Finish the flow chart below to show the route taken by blood through the heart: vena cava $\rightarrow$ right atrium $\rightarrow$ valve P $\rightarrow$ [ ] $\rightarrow$ valve S $\rightarrow$ pulmonary artery $\rightarrow$ lungs $\rightarrow$ [ ] $\rightarrow$ left atrium $\rightarrow$ valve Q $\rightarrow$ left ventricle $\rightarrow$ valve R $\rightarrow$ aorta.
Explain how valves P and Q keep blood flowing in one direction through the heart.
In the table below, pair each event in the cardiac cycle with the correct number $1$ to $7$ on Fig. 3.2. Put just one number in every box. You may use any number once, more than once or not at all. The first answer is already done for you.
Explain the functions of the sinoatrial node (SAN), atrioventricular node (AVN) and the Purkyne tissue during one heart beat.