Fill in the blanks: The first heart sound is called______and it is caused by the closing of the_____valves. It occurs at the beginning of the_____phase of the cardiac cycle. The second heart sound is called_____and it is caused by the closing of the______ valves. It occurs at the beginning of the_____phase of the cardiac cycle.

Video transcript

Hi everyone. Let's take a look at this practice problem together. Which of the following statements about isovolumetric relaxation is false. The answer options are a, the volume of blood in this state remains constant. B this phase occurs after the closure of semi lunar valves. C the pressure within the ventricles increases during this phase and D this process occurs before the opening of the A V valves. So what is isovolumetric relaxation? Recall that it is the time interval between when the aortic valve closes and ventricular filling begins. Now, two things are important to note during this phase. The first is that the ventricles are relaxed, they are not contracting. And the second is that there is no change in ventricular blood volume. The name isovolumetric relaxation literally means relaxation with same volume. So which of the answer options is false. Option. A, the volume of blood remains constant. This is a true statement. Isovolumetric means same volume. So we can eliminate option A option B recall that the semi lunar valves are the pulmonary and aortic valves. Isovolumetric relaxation starts after the aortic valve is closed. So we can eliminate option B as well. Option D the process occurs before a V valve opening. Remember when A V valves open, the ventricles will fill with blood from the atrium. An isometric relaxation occurs between aortic valve closure and ventricular feeling. So this statement is also true and we can eliminate option D. That means that the correct answer is option C during iso excuse me, during isovolumetric relaxation, the ventricular pressure decreases, it does not increase and that ventricular pressure decrease will eventually lead to a V valve opening. So the correct answer is option C the pressure within the ventricles increases during this phase. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.