1. Cardiovascular System The Heart

2. Both Sides (now)

3. Functions of the Heart Generating blood pressure Routing blood – Heart separates pulmonary and systemic circulations Ensuring one-way blood flow – Heart valves ensure one-way flow Regulating blood supply – Changes in contraction rate and force match blood delivery to changing metabolic needs

4. Size, Shape, Location of the Heart Size of a closed fist Shape – Apex: Blunt rounded point of cone – Base: Flat part at opposite of end of cone Located in thoracic cavity in mediastinum

5. Pericardium

6. Heart Wall Three layers of tissue – Epicardium: This serous membrane of smooth outer surface of heart – Myocardium: Middle layer composed of cardiac muscle cell and responsibility for heart contracting – Endocardium: Smooth inner surface of heart chambers

7. Heart Wall

8. External Anatomy Four chambers – 2 atria – 2 ventricles Major veins – Superior vena cava – Pulmonary veins Major arteries – Aorta – Pulmonary trunk

9. External Anatomy

10. Coronary Circulation

11. Heart Valves Atrioventr icular – Tricuspid – Bicuspid or mitral Semiluna r – Aortic – Pulmonary Prevent blood from flowing back

12. Heart Valves

13. Function of the Heart Valves

14. Blood Flow Through Heart

15. Systemic and Pulmonary Circulation

16. Heart Skeleton Consists of plate of fibrous connective tissue between atria and ventricles Fibrous rings around valves to support Serves as electrical insulation between atria and ventricles Provides site for muscle attachment

17. Conducting System of Heart http://www.youtube.com/watch?v=te_SY3Me Wys&feature=related

18. Electrical Properties Action potentials are: Sodium ions enter the cell and begin the depolarization Calcium ions follow and extend the depolarization even further. Once Calcium stops moving inward, Potassium ions move out and repolarization begins

19. Specific to the Heart... Action Potential is: – Rapid depolarization of heart muscle – Rapid, partial early repolarization of heart muscle – Via Voltage-gated channels – CONFUSED?

20. Refractory Period The important part of this cycle is the period where the cells reset and prepare for the next wave. This is called the refractory period because the cells are refractory to (or unaffected by) further stimulation

21. Refractory Period The time between Absolute: Cardiac muscle cell completely insensitive to further stimulation Relative: Cell exhibits reduced sensitivity to additional stimulation Long refractory period prevents tetanic contractions

22. Imagine, if you will, a toilet. When you pull the handle, (initiate an impulse) water floods the bowl(kinda' like contraction!). This event takes a couple of seconds and you cannot stop it in the middle. Once the bowl empties, the flush is complete. Now the upper tank is empty. If you try pulling the handle at this point, nothing happens (absolute refractory?) Wait for the upper tank to begin refilling (Potassium moves back). You can now flush again, but the intensity of the flushes increases as the upper tank refills (relative refractory...)

23. ECG Action potentials through myocardium during cardiac cycle produces electric currents than can be measured Pattern – P wave Atria depolarization- firing – QRS complex Ventricle depolarization Atria repolarization – T wave: Ventricle repolarization- reloading

24. PQRST the P-Wave, representing the impulse across the atria to the A/V Node; The QRS representing the impulse as it travels across the ventricles; the T-Wave, representing the repolarization of the ventricles

25. Cardiac Arrhythmias Tachycardia: Heart rate in excess of 100bpm Bradycardia: Heart rate less than 60 bpm Atrial Fibrillation: describes a condition in which the atrial tissue randomly generates action potentials from many different regions

26. Alterations in Electrocardiogram

27. Cardiac Cycle Heart is two pumps that work together, right and left half Repetitive contraction (systole) and relaxation (diastole) of heart chambers Blood moves through circulatory system from areas of higher to lower pressure. – Contraction of heart produces the pressure

28. Cardiac Cycle

29. Heart Sounds First heart sound or “lub” (S1- closing of the tricuspid and mitral valves) – Atrioventricular valves and surrounding fluid vibrations as valves close at beginning of ventricular systole Second heart sound or “dub” (S2- closing of the pulmonic and aortic valves as blood leaves right and left ventricles) – Results from closure of aortic and pulmonary semilunar valves at beginning of ventricular diastole, lasts longer Third heart sound (occasional) – Caused by turbulent blood flow into ventricles and detected near end of first one-third of diastole

30. Location of Heart Valves

31. Heart Homeostasis Effect of blood pressure – Baroreceptors monitor blood pressure Effect of pH, carbon dioxide, oxygen – Chemoreceptors monitor Effect of extracellular ion concentration – Increase or decrease in extracellular K + decreases heart rate Effect of body temperature – Heart rate increases when body temperature increases, heart rate decreases when body temperature decreases

32. Effects of Aging on the Heart Gradual changes in heart function, minor under resting condition, more significant during exercise Hypertrophy of left ventricle Maximum heart rate decreases Increased tendency for valves to function abnormally and arrhythmias to occur Increased oxygen consumption required to pump same amount of blood

33. Pathology (1) Cardiomyopathy- disease of the heart muscle Phlebitis - inflammation of a vein Aneurysm - local widening of an artery Cyanosis- bluish color of skin Ischemia- diminished blood flow Angina - chest pain

34. Pathology (2) Petichiae- small, pinpoint hemorrhages Coronary Artery Disease-blocked arteries leads to ischemia Congestive heart failure- inability of heart to pump adequately Claudication- pain and weakness in a limb as result of decreased blood flow

35. END Let’s Do Respiratory!