NEURO 661 Lecture Notes - Lecture 6: Cytosol, Website Wireframe, Sinoatrial Node
Document Summary
The physiologic processes associated with heart contraction are organized into two major events. These are presented diagrammatically in gure 19. 15 and include the following: Electrical activity is initiated at the sa node, and an action potential is then transmitted through the conduction system. The action potential spreads across the sarcolemma of the cardiac muscle cells, causing sarcomeres within cardiac muscle cells to contract. These events occur twice in cardiac muscle cells during a heartbeat, rst in the cells of the atria and then in the cells of the ventricles. Events of cardiac muscle cells occur twice in one heartbeat; once in the cells of the atria and once in the cells of the ventricles. Here we discuss the events associated with the conduction system including the physiologic conditions of nodal cells at rest and how they serve as the heart"s pacemaker. The processes associated with cardiac muscle cells are described in section 19. 7.
