QuestionSBA
QuestionChoice
This is incorrect as isovolumetric contraction must occur before the aortic valve opens. If the aortic valve opened first, the pressure would still be higher in the aorta than the ventricle and so blood would pass back down from the aorta into the left ventricle. Instead, isovolumetric contraction occurs first to raise the left ventricular pressure above that of the aorta to open the aortic valve.
10026253
d
Bicuspid valve closure, aortic valve opening, isovolumetric contraction, ventricular ejection
QuestionChoice
This is the correct order of events. Initially, the left ventricle begins to contract, raising its pressure above that of the left atrium so that the bicuspid valve closes. There is then the period of isovolumetric contraction whereby the ventricular pressure rises rapidly. Once this exceeds the pressure in the aorta, the aortic valve opens and ventricular ejection occurs.
10026250
a
Bicuspid valve closure, isovolumetric contraction, aortic valve opening, ventricular ejection
QuestionChoice
This is incorrect as bicuspid valve closure must occur before isovolumetric contraction. Isovolumetric contraction is the period when both bicuspid and aortic valves are closed, such that the ventricle contracts, raising the pressure very rapidly. This allows the ventricular pressure to increase above that of the aorta so that the aortic valve can open. If isovolumetric contraction occurred before bicuspid valve closure, blood would be forced back up into the left atrium.
10026252
c
Isovolumetric contraction, bicuspid valve closure, aortic valve opening, ventricular ejection
QuestionChoice
Although the order of events is correct, the question refers specifically to the left ventricle and so it is the bicuspid valve that initially closes, not the tricuspid valve.
10026251
b
Tricuspid valve closure, isovolumetric contraction, aortic valve opening, ventricular ejection
QuestionChoice
This answer is incorrect for two reasons. Firstly, the question refers specifically to the left ventricle and so it is the bicuspid valve that initially closes, not the tricuspid valve. Secondly, it is isovolumetric contraction, not relaxation, that occurs in systole to raise the ventricular pressure.
10026254
e
Tricuspid valve closure, isovolumetric relaxation, aortic valve opening, ventricular ejection
Concept
Chapter
2693
4231
Blood flow through the heart
Topic
159
Cardiovascular physiology
17648
Which of the following is the correct sequence of events in left ventricular systole?
a