1. Cardiac Conduction System

2. (1) Conduction System of Heart Conduction System = Heart Beat & Pumping Cardiac Contractions = Unconscious –Autonomic Nervous System  decrease or increase heart rate depending on circumstance

3. (2) Depolarization of the Heart Generate Action Potential & Depolarization: –Atria  Ventricles Depolarization Path: 1.SA Node  AV Node 2.Atria Contract 3.(Delay)  AV Bundle 4.Ventricles Contract (Blood ejected out of arteries, leaving heart)

4. http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter22/ani mation__conducting_system_of_the_heart.html

5. (3) Nodes & Bundles Sinoatrial Node (SA Node) –Right atrium –Starts each heart beat & sets rate –“Pacemaker” Atrioventricular Node (AV Node) = Left atrium AV Bundle = –Bundle Branches (along septum) –Purkinje Fibers (along entire muscular wall of heart)

7. (4) Cardiac Cycle Diastole = Relax –Blood passively filling atria Systole = Contract –Ventricles contract –Blood Ejected out of heart

9. (5) Diastole 1.Ventricles relax 2. Semilunar valves closed 3. Ventricular Presure < Atrial Pressure –AV valves open –Ventricles fill with blood 4. Atria contract and force blood remaining in chambers into ventricles

11. (6) Systole 1.Pressure increases in ventricles -Filled with blood 2.AV valves close 3. Pressure in ventricles > Arteries leaving heart -Semilunar valves open -Blood rushes out of ventricles 4. Atria are relaxed and begin to fill back up

13. (7) Heart Beat You hear something like “lub” “dup” –“lub” = closing of AV valves During ventricular systole –“dup” = closing of semilunar valves During early diastole You should NOT hear blood flow –You’ll hear it if flow is interrupted by blockage http://www.csulb.edu/org/college/bme/respiratory _sounds/heart.wav

14. (8) Cardiac Output Cardiac Output –A–Amount of blood pumped out by each ventricle / 1 minute –C–Cardiac Output = Heart Rate x Stroke Volume –C–CO = (HR)(SV) Stroke Volume –V–Volume of blood pumped out by ventricle –I–Increase of SV = Increase of ventricular force + contraction Average Stroke Volume = 0.2L Average Cardiac Output = 15L/min

15. (9) Starling’s Law Starling’s Law of the Heart: –Degree of cardiac muscle extension before contraction –Increase Extension = Stronger Contraction –Degree of Extension  result of percent filling of ventricles