The Circulatory System - MPharm PHA115

Flashcards covering key terms and concepts related to the circulatory system discussed in the MPharm PHA115 course.

Refractoriness

The inability of more than enough stimulus to elicit an action potential after a previously elicited cardiac action potential.

Absolute Refractory Period (ARP)

The period during which no stimulus can elicit a new action potential.

Effective Refractory Period (ERP)

A period following the absolute refractory period where a stimulus can elicit some response, but not a full action potential.

Relative Refractory Period (RRP)

The period when a stronger than normal stimulus is required to elicit an action potential.

Automaticity

The ability of some cardiac cells to spontaneously initiate and fire action potentials.

Pacemaker Activity

The spontaneous electrical activity of cardiac cells, including the SA node and AV node.

SA Node

The heart's primary pacemaker, located in the right atrium.

Bundle of His

A specialized conducting tissue that transmits action potentials from the AV node to the ventricles.

Electrocardiogram (ECG/EKG)

A graphic representation of the electrical activity of the heart during depolarization and repolarization.

P Wave

The waveform on an ECG that represents atrial depolarization.

QRS Complex

The waveform on an ECG that represents ventricular depolarization.

T Wave

The waveform on an ECG that represents ventricular repolarization.

Intercalated Discs

Specialized structures in cardiac muscle cells that connect adjacent cells and facilitate communication.

Excitation-Contraction Coupling

The physiological process where an action potential triggers muscle contraction in cardiac cells.

Cardiac Cycle

The rhythmic pumping action of the heart, consisting of a systole and diastole phase.

Diastole

The phase of the cardiac cycle when the heart muscle relaxes and fills with blood.

Systole

The phase of the cardiac cycle when the heart muscle contracts and pumps blood out.