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Questions and Answers
Trace the path of a drop of blood as it travels from the vena cava through the heart and into the aorta. This should include the chambers, and the valves it passes through.
Trace the path of a drop of blood as it travels from the vena cava through the heart and into the aorta. This should include the chambers, and the valves it passes through.
Right Atrium → Tricuspid Valve → Right Ventricle → Pulmonary Valve (Semilunar) → Pulmonary Artery → Lungs → Pulmonary Vein → Left Atrium → Mitral Valve → Left Ventricle → Aortic Valve (Semilunar) → Aorta
Compare and contrast the histology of cardiac muscle to skeletal muscle. Which of the following statements are true? (Select all that apply)
Compare and contrast the histology of cardiac muscle to skeletal muscle. Which of the following statements are true? (Select all that apply)
Describe the function of intercalated discs in relation to electrical conduction within the heart.
Describe the function of intercalated discs in relation to electrical conduction within the heart.
Intercalated discs facilitate rapid diffusion of ions between cardiac muscle cells, enabling quick and coordinated spread of electrical impulses for efficient heart contraction.
Describe the function of the papillary muscles and chordae tendinae. Which of the following statements are true? (Select all that apply)
Describe the function of the papillary muscles and chordae tendinae. Which of the following statements are true? (Select all that apply)
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Compare the properties of the semilunar valves and the AV valves. Which of the following statements are true? (Select all that apply)
Compare the properties of the semilunar valves and the AV valves. Which of the following statements are true? (Select all that apply)
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At rest, what percentage of blood flow is directed to the brain?
At rest, what percentage of blood flow is directed to the brain?
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At rest, what percentage of blood flow is directed to the skeletal muscles?
At rest, what percentage of blood flow is directed to the skeletal muscles?
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During cold temperatures, the body experiences vasodilation to conserve heat.
During cold temperatures, the body experiences vasodilation to conserve heat.
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Which of the following are TWO mechanisms that cause the plateau in the action potential in cardiac muscle? (Select all that apply)
Which of the following are TWO mechanisms that cause the plateau in the action potential in cardiac muscle? (Select all that apply)
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The conduction velocity of signals through Purkinje fibers is much slower than the conduction velocity through cardiac muscle fibers.
The conduction velocity of signals through Purkinje fibers is much slower than the conduction velocity through cardiac muscle fibers.
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Which of the following statements is TRUE about relative refractory periods in cardiac muscle?
Which of the following statements is TRUE about relative refractory periods in cardiac muscle?
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Why is extracellular calcium concentration more relevant for cardiac muscle contraction compared to skeletal muscle contraction?
Why is extracellular calcium concentration more relevant for cardiac muscle contraction compared to skeletal muscle contraction?
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During a period of increased heart rate, what changes occur in the duration of the action potential plateau and the duration of systole?
During a period of increased heart rate, what changes occur in the duration of the action potential plateau and the duration of systole?
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Explain what the Frank-Starling mechanism encompasses.
Explain what the Frank-Starling mechanism encompasses.
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Trace the pathway of electrical conduction from the SA node through the epicardial surface of the heart.
Trace the pathway of electrical conduction from the SA node through the epicardial surface of the heart.
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Explain the concept of automaticity in the context of the heart’s electrical activity.
Explain the concept of automaticity in the context of the heart’s electrical activity.
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What is the intrinsic heart rate, and what factors influence it?
What is the intrinsic heart rate, and what factors influence it?
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What are the two main branches of the autonomic nervous system that influence heart function, and what effect does each have on heart rate?
What are the two main branches of the autonomic nervous system that influence heart function, and what effect does each have on heart rate?
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What is the main neurotransmitter released by the parasympathetic nervous system that influences heart rate?
What is the main neurotransmitter released by the parasympathetic nervous system that influences heart rate?
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Does tachycardia always indicate an underlying health problem?
Does tachycardia always indicate an underlying health problem?
