1. Unit 4
The circulatory and excretory systems
Biology and Geology 3

2. What do we know? Suggested questions and discussion starters:
How does is this photo related to the unit: ‘The circulatory and excretory systems’?
How do you think the two systems are linked to one another?
What is blood made up of?
How is blood and the lymphatic system connected?

7. The functions of blood
What are the functions of the three components of blood shown in the illustration?
Overall, what are the main functions of blood in the body?

8. The blood vessels
What are the main differences between arteries and veins?
What is the structure and function of capillaries?

12. The heart
Are the two halves of the heart linked together? Why or why not?
Are the atrium and ventricle connected? How?

16. Circulation through the blood vessels
What is a sphincter?
Does blood flow faster or slower through the capillaries? Why?

17. Circulation through the blood vessels
In which order is blood is pumped through the following vessels: arteries, atria, ventricles and veins?
How do the three illustrations show how blood is pumped through the venules and veins?

19. Blood circulation: a double circuit
Why is blood circulation described as a double circuit?
‘Circulation is closed and complete.’ What does this mean?