Download The general idea with this activity is for the students to work through

Cardiac Cycle
Tutor’s notes
The general idea with this activity is for the students to work through the blood pressure
changes that occur during the cardiac cycle so that they gain a better understanding of the
graph of the cardiac cycle.
It is a good idea to begin this activity by reminding the students of the structure of the heart.
Make available any diagrams, wall charts, models, etc.
A video clip of the heart beating would also be very useful. This can be cross referenced to Fig.
1 on Page 1 of the activity.
A good interactive web site is:
http://medlib.med.utah.edu/kw/pharm/hyper_heart1.html
Hand out the packs of materials.
Arrange the group into pairs.
Task 1
The students work in pairs without any reference material (wall charts, text books etc) to hand.
They arrange the cards in Envelope 1 to show the pathway taken by blood as it travels through
the heart. Please check their answers. They may have text books to check their answers.
Arrange the students into groups of 3 or 4.
Make sure that they have the three acetate sheets and the graph paper. Please note that the
cardiac cycles on the acetate sheets are not exactly the same as those in text books. But they
are fairly close to those in the OCR endorsed text books.
It is not easy to tell from the pressure changes when the atria and ventricles contract, so the
graph with the phases overlayed may be helpful. See in this pack.
Task 2
Answers
1
-0.1 kPa (it may be necessary to explain why the pressure is less than 0)
0.07 s
2
1.4 kPa
0.2 s
3
0.1 s to 0.25s
4
left ventricle
Page 1 of 3
Tutor’s notes
Cardiac Cycle
Task 3
5
0 kPa
0.24 / 0.25 s
6
16.1 kPa
0.44 s
7
0.24 s to 0.55 s
8
aorta
Task 4
9
10.1 kPa
0.3 s
10
15.85 / 15.9 kPa
0.44 s
11
main arteries (not pulmonary artery) / organs (not the lungs)
Task 5
12
0.25 s
13
atrio-ventricular valve / bicuspid valve, closes
14
0.32 s
15
semi-lunar valve / aortic valve, opens
16
0.55 s
17
semi-lunar valve / aortic valve, closes
18
0.63 s
19
blood flows from left atrium to left ventricle
The questions underneath Figure 2 are not numbered.
2
80 (60 seconds divided by 0.75)
valve
atrio-ventricular valve
semi-lunar valves
opens
closes
4
1
2
3
Page 2 of 3
Cardiac Cycle
Tutor’s notes
Answers to second card sort
The atria and ventricles are relaxed and empty.
This phase is called diastole.
Blood at low pressure enters the atria.
As they fill up with blood the pressure in the atria increases.
When the pressure exceeds that in the ventricles blood flows through the atrioventricular valves
into the ventricles.
The atria contract.
This contraction empties the atria.
The ventricles contract almost immediately.
This phase is called systole.
This increases the pressure in them above that in the pulmonary arteries and aorta.
Blood flows into the pulmonary arteries and the aorta.
The elastic walls of the aorta stretch to accommodate the blood
The ventricles and atria relax.
The pressure in the ventricles is now less than in the pulmonary arteries and the aorta.
The backflow of blood is prevented by the semilunar valves and contraction of the aorta walls.
The cards for SAN, AVN and Purkinje fibres can be inserted in the sequence as follows:
SAN before the atria contract
AVN and Purkinje fibres before the ventricles contract
The students can write on the back of the cards.
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