What is the term for a heartbeat that is too fast?

A. The semilunar valves close, preventing backflow into the heart: During ventricular diastole, the ventricles relax and ventricular pressure falls below the pressure in the aorta and pulmonary trunk. This pressure gradient causes the aortic and pulmonary semilunar valves to close, preventing blood from flowing backward into the ventricles.

B. The electrical impulse initiates ventricular depolarization: Ventricular depolarization occurs during the onset of systole, not diastole. It is triggered by the action potential conducted through the bundle branches and Purkinje fibers, leading to contraction. Depolarization does not directly cause semilunar valve closure.

C. The atrioventricular valves close, preventing backflow into the atria: The atrioventricular (tricuspid and mitral) valves close at the beginning of ventricular systole when ventricular pressure exceeds atrial pressure. This prevents regurgitation into the atria and generates the first heart sound (S1), distinct from the semilunar valve closure occurring later in diastole.

D. The ventricles contract, forcing blood into the great arteries: Ventricular contraction occurs during systole when ventricular pressure rises above aortic and pulmonary pressures to open the semilunar valves. Closure of these valves happens during diastole when the ventricles relax, not during active ejection.

A. Small cardiac vein: The small cardiac vein runs along the right margin of the heart and drains blood from the right atrium and ventricle. It empties into the coronary sinus, facilitating venous return to the right atrium.

B. Coronary sinus: The coronary sinus is a large venous channel on the posterior aspect of the heart. It collects most cardiac venous blood and drains directly into the right atrium, completing coronary circulation.

C. Anterior cardiac vein: The anterior cardiac veins run along the anterior surface of the right ventricle. They bypass the coronary sinus, draining directly into the right atrium, and contribute to the venous return from the right ventricular myocardium.

D. Superior vena cava: The superior vena cava is a major systemic vein that returns deoxygenated blood from the upper body, including the head, neck, and upper limbs, directly into the right atrium of the heart.

E. Middle cardiac vein; The middle cardiac vein runs in the posterior interventricular sulcus, draining the posterior portion of both ventricles. It empties into the coronary sinus, ensuring efficient venous return from the heart’s posterior myocardium.

F. Great cardiac vein: The blood vessel highlighted in the image is the great cardiac vein located on the anterior surface of the heart. The great cardiac vein begins at the apex of the heart and eventually curves around the left side of the heart (within the coronary sulcus) to empty into the coronary sinus on the posterior side. It is the principal vein of the anterior heart.