Anatomy & Physiology - Autorhythmic Cells and Cardiac Conduction System

Vocabulary flashcards for Anatomy & Physiology lecture on Autorhythmic Cells and Cardiac Conduction System.

Autorhythmic Cells (Pacemaker)

Electrically self-excitable cells that spontaneously and rhythmically generate and conduct action potentials, facilitating coordinated contraction and relaxation of cardiac chambers.

Contractile Cardiac Myocytes

Cardiac muscle cells with many myofibrils that are electrically excitable and responsible for the contraction of cardiac chambers, required for propulsion of blood.

Voltage-gated Na+ ‘funny’ channels

Special voltage-gated ion channels in SA node pacemaker cells that facilitate spontaneous depolarization to threshold.

T-type Voltage-gated Ca2+ channels

Voltage-gated calcium channels that open at threshold in pacemaker cells allowing influx of Calcium (Ca2+), which produces the rising phase of the action potential and reverses the membrane potential

Sinoatrial (SA) Node

Collection of autorhythmic cells located in the right atrium that spontaneously generate an action potential approximately every 0.6 seconds, setting the intrinsic rate of the heart.

Cardiac Conduction System

Groups of autorhythmic cells distributed throughout the heart that dictate how the wave of the electrical signal proceeds through the cardiac chambers, ensuring coordinated contraction and relaxation.

Internodal Pathway

Pathway that connects the SA node to AV node

Bachmann’s Bundle

Fast-tracks depolarizing current from the SA node to the left atrium to ensure both atria depolarize and contract at approximately the same time.

Atrioventricular (AV) Node

Delays conduction of the electrical signal, allowing the atria to complete contraction before the ventricles contract, facilitating optimal ventricular filling.

Dense Fibrous Connective Tissue

Electrical insulator between atria and ventricles

AV bundle of His

The route of excitation/depolarization is restricted to this after the signal passes through the cardiac skeleton

Purkinje Fibers

Transmit the wave of excitation in the ventricles from the apex back towards the atria; largest diameter of the myocardial cells for faster conduction and rapid activation of entire endocardial surface of ventricles