A wave in JVP is due to

The atrial pressure changes are transmitted to the great veins, producing three characteristic waves in the record of jugular pressure. The A wave is due to atrial systole. C wave due to ventricular systole. It is caused paly by paial backflow of blood into atria during onset of ventricular contraction but mainly due to bulging of av valves backwards towards atria due to increasing pressure in ventricle. V wave is occurs towards end of ventricular contraction as a result of Slow flow of blood into atria frim the veins when the av valves are closed during ventricular contraction. Ref: Ganong's Review of medical physiology 25th edition. Page: 542, Gyton textbook of medical physiology, page 106