the heart Flashcards
1
Q
describe what is meant by a double circulatory system
A
the right ventricle pumps blood to the lungs
the left ventricle pumps blood around the body
2
Q
explain why veins have valves but arteries don’t
A
veins have valves to prevent the back flow of blood
because blood in veins is at a lower pressure than in the arteries
3
Q
two structural differences between a vein and an artery
A
- vein wall has a thinner layer of muscle tissue
- wall of vein has a thinner layer elastic tissue
