JVP waves:
Upward waves (due to increase right artial pressure)
1. a wave: atrial contraction
2. c wave: bulging of the tricuspid valve into the right atrium
3. v wave: atrial filling against a closed tricuspid valve
Downward waves (due to decrease right artial pressure)
1. x wave: atrial relaxation
2. y wave: atrial emptying
