Preload is the same as EDV (end-diastolic volume).
True
False
The Correct Answer is B
Correct answer: False
Preload refers to the degree of stretch of the ventricular myocardial fibers at the end of diastole, just before ventricular contraction. It is influenced by the volume of blood returning to the heart (venous return) and the compliance of the ventricular walls. End-diastolic volume (EDV) is the actual volume of blood present in the ventricle at the end of diastole. While preload is closely related to EDV, it is a functional measure of myocardial fiber stretch rather than a direct measurement of blood volume. Thus, preload describes the mechanical tension on the myocardium, whereas EDV quantifies the volume of blood in the chamber.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Correct answer: False
Afterload refers to the resistance the ventricles must overcome to eject blood into the aorta and pulmonary artery during systole. Vasoconstriction of blood vessels increases systemic vascular resistance, which raises afterload and makes it more difficult for the heart to pump blood effectively. Conversely, vasodilation decreases vascular resistance, lowering afterload and reducing cardiac workload. Anatomically, the aorta and systemic arteries are the primary sites where afterload is influenced, and physiologically, increased afterload can lead to higher ventricular pressure, reduced stroke volume, and increased myocardial oxygen demand.
Correct Answer is F
Explanation
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.
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