Conduction in Heart

Q.

Assertion[A]: Atria and ventricles do not contract at the same time.

Reason[R]: This time delay allows proper filling of all the 4 chambers of the heart and results in an efficient pumping of blood.

1. A is true and R is false.

2. R is true and A is false.

3. Both A and R are true and R is correct explanation of A.

4. Both A and r are true but R is not correct explanation for A.

Q.

The heart’s natural pacemaker is termed as the:

1. atrioventricular node

2. bundle of His

3. left and right bundle branches

4. sinoatrial node

Q. What happens when the pacemaker is non functional?

1. Only ventricles contract rhythmically.
2. Cardiac muscles will contract in a coordinated manner.
3. Only the auricles will contract rhythmically
4. The cardiac muscles do not contract in a coordinated manner rhythmically.

Q. Frog's heart, when taken out of the body, continues to beat for some time.
Select the best option from the following statements.
(a) Frog is a poikilotherm
(b) Frog does not have any coronary circulation
(c) Heart is "myogenic" in nature
(d) Heart is auto-excitable

1. Only (d)
2. (a) and (b)
3. (c) and (d)
4. Only (c)

Q.

Which of the following is not true about the heart’s conduction system?

1. The SA node generates action potentials higher than all the other parts of the conducting system.

2. The SA node generates specifically 70 action potentials per minute.

3. If all the other portions of the conducting system other than the SA node, produce action potentials at a much slower rate, it would maintain our heart rate.

4. Other muscles receive impulses through the neurons from the brain, but heart produces its own potential

Q.

Identify the labelled parts of heart’s conduction system as depicted in the image.

1. (i)Purkinjefibres, (ii)Bundle of His, (iii) SA node, (iv) AV node

2. (i)SA node, (ii) AV node, (iii) Bundle of His, (iv) Purkinje fibres

3. (i)Bundle of His, (ii) Purkinjefibres, (iii) AV node, (iv) SA node

4. (i)SA node, (ii) Purkinjefibres, (iii) AV node, (iv) Bundle of His

Q.

Find out the wrong statement:

1. Tricuspid valve is located between right atrium and right ventricle

2. SA node is called the pacemaker of the heart

3. By counting the number of QRS complexes that occur in a given time period, one can determine the heart beat rate of an individual

4. The P wave represents the depolarization of the atria while QRS complex represents the repolarization of the ventricles

Q. Assertion: SA node induces excitatory impulses in the heart.
Reason: S.A. node is self-excitatory.

1. Both assertion and reason are false.
2. Both assertion and reason, are true and the reason is the correct explanation of assertion.
3. Both assertion and reason, are true but the reason is not the correct explanation of the assertion.
4. The assertion is true but the reason is false

Q.

Which of the following statement is/are correct?

A marathon runner is likely to show
1. Reduced heart rate
2. Enlarged heart
3. Larger stroke volume
4. Decreased arterial blood pressure

1. All of the above

2. 1, 2 and 3

3. 1 and 2

4. 1 alone

Q.

Identify the labelled parts of heart’s conduction system as depicted in the image.

1. (i)SA node, (ii) Purkinjefibres, (iii) AV node, (iv) Bundle of His

2. (i)Bundle of His, (ii) Purkinjefibres, (iii) AV node, (iv) SA node

3. (i)Purkinjefibres, (ii)Bundle of His, (iii) SA node, (iv) AV node

4. (i)SA node, (ii) AV node, (iii) Bundle of His, (iv) Purkinje fibres