NEET Biology: Regulation of cardiac activity Practice Questions
15 free multiple-choice questions on Regulation of cardiac activity (Human Physiology) for NEET Biology, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. The conduction pathway that carries the electrical impulse from the atria to the ventricles is primarily facilitated by which structure?
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Correct answer: B — AV node
The AV node (Atrioventricular node) plays a crucial role in delaying the impulse slightly before it reaches the ventricles.
Q2. Hormones like adrenaline released during stress primarily act on which part of the cardiac system to increase the heart rate?
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Correct answer: C — SA node
Adrenaline (epinephrine) stimulates the SA node, leading to an increased rate of heartbeat.
Q3. Which component of the cardiac cycle represents the phase when the ventricles are fully closed and no blood is moving between the atria and ventricles or ventricles and arteries?
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Correct answer: A — Isovolumetric contraction
Isovolumetric phases (relaxation and contraction) occur when the volume inside the ventricles remains constant as the valves are closed.
Q4. Which component of the cardiovascular system is most directly involved in sensing changes in blood pressure and initiating compensatory reflexes?
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Correct answer: C — Baroreceptors
Baroreceptors, located in the walls of major arteries, detect stretch and signal the brainstem to adjust the activity of the autonomic nervous system to maintain blood pressure.
Q5. Which autonomic nerve primarily exerts a parasympathetic influence on the heart, slowing down its rate?
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Correct answer: C — Vagus nerve
The Vagus nerve (Cranial Nerve X) is the main component of the parasympathetic system, which acts to slow down the heart rate (negative chronotropy).
Q6. The vagus nerve (Cranial Nerve X) primarily plays which role in regulating heart rate?
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Correct answer: C — Decreasing the rate of sympathetic stimulation
The vagus nerve exerts parasympathetic control, which acts to slow down the heart rate by reducing the rate of excitation of the pacemaker cells.
Q7. The electrical impulse for cardiac contraction is primarily generated by which structure in the heart?
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Correct answer: B — SA node
The SA node (Sinoatrial node) is the primary pacemaker that sets the rhythm for the heart.
Q8. Baroreceptors located in the walls of large arteries monitor blood pressure. If blood pressure increases, the reflex response typically aims to:
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Correct answer: A — Decrease the release of sympathetic hormones
When blood pressure is high, baroreceptors signal the brainstem to decrease sympathetic output and increase parasympathetic activity to lower the heart rate and force.
Q9. Which part of the heart is primarily responsible for setting the rhythm and pace of the heartbeat (pacemaker)?
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Correct answer: A — Sinoatrial (SA) node
The Sinoatrial (SA) node, located in the upper wall of the right atrium, acts as the primary pacemaker, generating the electrical impulse that initiates the cardiac cycle.
Q10. Which hormone is generally responsible for increasing the rate of cardiac contraction and blood pressure in response to stress?
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Correct answer: B — Adrenaline
Adrenaline (epinephrine) is a major stress hormone that acts rapidly on the heart to increase heart rate and contractility.
Q11. Which part of the cardiac cycle is characterized by ventricular relaxation and the completion of ventricular filling?
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Correct answer: D — Diastole
Diastole is the phase of relaxation in the ventricles and the period when the ventricles fill with blood.
Q12. Which systemic factor, when severely decreased, can lead to a reflex increase in heart rate to maintain adequate tissue perfusion?
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Correct answer: B — Systemic blood pressure
A drop in systemic blood pressure triggers baroreceptor reflexes, which signal the cardiovascular control centers to increase sympathetic activity, thereby raising the heart rate to boost cardiac output.
Q13. The vagus nerve (parasympathetic system) primarily acts on the heart to which effect?
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Correct answer: D — Decrease the heart rate and contractility
The vagus nerve releases acetylcholine, which slows down the heart rate (negative chronotropy) and reduces the force of contraction.
Q14. The overall volume of blood pumped by the heart per minute is known as:
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Correct answer: A — Cardiac Output
Cardiac Output (CO) is the total volume of blood pumped by the heart per minute, calculated as Heart Rate multiplied by Stroke Volume.
Q15. The baroreceptors primarily monitor blood pressure and signal the brain to adjust cardiac output. Which major effect is primarily mediated by this reflex to maintain blood pressure?
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Correct answer: B — Decreasing heart rate
When blood pressure rises, baroreceptors signal the autonomic nervous system to slow down the heart rate (decreased heart rate) to restore balance.
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