are you a nursing student that wants to cut your study time but over 60% well you can head over to simplenursing.com youout and sign up for free hi everybody Dr Mike here in this video we're going to take a look at the conduction of the cardiac system this is the electrical current that moves its way through the muscle of the Heart The myocardium in order to tell it to contract now the first thing you need to remember is that heart muscle is specialized and when we look at it under a microscope all the heart muscle cells are connected Ed to one another like this and they got these little gaps between now this is important because what you're going to find is that these cells like any excitable cell of the body like neurons for example at rest they have a negative charge associated with them interesting and what happens is if you want these muscle cells to contract you need to turn that negative charge into a positive charge and when it does so goes from negative to positive it spreads that wave of charge change from one to the other very easily we call this depolarization depolarization this is when it goes from negative charge to a positive charge and muscles won't contract unless this happens so knowing this now what we're going to do is we're going to have a look at the heart and have a look at how this depolarization event or negative to positive positive charge change happens through the heart to tell it to contract it all begins here this area at the Atria is a specialized type of tissue that we call the Sino atrial node also known as the SA node now sinos is referring to sinus it sets what we call the sinus rhythm this is the pacemaker of the heart sets the Rhythm about 60 to 100 beats per minute now at rest it's negatively charged right but what it does is it spontaneously goes positive like I showed you before and if it spontaneously goes positive it's going to send a wave of positive charge throughout the muscle of the heart specifically the muscle of the Atria remember two atria at the top two ventricles down the bottom this is the muscle associated with it so sinal node muscle uh isssue is negative it then turns positive and sends a wave of positive charge through the atrial muscle in that manner so it goes like this spreads this positive charge through positive positive positive positive positive moving all the way through struggling to stay afloat during nursing school let me help you achieve our 96% pass rate by heading over to simplenursing.com youube and signing up for free