Anatomy and Physiology: The Cardiac Cycle and Conduction System
15 practice questions · 15 flashcards · made from study notes
Terms in this set (15)
- How many chambers does the human heart have?
- Four
- Deoxygenated blood from the body enters the right atrium through which two large veins?
- Superior and inferior venae cavae
- The valve between the right atrium and right ventricle is the ___ valve.
- tricuspid
- Which chamber of the heart pumps blood into the pulmonary arteries to the lungs?
- Right ventricle
- Oxygenated blood returns to the heart through the pulmonary veins and enters which chamber?
- Left atrium
- Why does the left ventricle have the thickest wall?
- Because it pumps against the high resistance of the systemic circulation.
- What is the natural pacemaker of the heart?
- Sinoatrial (SA) node
- The AV node delays the cardiac impulse briefly so that the ___ can finish emptying into the ventricles.
- atria
- What does the P wave represent on an electrocardiogram (ECG)?
- Atrial depolarization
- The QRS complex on an ECG represents ___.
- ventricular depolarization
- What is the first heart sound (S1, 'lub') caused by?
- The closing of the atrioventricular valves at the start of systole.
- Define systole.
- The phase of the cardiac cycle when the ventricles contract.
- Cardiac output is calculated by multiplying heart rate by ___.
- stroke volume
- What three factors determine stroke volume?
- Preload, contractility, and afterload.
- According to the Frank-Starling law, how does increased ventricular filling affect contraction force?
- The more the ventricle is stretched by filling, the more forcefully it contracts, within limits.
Practice questions (15)
1.Arrange the following structures to trace the path of deoxygenated blood from the body to the lungs: 1. Tricuspid valve, 2. Right ventricle, 3. Pulmonary valve, 4. Right atrium.
- A1, 4, 3, 2
- B4, 1, 2, 3
- C4, 2, 1, 3
- D2, 1, 4, 3
Show answer
Answer: 4, 1, 2, 3
This question requires the student to recall the specific sequence of blood flow through the right side of the heart, reinforcing the anatomical and functional order of the chambers and valves.
2.True or False: Blood passes through the mitral valve to enter the right ventricle.
- ATrue
- BFalse
Show answer
Answer: False
This question tests the student's knowledge of the specific valves associated with each ventricle. The mitral (or bicuspid) valve is on the left side of the heart, while the tricuspid valve is on the right.
3.Which chamber of the heart pumps deoxygenated blood to the lungs?
Show answer
Answer: The right ventricle.
This question directly assesses the student's understanding of the role of the right ventricle in the pulmonary circulation circuit.
4.Which chamber of the heart receives oxygenated blood from the lungs?
- ARight ventricle
- BRight atrium
- CLeft ventricle
- DLeft atrium
Show answer
Answer: Left atrium
This question tests the student's ability to identify the first chamber in the systemic circuit that receives newly oxygenated blood.
5.Blood leaving the left ventricle is pumped into which major blood vessel to be distributed to the rest of the body?
Show answer
Answer: The aorta.
This question assesses the student's knowledge of the connection between the heart's main pumping chamber and the body's largest artery, a critical step in systemic circulation.
6.True or False: The atrioventricular (AV) node's primary role in the cardiac conduction system is to accelerate the electrical impulse from the atria to the ventricles to ensure rapid contraction.
- ATrue
- BFalse
Show answer
Answer: False
This question challenges a common misconception. The AV node's delay is a crucial, counterintuitive feature that ensures the cardiac cycle is mechanically efficient. Understanding this detail is key to grasping the coordination between the atria and ventricles.
7.If the sinoatrial (SA) node fails to generate an impulse, what component of the cardiac conduction system will take over as the primary pacemaker, and at what intrinsic rate?
Show answer
Answer: The atrioventricular (AV) node will take over, pacing the heart at about 40 to 60 beats per minute.
This question tests the student's knowledge of the hierarchical nature of the heart's conduction system and its built-in backup mechanisms. It requires recalling specific details about the secondary pacemaker and its firing rate.
8.On an electrocardiogram, which wave or complex represents the depolarization of the ventricles, and what other electrical event is simultaneously occurring but is not visible?
Show answer
Answer: The QRS complex represents ventricular depolarization. Atrial repolarization occurs at the same time but is hidden within the QRS complex.
