Explore the intricacies of the extrinsic cardiac conduction system in this comprehensive lecture video. Delve into blood pressure regulation, beta1-adrenergic receptors, and the role of adenylate cyclase. Examine the function of protein kinase A and the sympathetic nervous system in cardiac physiology. Investigate cross-bridge formations, contractility, heart rate, and blood pressure relationships. Gain insights into the refractory period and its significance in cardiac electrophysiology. Learn from Professor Zach Murphy's expert presentation, concluding the electrophysiology of the heart series.