cardiac muscle contraction is powered by ATP sourced from cellular respiration and functions under automaticity, enabling spontaneous contractions.
Coronary Circulation and Cardiac Cycle Length
- Coronary arteries supply oxygenated blood to heart tissue.
- A heart rate of 75 beats per minute results in a cardiac cycle duration of 0.8 seconds.
Cardiac Tamponade and Heart Function
- Cardiac tamponade inhibits effective blood pumping due to fluid accumulation in the pericardial cavity, preventing proper ventricular filling.
Electrical Activity of the Heart
- Normal heart sounds arise from the closure of heart valves.
- The left atrium receives oxygenated blood through the pulmonary circuit.
Autonomic Nervous System Influence
- Norepinephrine quickens threshold attainment in the heart, enhancing heart rate.
- An incompetent tricuspid valve directly reduces blood delivery efficiency to the lungs.
Electrocardiogram and Heart Regulation
- The P wave on an electrocardiogram signifies atrial depolarization originating from the SA node.
- Suggested treatment for malfunctioning AV node includes the surgical implantation of an artificial pacemaker.
Heart Block and Action Potentials
- Damage to the AV node causes heart block, disrupting normal conduction.
- Autorhythmic cell action potentials spread to contractile cardiac cells via gap junctions.
Ion Movement in Pacemaker Cells
- In SA node cells, decreased potassium efflux contributes to pacemaker potential changes.
- Threshold attainment leads to the opening of fast calcium channels, causing additional depolarization.
Cardiac Muscle Contraction Mechanism
- Autorhythmic cell repolarization occurs through voltage-gated potassium channels.
- Depolarization in contractile cells is initiated by positive ion influx from adjacent cells.
Cardiac Output Capacity
- Cardiac reserve represents the difference between resting cardiac output and maximal output.
- Bradycardia refers to abnormally slow heart rates, while tachycardia indicates abnormally fast heart rates.
Influences on Heart Rate
- Vagal tone describes heart rate at rest influenced by both autonomic divisions.
- Cutting vagal nerves to the heart would elevate heart rate by approximately 25 beats per minute.
Calcium Dynamics in Contraction
- During cardiac contraction, some calcium enters from extracellular sources, triggering greater calcium release from intracellular stores.
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Description
Test your knowledge on the cardiac cycle and heart physiology with these flashcards. Each card provides key concepts about heart function, including ventricular filling and the role of pacemaker cells. Perfect for students in anatomy or physiology courses.