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Physiology of the Cardiovascular System

Physiology of the Cardiovascular System. Conduction System. SA Node. Pacemaker Initiates the normal cardiac impulse Has intrinsic rhythm , initiates impulses at regular intervals even without stimulation by nerve impulses SA node  interatrial bundle left atrium contraction of atria

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Physiology of the Cardiovascular System

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  1. Physiology of the Cardiovascular System

  2. Conduction System

  3. SA Node • Pacemaker • Initiates the normal cardiac impulse • Has intrinsic rhythm, initiates impulses at regular intervals even without stimulation by nerve impulses • SA nodeinteratrialbundleleft atrium contraction of atria • SA node3 internodalbundlesAV node

  4. AV node • Impulse passes slowly thru AV node then speed up thru the AV bundle & Purkinje fibers causing ventricles to contract

  5. Ectopic pacemaker • If SA node loses its ability to generate impulse, another portion of conduction system can generate impulse but will be at a slower rate

  6. Electrocardiogram (EKG) • Graphic record of heart’s electrical activity

  7. P wave • Depolarization of the atria, passage of electrical impulse from SA node thru the atria

  8. QRS complex • Represents depolarization of ventricles • Repolarization of atria also occuring

  9. T wave • Repolarization of ventricles

  10. http://www.youtube.com/watch?v=qHjbEYUfzH8

  11. Cardiac cycle • Complete pumping cycle • Systole (contraction) & diastole (relaxation) of atria & ventricles

  12. Atrial systole • Contraction of atria • Blood into ventricles • AV valves are open • Semilunar valves closed • P wave of EKG

  13. Isovolumetric Ventricular Contraction • Between start of ventricular systole & opening of semilunar valves • Ventricular volume constant • Ventricular systole coincides with R wave of ECG & 1st heart sound

  14. Ejection • Semilunar valves open • Initial rapid ejection: marked increase in aortic & ventricular pressure • Longer reduced ejection: T wave appears • Residual volume of blood remains in ventricles after ejection

  15. Isovolumetric Ventricular Relaxation • Ventricular diastole • Period between closure of semilunar valves & opening of AV valves • Second heart sound is heard

  16. Passive ventricular filling • Av valves forced open by increasing intra atrial pressure

  17. Heart sounds • “lubb-dupp” • First sound caused by contraction of ventricles & vibrations of the closing of AV valves • Second sound caused by vibrations of the closing of semilunar valves

  18. Anxiety, fear, anger Exercise Increased body temperature Grief Decreased body temperature Factors that affect heart rate

  19. Blood pumping action of respirations Skeletal muscle contraction Venous Return to Heart

  20. Blood pressure • Sphygmomanometer • Systolic pressure: force with which the blood is pushing against the artery when ventricles are contracting • Diastolic pressure: force of blood when ventricles are relaxed

  21. Pulse • Alternate expansion & recoil of an artery • Two factors are responsible • Intermittent injections of blood from heart • Elasticity of arterial walls

  22. Pulse sites • Radial artery- wrist • Temporal artery- temples • Carotid artery- neck • Brachial artery- elbow • Popliteal artery- behind knee • Dorsalispedis- top of foot

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