1. C ARDIOVASCULAR S YSTEM P. 347-352 Heart Actions

2. C ARDIAC C YCLE One complete heartbeat Atrial contraction, ventricular relaxation Atrial relaxation, ventricular contraction Pressure within heart Rises and falls as chambers fill and empty Atrial or Ventricular Contraction (Systole) Pressure Pressure increases sharply Atrial or Ventricular Relaxation Diastole Pressure Pressure goes back down AV Valves are opening and closing during pressure changes

3. H EART S OUNDS Vibrations in heart tissue produce opening and closing of valves Heard as LubDup through stethoscope Lub Heard during ventricular contraction (AV valves are closing) Dup Heard during ventricular relaxation (pulmonary and aortic valves are shutting) MurMur Abnormal sound Usually occurs when heart valves don’t properly close causing blood to leak through

4. C ARDIAC M USCLE F IBERS Act like skeletal muscles but connect to a network of sending impulses to contract all as a unit. Functional Syncytium Mass of merging cells that act as a unit

5. C ARDIAC C ONDUCTION S YSTEM Coordinates events of cardiac cycle Sinoatrial Node (SA Node) Small mass of elongated specialized cardiac muscle tissue Cells reach threshold on own and membranes contract one another Initiate impulses that spread into the surrounding myocardium and stimulate cardiac muscle fiber to contract Rhythmic activity 70-80 impulses/min. (Pulse) Pacemaker (Rhythmic contracting)

6. A TRIOVENTRICULAR N ODE (AV N ODE ) Located in septum Receives slow impulse After received impulse AV node sends it on to AV Bundle Purkinje Fibers Allow transmission of impulse for contraction of the ventricles and pushes blood on out to aorta

7. ECG/EKG…E LECTROCADIOGRAM Recording of the electrical changes in the myocardium during cardiac cycle Deflections = waves on paper Polarization and repolarization causes pen to move

8. P QRS T W AVES P wave Depolarization, contraction of atriums QRS Complex Waves correspond to depolarization of ventriular fibers that contract ventricles, atriums relax, ventricles contract T wave Ventricles relax, pattern ends P-R Interval Wave travels through AV node, AV bundles, bundle branches and purkinje fibers S-T Segment Time for complete excitation of ventricles Q-T Interval Time required for complete excitation and recovery of ventricles T-P Interlude Time from completion of ventricular repolarization to next atrial excitation

10. R EGULATION OF C ARDIAC C YCLE Read p. 356 Arrhythmia Abnormal heart rhythm http://www.youtube.com/watch?v=xw4nDMgTOrw

11. R EVIEW Describe the pressure changes in the atria and ventricles during a cardiac cycle. What causes heart sounds? What is a functional syncytium? How is a cardiac impulse imitated? How is a cardiac impulse transmitted from the right atrium to the other heart chambers?