Question

Correct sequence of electrical impulse transmission in the human heart is
A) Purkinje fibres
B) Atrio ventricular node
C) Sino Atrial node
D) Bundle branches
E) Bundle of His

• A. C $\rightarrow$ B $\rightarrow$ E $\rightarrow$ D $\rightarrow$ A
• B. C $\rightarrow$ E $\rightarrow$ B $\rightarrow$ D $\rightarrow$ A
• C. C $\rightarrow$ D $\rightarrow$ B $\rightarrow$ E $\rightarrow$ A
• D. B $\rightarrow$ C $\rightarrow$ E $\rightarrow$ A $\rightarrow$ D

Hint:

Remember the "SA-AV-Bundle-Branches-Purkinje" pathway for cardiac conduction: \textbf{S}ino\textbf{A} (SA) node: Origin of impulse (pacemaker). \textbf{A}trio\textbf{V} (AV) node: Delay for atrial contraction. \textbf{B}undle of His: Connects atria to ventricles. \textbf{B}undle \textbf{B}ranches: Distributes impulse down septum. \textbf{P}urkinje Fibers: Rapid spread to ventricular muscle.

Answer 1

The Correct Option is A

Step 1: Understand the Cardiac Conduction System
The human heart has a specialized conduction system composed of cardiac muscle cells that generate and transmit electrical impulses, ensuring synchronized contraction of the atria and ventricles. Step 2: Trace the path of electrical impulse generation and transmission
The normal sequence of electrical impulse transmission in the heart is as follows:
1. Sinoatrial (SA) node (C): Often called the "pacemaker" of the heart, it spontaneously generates electrical impulses. The impulse originates here.
2. Atrioventricular (AV) node (B): The impulse from the SA node spreads through the atrial muscle and reaches the AV node. The AV node briefly delays the impulse, allowing the atria to fully contract and pump blood into the ventricles before ventricular contraction begins.
3. Bundle of His (E): From the AV node, the impulse travels down to the Bundle of His (also known as the atrioventricular bundle), which is located in the interventricular septum.
4. Bundle branches (D): The Bundle of His divides into left and right bundle branches, which extend down the interventricular septum towards the apex of the heart.
5. Purkinje fibers (A): The bundle branches then branch out into a network of Purkinje fibers, which rapidly distribute the impulse throughout the ventricular muscle, causing the ventricles to contract efficiently from the apex upwards. Step 3: Arrange the given components in the correct sequence
Based on the physiological pathway:
C (Sinoatrial node) $\rightarrow$ B (Atrioventricular node) $\rightarrow$ E (Bundle of His) $\rightarrow$ D (Bundle branches) $\rightarrow$ A (Purkinje fibres) Step 4: Compare with the given options
The correct sequence is C $\rightarrow$ B $\rightarrow$ E $\rightarrow$ D $\rightarrow$ A, which matches option (1).