Say whether the valves are open or shut at each moment…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Say whether the valves are open or shut at each moment.
- Joint diastole: the valves between the atria and the ventricles.
- Ventricular systole: the semilunar valves.
- Ventricular systole: the valves between the atria and the ventricles.
- Ventricular diastole, just after it starts: the semilunar valves.
- Which heart sound is made when the valves in (d) shut?
Need a reminder? The key ideaShow
The cardiac cycle lasts about s: atrial systole s, ventricular systole s, joint diastole s. The valves between the atria and the ventricles are shut in the ventricular systole, and the semilunar valves are open only then. Cardiac output equals stroke volume times heart rate: in a minute.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Open. Blood flows from the atria into the relaxed ventricles.
Step 2. (b) Open. The pressure of the ventricles is higher than that of the arteries.
Step 3. (c) Shut. The ventricular pressure is higher than the atrial pressure.
Step 4. (d) Shut. The ventricles relax, and the blood in the arteries would flow back.
Step 5. (e) The second sound, dub.
Answer: (a) open; (b) open; (c) shut; (d) shut; (e) dub.
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