1. Circuits Chambers Valves (one-way-flow) Myocardiocytes The Heart

2. Volumes? Pressures? heart –> lungs –> heart heart –> body –> heart Artery = Vein =

3. Trace a RBC!

4. The Heart has 4 Valves To prevent retrograde flow of blood. 2 atrioventricular valves (AV) between the atria and ventricles. 1) Right AV (tricuspid) valve 2) Left AV (bicuspid/mitral) valve

5. 2 semilunar valves between a ventricle and artery. 1) Aortic semilunar valve 2) Pulmonary semilunar valve Two heart sounds: “Lub” and “Dup” 2. Closure of Semilunar valves = “Dup” 1. Closure of AV valves = “Lub” http://www.openheartsurgery.com/heart_murmur.html

7. Normal Heart Valves Problems Opening: Stenosis – narrowing of valve, when a valve doesn't open completely. Turbulence = noise = murmur. Problems Closing: Prolapse –overlapping or when valve doesn't close tightly. Also termed valvular insufficiency (regurgitation) Retrograde flow = noise = murmur. Disorders of Heart Valves Problem Heart Valves

8. Myocardiocytes: 1) Autorhythmic 2) Contractile

10. Action Potentials for Autorhythmic Myocardiocytes

11. stimulus Action Potentials for Contractile Myocardiocytes

12. Myocardiocytes: Calcium induced Calcium release

13. Graded Contraction of Heart Force generated by myocardiocyte contraction is: 1. Proportional to amount of Calcium ions (Ca 2+ )  [Ca 2+ ] => more crossbridges, more force & speed.

15. Graded Contraction of Heart Force generated by myocardiocyte contraction is: 2. Modulated by Autonomic N.S. => Sym  HR and  Force => Para  HR 1. Proportional to amount of Calcium ions (Ca 2+ )  [Ca 2+ ] => more crossbridges, more force & speed.

16. Sympathetic – speeds heart rate by  Ca 2+ influx. Parasympathetic – slows rate by  K + efflux,  Ca 2+ influx.

17. Graded Contraction of Heart Force generated by myocardiocyte contraction is: 2. Modulated by Autonomic N.S. => Sym  HR and  Force => Para  HR 1. Proportional to amount of Calcium ions (Ca 2+ )  [Ca 2+ ] => more crossbridges, more force & speed. 3. Stretch-Length-Tension Relationship  stretch, =>  Ca 2+ entering =>  contraction force

18. Factors Influencing Stroke Volume

19. The Cardiac Cycle http://www.youtube.com/watch?v=rguztY8aqpk

20. 1.Late Diastole: “Heart at rest” all chambers relaxed filling with blood (passive filling ~ 80% full). 2. Atrial Systole: atria contract, adds the last 20% of blood to ventricles (top off ventricles) Occurs after P-wave on EKG The Cardiac Cycle: Mechanical Events of the Heart End Diastolic Volume (EDV) = Maximum ventricular volume*

21. 3. Ventricular Systole (part 1): Ventricular contraction begins -  Pressure (P). Closure of AV valves = 1 st heart sound ("lub") Sealed Compartment – all valves are closed. Isovolumetric ventricular contraction: => pressure builds as volume stays the same.

22. 4. Ventricular Systole (part 2): Ejection phase:  P pushes open semilunar valves, blood forced out into artery leaving ventricle. Pulmonary Semilunar => 25 mmHg (minimum pressure) Aortic Semilunar => 80 mmHg (minimum pressure) End Systolic Volume (ESV) = volume remaining in heart after ejection (~½)*. Stroke Volume = EDV - ESV (ml/beat)

23. 5. Ventricular Diastole: Relaxation of ventricles, artery back flow slams semilunar valves shut = 2 nd heart sound ("dup"). The AV valves then open, refilling starts – back to start of cycle. Sealed Compartment again – all valves are closed. Isovolumetric ventricular relaxation: =>  pressure as volume stays the same.

24. Cardiac Output (C.O.) = Heart Rate x Stroke Volume *Heart Rate = beats/min *Stroke Volume = EDV-ESV (vol/beat) e.g. calculation:

25. Electrical Conduction System Sino Atrial (SA) Node Atrial Ventricular (AV) Node AV Bundle (of His) L and R Bundle Branches Purkinje Fibers

26. Trace of an ElectroCardioGram (ECG)

27. The ECG P wave: PR interval: QRS complex: T wave:

29. Ventricular Assist Devices http://www.youtube.com/watch?v=D3ZDJgFDdk0