Question

The cardiac impulse is initiated and conducted further upto ventricle. The correct sequence of conduction of impulse is
A. S A Node A V Node Purkinje fibres A V Bundle
B. S A Node Purkinje fibres A V Node A V Bundle
C. S A Node A V Node A V Bundle Purkinje fibres
D. S A Node Purkinje fibres A V Bundle A V Node

Answer 1

Hint: The continuous period of contraction of the heart muscle followed by relaxation allows blood to be pumped all over the body. Various factors like exercise, temperature, and endocrine system hormones may affect cardiac conduction.

Complete Answer:
Impulse generation is the first step in cardiac conduction. Cardiac conduction is the rate at which electric impulses are conducted by the heart. These impulses make the heart contract and then calming.

Now, let us find the solution from the option.
-The Sinoatrial (SA) node also known as the heart's pacemaker contracts, creating nerve impulses that travel across the heart wall. This creates contracting of both atrias. The SA node lies in the upper right atrium wall.
-The atrioventricular (AV) node situated close to the bottom of the right atrium on the right side of the partition which divides the atria. Upon hitting the AV node, the impulses from the SA node are interrupted by about a tenth of a second. This delay helps atria to contract and drain their contents into the ventricles before contracting with the ventricle.
-The impulses are then sent down to the packet of atrioventriculares. This collection of fibres branches off into two bundles, and the impulses are passed to the left and right ventricles down the centre of the heart.
-The atrioventricular bundles at the base of the heart continue to further separate into Purkinje fibres. When the impulses reach certain fibres they cause contraction of the muscle fibres in the ventricles. The right ventricle transmits blood from the pulmonary artery to the lungs. The left ventricle is pumping blood into the aorta.

Thus, the correct option is (C) S A Node A V Node A V Bundle Purkinje fibres.

Note: Heart conduction is the driving factor behind cardiac cycle. This cycle is the sequence of occurrences when the heart beats. The atria and ventricles are relaxed during the diastole phase of the cardiac cycle and blood goes into the atria and the ventricles.