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What is the primary function of papillary muscles in relation to the heart valves?
What is the primary function of papillary muscles in relation to the heart valves?
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Which statement accurately describes the difference between semilunar valves and AV valves?
Which statement accurately describes the difference between semilunar valves and AV valves?
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What feature of cardiac muscle cells contributes to their ability to communicate quickly?
What feature of cardiac muscle cells contributes to their ability to communicate quickly?
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How does blood distribution to the brain change during exercise?
How does blood distribution to the brain change during exercise?
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What is the primary role of the coronary arteries during periods of exercise?
What is the primary role of the coronary arteries during periods of exercise?
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What unique structural feature distinguishes cardiac muscle fibers from skeletal muscle fibers?
What unique structural feature distinguishes cardiac muscle fibers from skeletal muscle fibers?
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During resting conditions, approximately what percentage of blood flow is directed to the kidneys?
During resting conditions, approximately what percentage of blood flow is directed to the kidneys?
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What feature of semilunar valves is crucial to their function?
What feature of semilunar valves is crucial to their function?
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What is the role of L-type calcium channels in cardiac muscle action potentials?
What is the role of L-type calcium channels in cardiac muscle action potentials?
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How do Purkinje fibers compare to cardiac muscle fibers in terms of signal conduction?
How do Purkinje fibers compare to cardiac muscle fibers in terms of signal conduction?
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What defines the absolute refractory period in cardiac muscle?
What defines the absolute refractory period in cardiac muscle?
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During exercise, how does the body primarily respond to manage heat?
During exercise, how does the body primarily respond to manage heat?
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What happens to potassium ion permeability during cardiac muscle action potentials?
What happens to potassium ion permeability during cardiac muscle action potentials?
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What is the primary source of calcium for cardiac muscle contraction?
What is the primary source of calcium for cardiac muscle contraction?
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How does the cardiac cycle change with an increased heart rate?
How does the cardiac cycle change with an increased heart rate?
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What distinguishes the relative refractory period from the absolute refractory period?
What distinguishes the relative refractory period from the absolute refractory period?
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What heart rate range typically indicates that the heart is functioning normally?
What heart rate range typically indicates that the heart is functioning normally?
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Which neurotransmitter is released by sympathetic nerves to increase the heart's rate and contractility?
Which neurotransmitter is released by sympathetic nerves to increase the heart's rate and contractility?
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Which of the following disturbances indicates parasympathetic nervous system stimulation?
Which of the following disturbances indicates parasympathetic nervous system stimulation?
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How does the sympathetic nervous system increase cardiac contractility?
How does the sympathetic nervous system increase cardiac contractility?
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What condition is known as a slower than normal heart rate at rest?
What condition is known as a slower than normal heart rate at rest?
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What is the role of afterload in the heart's function?
What is the role of afterload in the heart's function?
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Which of the following scenarios indicates a higher afterload for the ventricles?
Which of the following scenarios indicates a higher afterload for the ventricles?
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How does increased afterload affect the ventricles?
How does increased afterload affect the ventricles?
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What physiological basis does the Frank-Starling mechanism rely on?
What physiological basis does the Frank-Starling mechanism rely on?
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Which structure has the fastest intrinsic rhythmical rate in the heart?
Which structure has the fastest intrinsic rhythmical rate in the heart?
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What is the intrinsic heart rate when the heart is not affected by external nervous inputs?
What is the intrinsic heart rate when the heart is not affected by external nervous inputs?
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What characterizes ectopic beats in the heart?
What characterizes ectopic beats in the heart?
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Which statement about the conduction system of the heart is true?
Which statement about the conduction system of the heart is true?
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What change occurs to the time spent in diastole when heart rate increases?
What change occurs to the time spent in diastole when heart rate increases?
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How does atrial contraction affect ventricular filling?
How does atrial contraction affect ventricular filling?
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What occurs during isovolumetric contraction of the heart?
What occurs during isovolumetric contraction of the heart?
