Biology

Cardiovascular and Nervous System

983 Questions

Review the human cardiovascular system through these competitive exam practice questions. Key areas include heart valves, cardiac impulse pathways, and blood pressure regulation. A solid grasp of these fundamentals is crucial for science sections.

Heart anatomy and valvesCardiac impulse conductionBlood pressure mechanicsHeartbeat regulation

Cardiovascular and Nervous System Questions

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Typical 'lubb-dup' sounds heard in heart beat are due to

  1. Closing of bicuspid and tricuspid valves

  2. Closing of semilunar valves

  3. Blood under pressure through aorta

  4. Closure of bicuspid-tricuspid valves followed by semilunar valves
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Heart produces two distinct sounds that can be heard with the help of stethoscope. These are 'lubb' and 'dup'.
  • Lubb is the first sound which has a low pitch and produced by the closure of tricuspid and bicuspid valves (collectively called atrioventricular valves) at the beginning of ventricular systole.
  • Dup is the second sound which is sharp and has a high pitch. It is produced by closure of semilunar valves by the end of ventricular systole and beginning of ventricular diastole).
So, the correct answer is 'Closure of bicuspid-tricuspid valves followed by semilunar valves'.
Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The first heart sound is

  1. Lubb during closure of semilunar valves

  2. Dupp during closure of semilunar valves

  3. Lubb during closure of atrioventricular valves

  4. Dupp during closure of atrioventricular valves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
When the heart beats, it produces sounds that can be heard by stethoscope. There are four heart sounds which are designated as S1, S2, S3 and S4.
  • S1: It is the first sound 'lubb'. It has slow pitch and produced by closure of atrioventricular valves at the beginning of ventricular systole.
  • S2: It is the second sound 'dup'. It is sharper and has high pitch. It is produced by closure of semilunar valves by the end of ventricular systole. 
  • S3 and S4 are usually faint and may not be audible. S3 is produced during ventricular filling of heart and S4 is produced during atrial systole.
So, the correct answer is 'Lubb during closure of atrioventricular valves'.
Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

What will be the number of heart beats per minute, if the stroke volume of heart increases, with total volume of blood remains same

  1. Remains constant

  2. Decreases

  3. Increases

  4. Become erratic.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Cardiac output is the product of stroke volume and heart rate. If cardiac output remains relatively constant and stroke volume increases, the heart rate must decrease to maintain the same output.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Doctors use stethoscope to hear the sounds produced during each cardiac cycle. The second sound in heard when :

  1. AV valves open up

  2. Ventricular walls vibrate due to gushing in of blood from artia.

  3. Semilunar valves close down after the blood flows into vessels from ventricles.

  4. AV node recives signal from SA node.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
During each cardiac cycle, two prominent sounds are produced which can be easily heard through a stethoscope. The first sound (lub) is associated with the closure of the tricuspid and bicuspid valves during ventricular systole to prevent the backflow of blood to atria. The second sound (dub) is associated with the closure of semilunar valves during ventricular diastole to prevent the backflow of blood to ventricles.
Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The rate of heart beat is determined by

  1. SA node

  2. AV node

  3. Purkinie fibre

  4. Papillary muscles
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The SA node acts as the primary pacemaker of the heart, setting the rhythm and rate of the heartbeat. The other structures listed are part of the conduction system but do not set the primary rate.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The rate conduction of impulse in the conducting system of heart is fastest in

  1. Atrial muscles

  2. Bundle of His

  3. Purkinje's fibres

  4. AV node
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the cardiac conduction system, Purkinje fibers have the fastest rate of impulse conduction, allowing the ventricles to contract rapidly and uniformly from the apex upward.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

State whether the following statements are true or false.
Human heart is neurogenic because the heart beat originates in the nodal tissues.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The heart is entirely made up of cardiac muscles. Muscle cells are also called myocytes. The control of the heart function is by a set of muscles or special node of the modified heart muscle, the sinoatrial node (SAN) located in the atria, so the heart is, therefore, called myogenic.

