Ati nur211 mobility exam
Ati nur211 mobility exam ( 29 Questions)
Which of the following factors has a direct impact on stroke volume?
Blood pressure itself does not directly affect stroke volume. However, it can influence afterload, which in turn affects stroke volume. Blood pressure is the force exerted by circulating blood on the walls of blood vessels, and while it is related to cardiac function, it is not a direct determinant of stroke volume.
Preload directly affects stroke volume. Preload refers to the degree of stretch of the cardiac muscle fibers at the end of diastole, just before contraction. It is influenced by the volume of blood returning to the heart (venous return). According to the Frank-Starling law, an increase in preload leads to an increase in stroke volume due to the enhanced force of contraction.
Afterload also directly affects stroke volume. Afterload is the resistance the ventricles must overcome to eject blood during systole. It is influenced by factors such as arterial blood pressure and vascular resistance. An increase in afterload can decrease stroke volume because the heart has to work harder to pump blood against the higher resistance.
Heart rate does not directly affect stroke volume. Instead, heart rate and stroke volume together determine cardiac output (CO = HR × SV). While heart rate can influence the overall amount of blood pumped by the heart per minute, it does not directly change the volume of blood ejected with each beat.
Choice A Reason:
Blood pressure itself does not directly affect stroke volume. However, it can influence afterload, which in turn affects stroke volume. Blood pressure is the force exerted by circulating blood on the walls of blood vessels, and while it is related to cardiac function, it is not a direct determinant of stroke volume.
Choice B Reason:
Preload directly affects stroke volume. Preload refers to the degree of stretch of the cardiac muscle fibers at the end of diastole, just before contraction. It is influenced by the volume of blood returning to the heart (venous return). According to the Frank-Starling law, an increase in preload leads to an increase in stroke volume due to the enhanced force of contraction.
Choice C Reason:
Afterload also directly affects stroke volume. Afterload is the resistance the ventricles must overcome to eject blood during systole. It is influenced by factors such as arterial blood pressure and vascular resistance. An increase in afterload can decrease stroke volume because the heart has to work harder to pump blood against the higher resistance.
Choice D Reason:
Heart rate does not directly affect stroke volume. Instead, heart rate and stroke volume together determine cardiac output (CO = HR × SV). While heart rate can influence the overall amount of blood pumped by the heart per minute, it does not directly change the volume of blood ejected with each beat.