Question

Which of the following describes the effect of end-diastolic volume on stroke volume?

a) An increase in end-diastolic volume stretches ventricular muscle cells to lengths closer to optimum, increasing the strength of contraction and thereby increasing stroke volume.
b) A decrease in end-diastolic volume allows cardiac muscle to relax, conserving energy for the next contraction, thereby increasing stroke volume of that next contraction.
c) A decrease in end-diastolic volume creates a vacuum drawing more blood into the ventricle increasing stroke volume.
d) A decrease in end-diastolic volume allows ventricular muscle cells to relax more during diastole, allowing more blood to return to the heart increasing stroke volume.
e) An increase in end-diastolic volume stretches ventricular muscle cells to lengths greater than optimum, decreasing the strength of contraction and thereby decreasing stroke volume.

Answer 1

a) is the correct option

Step-by-step explanation:

• The heart consists of four chambers: two atria and two ventricles and also contain valves that open and close in sequence so that blood flows in one direction through the atria and ventricles
• The veins carry oxygen-poor blood into the right atrium, which connects to the right ventricle; from here, the heart pumps blood into the lungs for oxygenation
• The newly oxygenated blood enters the left atrium and flows into the left ventricle, which contracts, forcing blood up through the aorta
• The aorta is the largest artery in the body, and it supplies the entire body with oxygen-rich blood
• Diastole occurs when the heart muscle relaxes, and the chambers fill with blood, blood pressure decreases during diastole
• Systole occurs when the ventricles contract, pushing blood out of the right ventricle into the lungs and out of the left ventricle to the rest of the body, blood pressure increases during systole
• End-diastolic volume is the amount of blood that is in the ventricles before the heart contracts
• Doctors use both end-diastolic volume and end-systolic volume to calculate stroke volume
• End-systolic volume is the amount of blood remaining in the ventricle at the end of systole, after the heart has contracted
• Stroke volume is the quantity of blood that the heart pumps out of the left ventricle with each beat
• The formula for stroke volume can be written as: Stroke volume = end-diastolic volume – end-systolic volume