Questions and Answers
The P wave on the electrocardiogram represents atrial systole.
True
Cardiac output is a product of the heart rate and the end-diastolic volume.
False
The mitral valve opens when arterial pressure is greater than the ventricular pressure.
True
The movement of blood from the right ventricle to the lungs and back to the left atrium is known as the _______________ circuit.
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Atrioventricular valves close during the cardiac cycle when the...
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Calculate the cardiac reserve for the following conditions. The stroke volume is 50 ml/beat and the heart rate is 80 beats/minute in an individual at rest. During exercise, the stroke volume is 120 ml/beat and the heart rate is 130 beats/minute. The cardiac reserve is ________ L/min.
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An incompetent valve that fails to fully open is called an incompetent valve.
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The volume of blood in the ventricles at the end of the filling phase is known as the __________ volume.
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The axis labeled 'b' in this figure illustrating the electrical activity of the cardiac contractile cell is________ (label the units in parentheses).
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The portion of the graph labeled 'b' commonly called the drift, is known as the___________.
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The potentials in the figure labeled 'c', 'f' is _________
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The ions shown in 'e' are _____________ ions, whereas the ions shown in 'h' are ____________ ions.
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The potential at 'c' in the figure is __________ mV, whereas the potential at 'd' is __________ mV.
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An increase in the heart rate is due to _______ stimulation at the sinoatrial node due to an opening of __________ and __________ ion channels.
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The end-diastolic volume (EDV) is also known as the preload which is the pressure stretching the ventricle just prior to contraction.
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Total peripheral resistance (TPR; systemic vascular resistance) is the frictional resistance to blood flow throughout the venous system.
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The end-diastolic volume (EDV) is _____________ proportional to contractility of the heart and __________ proportional to the stroke volume.
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The relationship shown in the figure is known as the _______________.
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In the figure, 'a' represents _________, whereas 'b' represents ________, and 'c' results from ___________ nervous stimulation.
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An increase in venous return will increase the end-diastolic volume and result in a reduced cardiac output.
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Study Notes
Electrocardiogram and Heart Function
- The P wave on an electrocardiogram indicates atrial systole, reflecting electrical activation leading to atrial contraction.
- The mitral valve opens when arterial pressure surpasses ventricular pressure, allowing blood flow from the atrium to the ventricle.
- Atrial valves close when ventricular pressure exceeds atrial pressure, preventing backflow during ventricular contraction.
Blood Circulation and Cardiac Output
- The movement of blood from the right ventricle to the lungs and returning to the left atrium is the pulmonary circuit.
- Cardiac output (CO) at rest can be calculated as 4,000 ml/min with a heart rate of 80 beats/min and a stroke volume of 50 ml/beat.
- During exercise, cardiac output increases to 15,600 ml/min with a stroke volume of 120 ml/beat and a heart rate of 130 beats/min.
- Cardiac reserve, indicating the capacity for increased output, is 11.6 L/min, calculated from the difference between exercise and resting cardiac outputs.
Heart Valves and Performance
- An incompetent valve that does not fully open is misnamed; it should instead refer to a specific type of valve failure.
- End-diastolic volume (EDV), or preload, represents the volume of blood filling ventricles before contraction and is crucial for determining stroke volume.
- The end-diastolic volume is directly proportional to contractility and stroke volume, affecting overall heart performance.
Action Potentials and Ion Dynamics
- The pacemaker potential (PP) is the drift phase in cardiac action potentials, critical for initiating heartbeats.
- Key ion dynamics: sodium ions are associated with depolarization, while potassium ions are involved in repolarization phases of action potentials.
- The potentials at specific phases: at point 'c', the potential is -90 mV, and at point 'd', it rises to +20 mV.
Neural Control and Vascular Resistance
- An increase in heart rate is a result of sympathetic stimulation at the sinoatrial node, facilitated by HCN sodium and T-type calcium ion channels.
- Total peripheral resistance (TPR) refers to frictional resistance affecting blood flow throughout the systemic circulation, not just the venous system.
- Increased venous return boosts end-diastolic volume leading to enhanced cardiac output, contrary to some misconceptions.
Frank-Starling Law
- The Frank-Starling Law of the Heart illustrates the relationship between the end-diastolic volume and stroke volume, emphasizing how increased filling leads to stronger contractions.
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Description
Test your knowledge on the key concepts of heart function and cardiovascular physiology. This quiz covers topics such as electrocardiogram readings, cardiac output, and valve dynamics. Perfect for students studying physiology or preparing for exams.
