Physiology 2130 Chapter Notes - Chapter 8: Qrs Complex, Purkinje Fibers, Heart Valve
25 Dec 2016
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State the four main functions of the cardiovascular system. Transport oxygen and nutrients to cells of body. Describe the different types of myocardial cells and explain their functions. Contractile cells: form most of the walls of atria and ventricles. Action/myosin: arranged in bundles of myofibrils surrounded by sarcoplasmic reticulum. Different from skeletal muscle: have one nucleus but more mitochondria. Nodal/conducting cells: able to spontaneously generate action potentials without help of nervous input. Rapidly conduct action potentials to atrial and ventricular muscle. Provide self-excitatory system for heart to generate impulses and transmission system for rapid conduction of impulses throughout heart. Explain the origin of self-excitability and give two characteristics of the sinoatrial node which lead to self-excitability. Sinoatrial node (sa node): generally origin of action potentials, is first area of heart to spontaneously depolarize. Action potential: travels through atria then to av node then bundle of his, through purkinje fibers to ventricular muscle. 2 characteristics of sa node important for self-excitability.