So, the correct option is 'False'.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

In heart, automatic rhythmic impulse generation capability is present in the

  1. S.A. node

  2. A.V. node

  3. Bundle of His

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The human heart is a muscular structure made up of involuntary cardiac tissues. The pacemaker of the heart or the SA node generates an electrical impulse that travels across the heart muscles and results in a heartbeat. Sometimes activity of SA node is decreased  by vagus cranial nerve then AV node, Bundle of His and Purkinje fibres together provide Autorhythmicity to the heart.

So, the correct answer is 'All of the above'.
Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The heart sounds normally heard by a physician while holding a stethoscope onto the left side of the chest of the patient are due to

  1. Contraction of atrial chambers.

  2. Contraction of ventricular chambers.

  3. Closure of the atrioventricular valves.

  4. Relaxation of the semilunar valves.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In healthy adults, there are two normal heart sounds often described as a lub and a dub, that occur in sequence with each heartbeat. These are the first heart sound (S1) and second heart sound (S2), produced by the closing of the atrioventricular valves (AV) and semilunar valves respectively. 

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The heart sound 'dupp' is produced when

  1. Tricuspid valve is opened.

  2. Mitral valve is opened.

  3. Mitral valve is closed.

  4. Semi-lunar at the base of aorta get closed.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Heart sounds are heard on the surface of the chest in the heart region; they are amplified by and heard more distinctly through a stethoscope. They are caused by the vibrations generated during the normal cardiac cycle and may be produced by muscular action, valvular actions, motion of the heart, or blood passing through the heart. The second heart sound (S2) is shorter and higher pitched than the first, is heard as a dupp and is produced by closure of the aortic and pulmonary valves.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The rate of heart beat in a rabbit is nearly

  1. 92 per minute

  2. 100 per minute

  3. 150 - 300 per minute

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cardiac output is estimated by heart beat. The amount of blood pumped by the heart per minute is known as cardiac output. Small mammals have high metabolic rates so they faster heart rates than larger-sized mammals. A rabbit at rest normally has a heart rate that ranges from 140 to 180 beats per minute. Stress can cause the heart rate to increase, and the rate in a stressed rabbit can be quite high: well over 300 beats per minute. Therefore the rate of the heartbeat in a rabbit can be ~ 150-300 per minute. 

So, the correct answer is option C.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Systole is comprised of 

  1. Isovolumetric ventricular contraction

  2. Ventricular ejection

  3. Both A and B

  4. Isovolumetric ventricular relaxation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Systole is the phase of the contraction of the heart while diastole is the phase of the relaxation. During the ventricular systole the following events take place:

1. Isovolumetric ventricular contraction is the phase during which the pressure builds up in the ventricles but it is not enough to open the semi-lunar valves of the pulmonary artery and aorta.
2. The contraction of ventricles continue and reach up to the level where the blood pressure opens up the semi-lunar valves and the blood is ejected out into the pulmonary artery and aorta.
Hence, the correct answer is 'Both A and B'

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The first heart sound is produced when

  1. Intraventricular pressure decreases.

  2. Semilunar valve snaps shut.

  3. Bicuspid and tricuspid valve close quickly.

  4. Diastole begins.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The lub is the first heart sound, commonly termed S1, and is caused by turbulence caused by the closure of mitral and tricuspid valves at the start of systole. The second sound, dub or S2, is caused by the closure of aortic and pulmonary valves, marking the end of systole.

So, the correct answer is option C.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

One heartbeat in an average man lasts  

  1. 0.8 second

  2. 0.2 second

  3. 0.5 second

  4. 1 minute
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

One heartbeat in an average man lasts  0.8 second.

Heart rate, also known as pulse, is the number of times a person's heart beats per minute. A normal heart rate depends on the individual, age, body size, heart conditions, whether the person is sitting or moving, medication use and even air temperature. Even emotions can have an impact on heart rate. For example, getting excited or scared can increase the heart rate. But, most importantly, getting fitter lowers the heart rate, by making heart muscles work more efficiently.