This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'A wave in JVP is due to- \nSelect and explain. \nA. Atrial contraction, B. Ventricular filling, C. Atrial filling, D. Bulging of tricuspid valve in right atrium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., Atrial contraction JUGULAR VENOUS PULSEa waveIt is the positive presystolic wave produced by right atrial contraction.x descenta wave is followed by the negative systolic wave the x \' descent. The x descent is produced due to atrial relaxation. The atrial relaxation is produced as a result of ventricular contraction.c waveThe x descent is interrupted by second positive wave the \'c\' wave. It is produced by bulging of the tricuspid valve into the right atrium during R V isoivolumetric contraction.vwaveIt is the positive systolic wave. It result from increase in the blood volume in the venacava during systole, when the tricuspid valve is closed.y descentFollowing the "v wave " this is a negative descending limb referred to as they descent or diastolic collapse. It is due to tricuspid valve opening and rapid inflow of blood into the right ventricle.So there areThree visible major positive waves (a.c and v) andTwo negative waves (x and y).', 'role': 'assistant'}]