Download 1 2 Heart, circulation and cardiac cycle

3.3.4 Mass Transport in Animals
The Mammalian Heart and Circulatory System
Single Circulation or Double Circulation?
For Example: Fish
For Example: Mammals
The Heart
1. What is the function of the heart?
2. How does the structure of cardiac muscle enable the heart to carry out its function?
3. Label the diagram of the heart. Draw arrows to show the direction of blood flow.
3.3.4 Mass Transport in Animals
The Circulatory System
4. Label the missing arteries and veins.
CLUES:
- Arteries take blood away from the heart
- Veins take blood towards the heart
- Hepatic – concerning the liver
- Renal – concerning the kidneys
- Pulmonary – concerning the lungs
3.3.4 Mass Transport in Animals
Questions on the Structure and Function of the Circulatory system
4. Which heart chamber has the thickest muscular wall? Explain why this feature is
important.
5. What is the purpose of the valves in the heart, aorta and pulmonary artery?
6. What is meant by the term ‘double circulation’?
7. Which side of the heart contains oxygenated blood?
8. List the structures through which blood travels from the lungs, around the body and
back to the lungs.
9. Below is a diagram showing an external view of a mammalian heart.
a) Suggest the function of the coronary artery.
b) From which blood vessel does the coronary artery originate?
3.3.4 Mass Transport in Animals
The Cardiac Cycle
3.3.4 Mass Transport in Animals
Questions on the Cardiac Cycle
10. Define the following terms:
a. Stroke volume
b. Heart rate
c. Cardiac output
11. Starting with atrial systole, describe when the semilunar and atrioventricular valves
open and close.
12. What causes the atrioventricular valves to:
a) Open?
b) Close?
13. What causes the semilunar valves to:
a) Open?
b) Close?
3.3.4 Mass Transport in Animals
14. Examine the diagram below and answer the questions that follow.
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?
3.3.4 Mass Transport in Animals
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.
3.3.4 Mass Transport in Animals
Past Paper Question (2005)
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
(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.
Stroke volume = .......................................... cm3
(2 marks)