Cardiovascular System: Intrinsic Conduction System 1. autorhythmic cardiac, impulses (action potentials) 2. heart depolarization 3. a. initiates the depolarizing impulse and sets the pace for the entire heart b. link between the SA node and the AV node c. delay occurs allowing atria to contract d. link between atria and ventricles e. convey impulses down the interventricular septum f. convey the depolarizations throughout the ventricular walls 4. contractile 5. ECG—electrocardiogram (or EKG) 6. a. atrial depolarization b. ventricular depolarization c. ventricular repolarization 7. QRS complex 8. atrial, contraction 9. QRS complex 10. tachycardia Cardiovascular System: Cardiac Action Potential 1. Through gap junctions 2. contract 3. 1. sodium, into 2. potassium, out of 3. fast calcium, into 4. positive 5. decreased, potassium, sodium 6. –40, fast calcium channels 7. potassium, repolarization 8. Na+-K+ ATPase 9. Sarcoplasmic reticulum 10. Sodium, calcium, and potassium 11. a. fast sodium channels b. slow calcium channels c. potassium channels 12. Sodium channels 13. Calcium channels Cardiovascular System: Cardiac Cycle 1. differences in blood pressure 2. Chamber Valve Chamber/Vessel Right ventricle Pulmonary semilunar Pulmonary trunk Left ventricle Aortic semilunar Semilunar aorta Left atrium Mitral Left ventricle Right atrium Tricuspid Right ventricle 3. a. mid to late, diastole b. atrioventricular, AV 4. Intraventricular pressure is greater than atrial pressure. 5. Intraventricular pressure is greater than pressure in the pulmonary trunk and aorta. 6. Blood flow back toward the heart (due to aortic pressure being greater than intraventricular pressure). 7. Atrial pressure is greater than intraventricular pressure. 8. With hypertension, the ventricular pressure must rise higher to open the semilunar valves. For the same increase in pressure in a normotensive person, less blood is ejected in a hypertensive person. Thus, the heart of someone with hypertension must work harder to eject the same stroke volume. 9. 70 10. Phase AV Valves Semilunar Valves Ventricular filling Open Closed Isovolumetric Closed Closed Ventricular ejection Closed Open Isovolumetric Closed Closed contraction relaxation Cardiovascular System: Cardiac Output 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. The amount of blood pumped out by each ventricle in one minute CO = HR SV The amount of blood ejected from each ventricle in one heartbeat SV = EDV – ESV a. 75 beats/minute (bpm) b. 70 ml/beat c. 120 ml d. 50 ml CO = HR SV = 75 beats/minute x 70 ml/beat = 5250 ml/minute or 5.25 L/minute HR SV CO a. SNS b. Venous return c. Exercise d. Calcium e. HR An increase in contractility leads to an increase in the force of contraction. An increase in filling time leads to an increase in end diastolic volume (Frank Starling mechanism). 3 bottles (6 liters)