Cardiac Cycle: Phases, Heart Sounds, and Physiology

Question 1

What primary event in the cardiac cycle triggers the first heart sound (S1)?

Accepted Answer

Closure of atrioventricular valves

Answer

Opening of atrioventricular valves

Answer

Opening of semilunar valves

Answer

Closure of semilunar valves

Question 2

Which of the following factors does not influence heart rate?

Accepted Answer

Blood pressure levels

Answer

Activity of the autonomic nervous system

Answer

Body temperature

Answer

Hormone concentrations

Question 3

During which phase of the cardiac cycle do the ventricles relax and fill?

Accepted Answer

Diastole

Answer

Systole

Answer

Isovolumetric contraction

Answer

Isovolumetric relaxation

Question 4

What is the primary purpose of the sinoatrial node (SA node)?

Accepted Answer

Initiation of the electrical impulse for cardiac contraction

Answer

Regulation of the rate of cardiac contraction

Answer

Coordination of atrial contraction

Answer

Prevention of retrograde conduction

Question 5

What is a typical resting heart rate range for an adult?

Accepted Answer

60-100 bpm

Answer

50-60 beats per minute (bpm)

Answer

70-120 bpm

Answer

80-140 bpm

Question 6

What is the term for the electrical signal that causes cardiac muscle contraction?

Accepted Answer

Action potential

Answer

Depolarization wave

Answer

Repolarization wave

Answer

Conduction pathway

Question 7

Which type of blood vessel carries oxygenated blood away from the heart?

Accepted Answer

Arteries

Answer

Veins

Answer

Capillaries

Answer

Lymphatics

Question 8

What is the function of the coronary arteries?

Accepted Answer

Supplying oxygen and nutrients to the heart muscle

Answer

Draining blood from the heart muscle

Answer

Regulating blood pressure

Answer

Transporting hormones

Question 9

Which heart sound is associated with the closure of the mitral and tricuspid valves at the BEGINNING of ventricular systole?

Accepted Answer

S1

Answer

S2

Answer

S3

Answer

S4

Question 10

Which of the following factors would most likely increase the heart rate?

Accepted Answer

Increased sympathetic nervous system activity

Answer

Decreased blood pressure

Answer

Hypoxia

Answer

Hyperkalaemia

Question 11

What is the primary role of the sinoatrial node (SA node) in the cardiac cycle?

Accepted Answer

It initiates the electrical impulse that triggers atrial contraction

Answer

It regulates the heart rate

Answer

It coordinates the contraction of the ventricles

Answer

It controls the flow of blood through the valves

Question 12

Which phase of the cardiac cycle involves the forceful contraction of the ventricles, leading to the ejection of blood?

Accepted Answer

Ventricular systole

Answer

Atrial diastole

Answer

Isovolumic relaxation

Answer

Rapid ventricular filling

Question 13

Which neurotransmitter is primarily released at the SA node to stimulate an increase in heart rate?

Accepted Answer

Norepinephrine

Answer

Acetylcholine

Answer

Dopamine

Answer

Serotonin

Question 14

In an Electrocardiogram (ECG), which wave corresponds to the systole phase of the cardiac cycle?

Accepted Answer

QRS complex

Answer

P wave

Answer

T wave

Answer

U wave

Question 15

During the systole phase of the cardiac cycle, which of the following occurs?

Accepted Answer

Semilunar valves close

Answer

Atrioventricular valves open

Answer

Ventricle muscles relax

Answer

Blood enters the ventricles from the atria

Question 16

What is the primary function of the atrioventricular valves?

Accepted Answer

Prevent blood from flowing back into the atria during ventricular contraction

Answer

Allow blood to flow from the ventricles into the pulmonary artery

Answer

Prevent blood from flowing back into the ventricles during atrial contraction

Answer

Ensure coordinated opening and closing of the heart valves

Question 17

What is the primary function of the left ventricle in the cardiac cycle?

Accepted Answer

To pump blood to the body

Answer

To pump blood to the lungs

Answer

To receive blood from the right atrium

Answer

To provide electrical impulses to the heart

Question 18

What is the function of the endocardium in the cardiac cycle?

Accepted Answer

Lines the interior of the heart chambers

Answer

Prevents blood leakage from the heart valves

Answer

Conducts electrical impulses throughout the heart

Answer

Regulates the secretion of hormones

Question 19

What is the primary function of the sinoatrial node?

Accepted Answer

Generating the electrical impulse that triggers the cardiac cycle

Answer

Pumping blood into the aorta

Answer

Allowing blood to flow from the atria to the ventricles

Answer

Preventing backflow of blood into the atria

Question 20

Which is NOT a heart sound?

