Name:___________________________ Pd:_____
Cardiac Cycle Web Quest
1. Go to http://bcs.whfreeman.com/thelifewire/content/chp49/49020.html First, read the introduction
then answer the following questions.
a. What is the cardiac cycle? What constitutes one round of the cardiac cycle?
b. What happens to cardiac muscle during systole?
c. What happens to cardiac muscle during diastole?
2. Now click on the tab that says “Animation” and watch the steps of the cardiac cycle. Watch the
narrated animation then read the notes that pop up on the screen after the narration has ended to
answer the following questions. You may have to watch this animation and/or rewind it several times.
a. What event/events in the cardiac cycle produce the lub dub sound that most people
associate with the heart (which valves make the lub and which make the dub)?
b. ***The answer to this pops up on the screen after the narration has ended! List 3 events that
occur during diastole (relaxation of the ventricles). These will not all appear at the same time,
some are shown at the beginning of the clip and some are at the end.
i.
ii.
iii.
c. ***The answer to this pops up on the screen after the narration has ended! List 3 events that
occur during systole (contraction of the ventricles). These do appear at the same time.
i.
ii.
iii.
3. Click the tab that says “Conclusion” and read the information on the page. When you have finished
see how you do on the quiz. Record the correct answers under each question here.
a. During the systole phase of the cardiac cycle, high blood pressure in the ventricles forces the
____________________________________________________.
b. When is the ventricular blood volume higher? ______________________________________
c. In the cardiac when do the atrioventricular valves close?
_______________________________________________________________
4. Go to http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter22/animation__
the_cardiac_cycle__quiz_1_.html and watch the cardiac cycle video to help this idea make sense.
5. In the informative paragraph circle the term that best describes the preceding statement, systole or
diastole:
The average heart beats 75 times per minute. That means the events of the cardiac cycle occur
in approximately 0.8 seconds! During the 0.8 seconds, atrial contraction occupies the first 0.1
second, which is followed by atrial relaxation and ventricular contraction (systole or diastole) for the
next 0.30 second period. The remaining 0.40 seconds is the ventricular relaxation period (systole or
diastole). When the heart beats at a more rapid pace than normal, the last period during ventricular
relaxation becomes shorter.
***Fun Fact: If the human heart beats about 75 times per minute that means the human heart beats
4,500 times in one hour, 108,000 times a day, 756,000 times per week, and 39,312,000 times per year!
6. This diagram shows what is happening in the heart during each step of the cardiac cycle. We will
discuss this diagram and the events of each phase of the cardiac cycle in class. Review them here
so you are ready to go when we get to this in lecture!
- Mid-to-late diastole— blood flows from the atria into the ventricles, about 70% of the blood that flows
into the ventricles happens while the AV valves are open (both chambers are relaxed, AV valves open)
then the atria contract to squeeze remaining 30% of the blood into the ventricles
- Ventricular systole— blood pressure builds before ventricles contract, when ventricles begin to
contract pressure gets high enough opening the semilunar valves allowing blood to be pushed out to the
lungs and body
- Early diastole— atria finish refilling, when the pressure in the atria exceeds the pressure in the
ventricles the AV valves will open allowing blood to fill the ventricles  the cycle begins again