(a)[2]
Explain why the wall of the left ventricle is thicker than that of the left atrium.
(b)[3]
Explain how the labelled structures in Fig. 5.1 make sure that blood moves in the correct direction.
(c)[4]
During one cardiac cycle, blood is pumped out of the heart into the pulmonary and systemic circulations. Explain how contraction of the four chambers of the heart is coordinated and controlled so that blood is pumped simultaneously into both the pulmonary and systemic circulations.