Conduction in Heart

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

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. What happens when the pacemaker is non functional?

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

Q.

The conduction mechanism consists of three stages. Which of the following is the correct order of events during this process?

1. atrial depolarization → ventricular depolarization → atrial and ventricular repolarization

2. ventricular repolarization → atrial depolarization → atrial and ventricular repolarization

3. atrial and ventricular repolarization → ventricular depolarization → atrial depolarization

4. ventricular repolarization→ atrial depolarization→ atrial and ventricular depolarization

Q.

Find out the wrong statement:

1. SA node is called the pacemaker of the heart

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

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. 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 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.

Sino-atrial node is called the pacemaker of our heart. Why?