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': 'Which of the following is responsible for Bezold-Jarisch Reflex \nSelect and explain. \nA. Serotonin, B. Histamine, C. Prostaglandin, D. Angiotensin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Serotonin(Ref: Ganong, 25th ed/p.592, 662)Bezold-Jarisch reflexIntracardiac injections of chemicals like serotonin, veratridine, capsaicin, phenylbiguanide activates this reflexAfferents for this reflex travel through unmyelinated vagal C fiber endingsThe reflex responses are:#Apnea followed by rapid breathing#Hypotension#BradycardiaClinical importance of Bezold-Jarisch reflex#This reflex is responsible for sinus bradycardia seen during myocardial infarction#This reflex is one of the causes for profound bradycardia and circulatory collapse after spinal anesthesia', 'role': 'assistant'}]