Physiology of the Heart

Physiology of the heart You should understand by now that the Physiology of the Heart refers to the function of the heart You need to be familiar with the conduction system of the heart, the cardiac cycle, sounds of the heart, and cardiac out put You should understand by now that the Physiology of the Heart refers to the function of the heart You need to be familiar with the conduction system of the heart, the cardiac cycle, sounds of the heart, and cardiac out put

Conduction System of the Heart Cardiac muscle is unique because it can contract spontaneously and independently even if all nervous connections to the heart are severed These contractions however, are not erratic but regular and steady in rhythm Cardiac muscle is unique because it can contract spontaneously and independently even if all nervous connections to the heart are severed These contractions however, are not erratic but regular and steady in rhythm

Beats per minute The atrial cells of the heart beat roughly 60 times per minute The ventricular cells of the heart beat only times per minute Without some unifying system to control them the heart would be an uncoordinated and inefficient pump The atrial cells of the heart beat roughly 60 times per minute The ventricular cells of the heart beat only times per minute Without some unifying system to control them the heart would be an uncoordinated and inefficient pump

Intrinsic Conduction The Intrinsic Conduction System (Nodal System) of the heart is made of very specialized cardiac tissue that is a cross between muscle and nervous tissue The Intrinsic Conduction System (Nodal System) of the heart is made of very specialized cardiac tissue that is a cross between muscle and nervous tissue

Intrinsic Conduction We see 2 large ovals which are the nodes of the system The sinoatrial node (SA Node) acts as the pace maker of the heart The atrioventricular node (AV Node) slows the impulse before sending it to the ventricles We see 2 large ovals which are the nodes of the system The sinoatrial node (SA Node) acts as the pace maker of the heart The atrioventricular node (AV Node) slows the impulse before sending it to the ventricles

Cardiac Cycle Two most important terms in understanding cardiac cycle are Systole and Diastole Systole is heart contraction Diastole is heart relaxation Two most important terms in understanding cardiac cycle are Systole and Diastole Systole is heart contraction Diastole is heart relaxation

5 Phases of Cardiac Cycle

Cardiac sounds In a healthy heart you should be able to hear a steady “lub-dub” sound of contraction We have to understand that there is a sequence to the sounds lub-dub, pause, lub-dub, pause In a healthy heart you should be able to hear a steady “lub-dub” sound of contraction We have to understand that there is a sequence to the sounds lub-dub, pause, lub-dub, pause

“Lub” and “Dub” sounds The “lub” sound we hear is from the the closing of the AV valves This is then followed by a pause The “dub” sound we hear is from the closing of the semilunar valves The “lub” sound we hear is from the the closing of the AV valves This is then followed by a pause The “dub” sound we hear is from the closing of the semilunar valves

Blood flow It is important to realize that blood flows silently as long as the flow is smooth and un-interupted If the flow becomes irregular we can hear murmurs It is important to realize that blood flows silently as long as the flow is smooth and un-interupted If the flow becomes irregular we can hear murmurs