Download 1 2 Heart structure and cardiac cycle

AS The Heart and Heart Disease
The Heart – Structure and Function
1. What is the function of the heart?
2. How does the structure of cardiac muscle tissue enable the heart to perform its
function?
3. Label the diagram of the heart:
4. Draw arrows onto your diagram to indicate the direction in which blood flows.
5. Which chamber has the thickest muscular wall? Explain why it is important.
6. What is the purpose of the valves?
7. What is meant by the term ‘double circulation’?
AS The Heart and Heart Disease
8. Which side of the heart contains oxygenated blood?
9. Annotate the diagrams to show the events that take place during the cardiac cycle.
AS The Heart and Heart Disease
10. Define the following terms:
a. Stroke volume
b. Heart rate
c. Cardiac output
11. List the structures through which blood travels from the lungs, around the body and
back to the lungs.
12. Examine the diagram below and answer the questions that follow.
AS The Heart and Heart Disease
a. Use the graph to calculate how many complete cardiac cycles (heartbeats) there are per
minute.
b. What causes the pressure to change in the ventricles at around 0.17seconds?
c. At what time in the cardiac cycle would the semi-lunar valves open? What would cause
them to open?
d. At what times during the cardiac cycle would the atrioventricular valves be open?
Explain your answer.
e. At what time in the cardiac cycle would the semi-lunar valves close?
f. Contraction of the ventricles takes approximately 0.3 seconds. If the same rate of
heartbeat shown in the graph was maintained throughout a 12 hour period, for how
many hours would the ventricular muscle be contracting? Show your working.
AS The Heart and Heart Disease
The Cardiac Cycle
Application June 2005
1) The graph shows the changes in pressure which take place in the aorta of a mouse during
several heartbeats.
(a) Which chamber of the heart produces the increase in pressure recorded in the aorta?
_________________________________________________________________________________
(1 mark)
(b) The pressure of blood in the aorta decreases during each heartbeat but does not fall below 10 kPa. Explain
what causes the pressure of blood to
(i) decrease during each heartbeat;
___________________________________________________________________________________________
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(1 mark)
(ii) stay above 10 kPa.
___________________________________________________________________________________________
_______________________________________________________________________
_________________________________________________________________________________ (2 marks)
(c) The heart rate of a mouse is much higher than the heart rate of a human. Use the graph
to calculate the heart rate of the mouse. Show your working.
Heart rate = .......................................... beats per minute
(2 marks)
(d) The cardiac output is the volume of blood pumped by a heart in one minute. The stroke volume is the volume
of blood pumped by a heart in a single heartbeat.
cardiac output = stroke volume xheart rate
The cardiac output for a mouse with a heart rate of 550 beats per minute is 16.6cm3 per
minute. Calculate the stroke volume for this mouse. Show your working.
AS The Heart and Heart Disease
Stroke volume = .......................................... cm3
(2 marks)