Accepted Answer

P2

Answer

S1

Answer

S2

Answer

S3

Question 21

Which phase of the cardiac cycle involves relaxation and filling of the ventricles?

Accepted Answer

Diastole

Answer

Systole

Answer

Ischemia

Answer

Reperfusion

Question 22

What is the electrical impulse that triggers ventricular contraction called?

Accepted Answer

Cardiac action potential

Answer

Purkinje fiber

Answer

Sinoatrial node impulse

Answer

Electrocardiogram

Question 23

What is the primary function of the papillary muscles?

Accepted Answer

Preventing prolapse of the mitral valve

Answer

Generating the electrical impulse that triggers the cardiac cycle

Answer

Regulating blood flow through the aorta

Answer

Pumping blood into the pulmonary artery

Question 24

Which type of arrhythmia is characterized by an abnormally fast heart rate?

Accepted Answer

Tachycardia

Answer

Bradycardia

Answer

Fibrillation

Answer

Ventricular standstill

Question 25

What is the purpose of the cardiac reserve?

Accepted Answer

To enhance the heart's ability to pump blood under increased demand

Answer

To ensure a continuous oxygen supply to the heart

Answer

To prevent the development of heart disease

Answer

To regulate blood pressure

Question 26

What factor can lengthen the cardiac cycle?

Accepted Answer

Increased vagal nerve activity

Accepted Answer

Reduced heart muscle contraction strength

Answer

Increased sympathetic nerve activity

Answer

Elevated blood pressure

Question 27

What factor directly increases both cardiac output and systemic blood pressure?

Accepted Answer

Increased heart rate

Accepted Answer

Increased stroke volume

Answer

Increased peripheral resistance

Question 28

During which phase of the cardiac cycle do the ventricles contract?

Accepted Answer

Systole

Answer

Diastole

Answer

Isovolumetric contraction

Answer

Isovolumetric relaxation

Question 29

What is the main function of the atrioventricular valves during ventricular systole?

Accepted Answer

To prevent blood from flowing back into the atria

Answer

To allow blood to flow from the ventricles into the atria

Answer

To regulate the heart rate

Answer

To prevent regurgitation of blood into the pulmonary artery

Question 30

What physiological mechanism explains the Frank-Starling law of the heart?

Accepted Answer

Increased preload leads to increased stroke volume

Answer

Increased afterload leads to increased stroke volume

Answer

Cardiac contractility is directly proportional to preload and afterload

Answer

The heart rate is directly proportional to stroke volume

Question 31

Which of the following is a potential complication of prolonged ventricular systole?

Accepted Answer

Reduced coronary artery perfusion

Answer

Increased cardiac output

Answer

Improved myocardial oxygenation

Answer

Enhanced contractility

Question 32

What does the QT interval on an electrocardiogram represent?

Accepted Answer

The electrical depolarization and repolarization of the ventricles

Answer

The heart rate

Answer

Cardiac contractility

Answer

It is not clinically relevant

Question 33

What is the primary function of the coronary arteries?

Accepted Answer

To supply oxygenated blood to the heart muscle

Answer

To drain deoxygenated blood from the heart

Answer

To regulate heart rate

Answer

To prevent the formation of blood clots

Question 34

During the isovolumetric relaxation phase of the cardiac cycle, which event occurs?

Accepted Answer

Ventricular pressure decreases

Answer

Atrioventricular valves open

Answer

Semilunar valves close

Answer

Ventricular volume increases

Question 35

Which deflection on an electrocardiogram (ECG) represents the electrical activity during the contraction of the atria?

Accepted Answer

P wave

Answer

QRS complex

Answer

T wave

Answer

U wave

Question 36

Which heart sound is associated with the closure of the semilunar valves?

Accepted Answer

S2

Answer

S3

Answer

S4

Answer

S1

Question 37

During which phase of the cardiac cycle does the left ventricle eject blood?

Accepted Answer

Systole

Answer

Diastole

Answer

Atrial systole

Answer

Ventricular repolarization

Question 38

Which of the following is the primary function of the sinoatrial node (SA node)?

Accepted Answer

Initiates electrical impulses

Answer

Conducts electrical impulses

Answer

Regulates heart rate

Answer

Controls blood pressure

Question 39

Which of the following regulates the heart rate by releasing acetylcholine?

Accepted Answer

Parasympathetic nervous system

Answer

Sympathetic nervous system

Answer

Endocrine system

Question 40

What is the term for the electrical repolarization of the ventricles?

Accepted Answer

T wave

Answer

P wave

Answer

QRS complex

Answer

U wave

Question 41

What is the purpose of an echocardiogram?

Accepted Answer

To visualize the heart's structure and function

Answer

To perform surgery

Answer

To monitor heart rate

Answer

To measure blood pressure