Conduction System of the Heart Quiz

Comprehensive Overview of Cardiac Physiology and ECG Interpretation

• Preload refers to the pressure in the ventricle at the end of diastole, while afterload is the resistance against which the heart must pump.
• Cardiac output is the amount of blood leaving the heart per minute, calculated by multiplying heart rate and stroke volume.
• Stroke volume is the amount of blood pumped out of one ventricle in a single beat, and Starling's Law states that the more the heart stretches, the more it will pump out.
• Peripheral vascular resistance is the opposition to blood flow offered by arterioles, determined by vasoconstriction and vasodilation.
• Inotropic refers to the force of contraction, while chronotropic affects the heart rate per unit of time, and dromotropic refers to the speed of impulse transmission between cells.
• Excitability is the force of contraction, automaticity refers to the heart generating its own electrical impulses, and conductivity refers to the transmission of electricity.
• The layers of the heart wall from innermost to outermost are endocardium, myocardium, pericardial cavity, epicardium, fibrous pericardium, and parietal pericardium.
• The sympathetic nervous system is responsible for the "fight or flight" response, increasing heart rate, contractile forces, and vasoconstriction, while the parasympathetic nervous system is responsible for the "rest and digest" response, decreasing heart rate and atrioventricular conduction rates.
• Vessels have three layers: tunica intima, tunica media, and tunica adventitia, while capillaries are only one cell thick.
• The cardiac cycle begins with atrial contraction, followed by ventricular contraction, and ends with ventricular relaxation.
• Polarization is the resting state of the heart, where the interior is electrically negative relative to the outside, while depolarization is the influx of sodium ions, and repolarization is the return of sodium ions to the outside and potassium to the inside.
• The blood flows from the inferior and superior vena cava to the right atrium, through the tricuspid valve to the right ventricle, through the pulmonary valve to the pulmonary artery, to the lungs for oxygenation, through the pulmonary vein to the left atrium, through the mitral valve to the left ventricle, through the aortic valve to the aorta, and to the body.
• The conduction system of the heart consists of the SA node, intranodal pathways, AV node, bundle of His, right and left bundle branches, Purkinje fibers, and individual myocytes. ECG interpretation involves analyzing heart rate, rhythm, P-wave, PR interval, and QRS complex. Heart rate can be counted using R to R intervals or counting QRS complexes in a six-second strip. Artifact is any electrocardiographic alteration