ANP 1105 Lecture Notes - Lecture 9: Calcium Channel Blocker, Qrs Complex, Heart Sounds

• School: University of Ottawa
• Department: Anatomy and Physiology
• Course: ANP 1105
• Professor: Simon Lemaire

Document Summary

The intrinsic cardiac conduction system is made of non contractile cardiac cells that are specialized to initiate and distribute impulses throughout the heart, so that it depolarizes and contracts in an orderly manner. 1% of cardiac fibers are autorhythmic cardiac pacemaker cells therefore they have the ability to depolarize spontaneously, pacing the heart. They have unstable resting potentials, and because of their spontaneity they are called pacemaker potentials/prepotentials that initiate action potentials that travels throughout the heart. Depolarization is caused by the calcium influx through their channels: repolarization, due to the calcium channels inactivating and potassium channels opening. This brings in more potassium which brings the membrane potential back to the most negative voltage. Cardiac pacemaker cells are usually found in the sinoatrial and atrioventricular nodes. The sympathetic nervous system increases the rate and force of the heartbeat. The parasympathetic nervous system slows the heart. The cardiac centers are located in the medulla oblongata.