Question

Purkinje fibers are present in
A. Ventricles
B. Auricles
C. Striated muscle fiber
D. Throughout the heart

Answer 1

In the inner ventricular walls of the heart, just below the endocardium in a space called the subendocardium, the Purkinje fibres are found in the Purkinje tissue or subendocardial branches. The Purkinje fibres are specialised conducting fibres made up of electrically excitable cells that are larger than cardiomyocytes with less myofibrils and more mitochondria and that conduct cardiac action potentials faster and more effectively than any other heart cells.

Complete step by step answer:
In the inner ventricular walls of the heart, just under the endocardium, in a space called the subendocardium, the Purkinje fibres are found. These fibres consist of advanced cardiomyocytes that are capable of carrying out the potential for cardiac action. Purkinje fibres enable synchronised contractions of its ventricles to be produced by the heart's conduction system, and are therefore important for maintaining a steady heart rhythm.

Additional information: In the subendocardium, the Purkinje fibres are located. They are bigger than cells of the cardiac muscle but have less myofibrils, plenty of mitochondria and glycogen, and no T-tubules.
Hence, option A: Ventricles is the correct answer.

Note: Purkinje fibres are part of the heart's specialised conduction network that ensures that the wave of excitation travels to the ventricular muscle mass easily and almost synchronously. These cells are located on the subendocardial surface of the ventricular walls and are capable of transmitting the potential for cardiac activity quickly from the atrioventricular bundle to the ventricular myocardium.