Anatomy of Heart/Conduction System

Pulmonary Circulation

The blood vessels carrying oxygen-poor blood to the lungs to become oxygenated; also vessels that return the oxygen-rich blood to the heart

Systemic Circulation

Blood vessels that supply blood to all other areas of the body with the exception of the myocardium

Coronary Circulation

Referring to the blood vessels that supply the myocardium with nutrients and oxygen; and those that remove wastes:

• Aorta branches into right and left coronary arteries (get first dibs on oxygen-rich blood)

• Cardiac veins drain blood from the walls of the heart into the coronary sinus, empties into right atrium

Ischemia 

Reduced blood flow to the heart, resulting in inadequate oxygen being delivered

Angina Pectoris

The pain that results from ischemia in the chest

Myocardial Infarction (MI)

Heart attack; dead/dysfunctional muscle tissue of the heart that cannot be regrown. May need to be fixed via coronary bypass surgery, with angina as a common side effect

Atherosclerosis

Fatty plaque build up in the arteries; results in increased afterload

Lub

Closing of the atrioventricular (AV) valves upon ventricular systole

Dub

Closing of the semilunar (SL) valves upon ventricular diastole

Sinoatrial (SA) Node

Pacemaker for the heart; found in the wall of right atrium, spontaneously depolarized in response to Na⁺ (generates action potential every 0.8/secs). Establishes baseline for heart rate

Intercalated Discs

Joins the myocardial cells of the heart; uses gap junction to reach each cell for contraction

Pathway of Conduction

SA node — AV node — AV Bundle — Purkinje fibers — cardiac cells

Calcium Purpose

Binds to tropinin; used for myocardial muscle contraction

Cardiac Plateau

Maintained depolarization, voltage gated Ca⁺⁺ channels open and slow to close; stimulates release of calcium from the SR

Long Refractory Period

Tetany is unable to happen in order to maintain pumping action; myocardium returns to rest before contraction is able to continue