Answer to Question 1
ANS: D
A whooshing sound at the fifth intercostal space is a murmur; a prolapsed valve allows regurgitation that is heard as a whooshing sound. The systolic phase begins with ventricular filling and closing of the aortic valve, which is heard as the first heart sound, S1. The third heart sound, S3, is heard with heart failure.
Answer to Question 2
ANS: A
The SA node initiates electrical conduction through the atria. The AV node conducts down through the bundle of HIS and the Purkinje network to cause ventricular contraction.