This question connects the electrical events of the conduction system to their graphical representation on an ECG. It requires the student to not only identify the QRS complex's meaning but also to recall the more subtle concept of why atrial repolarization is masked, demonstrating a deeper level of comprehension.
9.A patient's ECG shows a prolonged PR interval. Which part of the cardiac conduction system is causing the delay indicated by this finding?
- AAtrioventricular (AV) node
- BSinoatrial (SA) node
- CPurkinje fibers
- DBundle of His
Show answer
Answer: Atrioventricular (AV) node
This question requires the student to connect a specific ECG finding (prolonged PR interval) to its underlying physiological cause within the cardiac conduction system, as described in the text. It tests the understanding of how electrical events in the heart are represented on an ECG.
10.True or False: The T wave on an electrocardiogram represents the repolarization of the atria, which occurs at the same time the ventricles are depolarizing.
- ATrue
- BFalse
Show answer
Answer: False
This question directly tests the student's knowledge of what the T wave represents and addresses the common misconception about where atrial repolarization is seen on an ECG. It forces them to recall the specific functions of each wave as outlined in the source.
11.What electrical event in the heart corresponds to the QRS complex on an ECG, and why is the electrical event of atrial repolarization not visible as a separate wave?
Show answer
Answer: The QRS complex represents ventricular depolarization. Atrial repolarization is not seen as a separate wave because it occurs at the same time and is masked by the much larger electrical event of the QRS complex.
This question asks for two related pieces of information, requiring the student to both identify the meaning of the QRS complex and explain the absence of the atrial repolarization wave. This assesses a deeper understanding of the relative electrical magnitudes of cardiac events as presented on an ECG.
12.According to the Frank-Starling law, an increase in preload (the stretch on the ventricle from filling) will lead to what change in stroke volume and cardiac output, assuming other factors remain constant?
Show answer
Answer: An increase in preload will cause a more forceful contraction, which increases the stroke volume. This, in turn, increases the cardiac output.
This question probes the student's understanding of the Frank-Starling law, a key factor influencing stroke volume. It requires them to connect the concept of preload directly to its effect on stroke volume and then to the overall cardiac output, fulfilling the objective of identifying factors that influence this value.
13.How would an increase in afterload, such as from high blood pressure creating high resistance in the systemic circulation, likely affect stroke volume and, consequently, cardiac output?
Show answer
Answer: An increase in afterload means the ventricle has to work harder to eject blood. This increased resistance will likely decrease the stroke volume, as less blood can be pumped out against the higher pressure. A lower stroke volume would then lead to a decrease in cardiac output.
This question challenges the student to apply the concept of afterload to a clinical scenario (high blood pressure) and reason through its multi-step impact on stroke volume and cardiac output. It connects a factor influencing cardiac output to a real-world physiological state mentioned in the text (high resistance of the systemic circulation).
14.Given the description of the cardiac cycle, why is the period of isovolumetric contraction, where all four heart valves are closed, a critical phase for ensuring efficient blood ejection?
Show answer
Answer: Isovolumetric contraction is critical because it allows the pressure within the ventricles to build up significantly without any change in blood volume. This pressure must rise to exceed the pressure in the aorta and pulmonary arteries. Without this phase, the semilunar valves would not open, and blood would not be effectively ejected into the systemic and pulmonary circulations.
This question challenges the student to synthesize information about the cardiac cycle's phases (isovolumetric contraction) and the mechanics of blood flow (pressure gradients). It requires them to explain the physiological significance of a specific event, moving beyond simple definition to functional importance.
15.How might a drug that blocks the action of the vagus nerve on the heart affect a person's cardiac output at rest, assuming stroke volume remains constant?
Show answer
Answer: Blocking the vagus nerve would remove its parasympathetic (slowing) influence on the heart. This would lead to an increased heart rate. Since cardiac output is the product of heart rate and stroke volume, an increased heart rate with constant stroke volume would result in a higher cardiac output.
This question asks students to apply their knowledge of the autonomic nervous system's control over the heart to a hypothetical scenario. It requires them to connect the function of the vagus nerve, its effect on heart rate, and the formula for cardiac output to predict a physiological outcome.
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