Circulatory System and Electrical Activity of the Heart

This set of flashcards covers key vocabulary and concepts related to the circulatory system and the electrical activity of the heart, essential for understanding cardiac physiology and preparing for exams.

SA node

Sinoatrial node, the primary pacemaker of the heart that initiates electrical signaling.

AV node

Atrioventricular node, responsible for slowing down electrical conduction to allow atrial contraction before ventricular contraction.

Depolarization

The process by which the membrane potential of a cell becomes more positive, leading to the contraction of the heart muscle.

ECG (Electrocardiogram)

A test that records the electrical activity of the heart over a period of time.

QRS complex

The part of the ECG that represents ventricular depolarization.

PR interval

The period from the start of atrial depolarization to the start of ventricular depolarization, indicative of conduction through the AV node.

Bundle branches

Part of the heart's conduction system that sends impulses to the ventricles.

Purkinje fibers

Fibers that distribute the electrical impulse throughout the ventricles and lead to their contraction.

Cardiac output (CO)

The amount of blood pumped by the heart per minute.

Stroke volume (SV)

The volume of blood ejected from the ventricle with each heartbeat.

Inotropic agents

Substances that affect the force of heart contractions.

Frank-Starling law

The principle that the heart will pump out as much blood as is returned to it, related to muscle stretch.

Systole

The phase of the heartbeat when the heart muscle contracts and pumps blood.

Diastole

The phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood.

H2O

Chemical formula for water, referred to in the context of blood plasma composition.

Baroreceptor reflex

A physiological mechanism that helps regulate blood pressure via changes in heart rate and vascular resistance.

Vasodilation

The widening of blood vessels, which decreases blood pressure.

Vasoconstriction

The narrowing of blood vessels, which increases blood pressure.

Mean Arterial Pressure (MAP)

The average arterial pressure during one cardiac cycle, crucial for assessing blood flow.

Plasma Proteins

Proteins found in blood plasma, such as albumin, globulins, and fibrinogen, that play key roles in immune response and blood clotting.

Electrolytes

Minerals in the body fluids that have an electric charge and are essential for various bodily functions, including heart activity.

Conducting system of the heart

The network that generates and conducts electrical impulses in the heart to coordinate contractions.

Resistive factors

Factors influencing the resistance to blood flow, including vessel diameter and blood viscosity.

Atrial and ventricular contraction

The coordinated contraction of the heart's chambers, enabled by the conduction system.