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Which statement best describes the ejection fraction and its normal value at rest?
Which statement best describes the ejection fraction and its normal value at rest?
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What differentiates the 'period of rapid ejection' from the 'period of slow ejection'?
What differentiates the 'period of rapid ejection' from the 'period of slow ejection'?
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During the cardiac cycle, how do the pressures in the right and left ventricles compare during systole?
During the cardiac cycle, how do the pressures in the right and left ventricles compare during systole?
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What role does preload play in the cardiac cycle?
What role does preload play in the cardiac cycle?
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What initiates the 'period of rapid filling of the ventricles'?
What initiates the 'period of rapid filling of the ventricles'?
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Study Notes
Cardiovascular System (Week 4)
- Cardiac Anatomy and Function: Blood travels from the vena cava through the heart to the aorta, passing through specific chambers and valves. The path includes the right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, lungs, pulmonary vein, left atrium, mitral valve, left ventricle, and aortic valve.
Cardiac Muscle Histology
- Cardiac vs. Skeletal Muscle: Both are striated with actin and myosin but cardiac muscle has intercalated discs, which are essential for electrical conductivity.
Intercalated Discs
- Electrical Conduction: These discs facilitate rapid ion diffusion and communication between cardiac muscle cells enabling coordinated contractions.
Papillary Muscles and Chordae Tendinae
- AV Valve Function: Papillary muscles, connected to the AV valves via chordae tendinae, prevent valve inversion during ventricular contraction, thus preventing backflow into the atria.
Semilunar Valves vs. AV Valves
- Structural Differences: Semilunar valves are stronger and have faster blood flow; they are passive structures and don't require chordae tendinae
- AV Valve Function: These valves are thinner than semilunar valves, preventing backflow into the atria.
Blood Flow Distribution at Rest
- Brain: ~15% of blood flow
- Coronary Arteries: ~5% of blood flow, crucial for cardiac muscle function. This percentage remains constant during exercise.
- Kidneys: ~25% of blood flow
- Other Sites: Other regions of the body receive proportionate blood flow, adjusting during activity and demand.
Cardiac Muscle Contractility
- Plateau in Action Potential: Cardiac muscle action potentials exhibit a plateau phase due to a prolonged influx of calcium ions. This contrasts with skeletal muscle's faster action potential.
Cardiac Muscle Fiber Conduction
- Velocity: Purkinje fibers conduct signals much faster than other cardiac muscle fibers for efficient heart contraction.
Cardiac Contraction and Refractory Periods
- Absolute Refractory Period: During this period, the heart cannot be stimulated to contract.
- Relative Refractory Period: The heart can be stimulated, but only by stronger than normal stimuli.
Extracellular Calcium
- Cardiac Muscle Contraction: Maintaining sufficient extracellular calcium is vital for cardiac muscle contraction as it's derived from that source.
Cardiac Cycle
- Heart Rate, Action Potential, and Cycle Duration: Increased heart rate shortens the plateau phase of the action potential and reduces the time spent in ventricular systole, allowing more time for diastole and filling.
- Preload: End-diastolic pressure reflecting the degree of tension on the heart before ventricular contraction.
- Afterload: Resistance in the arterial system that ventricular pressure must overcome. Higher afterload means greater pressure required for pumping.
Conduction System
- Conduction Pathway: Electrical impulses are conducted in a specific pathway through nodes and fibers to orchestrate the heartbeat. The path starts at the sinoatrial (SA) node, then travels through specific pathways leading into the ventricles.
Heart Rate Terminology
- Tachycardia: Faster than normal resting heart rate.
- Bradycardia: Slower than normal resting heart rate.
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Description
Explore the intricacies of the cardiovascular system in this Week 4 quiz. Delve into cardiac anatomy, muscle histology, and the function of essential structures such as intercalated discs and papillary muscles. Test your understanding of how blood flows through the heart and the role of valves in maintaining proper circulation.
