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PHYSIOLOGY OF THE HEART NOTES

PHYSIOLOGY OF THE HEART NOTES. Cardiac Conduction System. SA node - (pacemaker) sinoatrial AV node – atrioventricular AV bundle. SA node - (pacemaker) sinoatrial. Initiates impulses that contract the heart without brain or nerve signals. Located at the right atrium

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PHYSIOLOGY OF THE HEART NOTES

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  1. PHYSIOLOGY OF THE HEART NOTES

  2. Cardiac Conduction System • SA node - (pacemaker) sinoatrial • AV node – atrioventricular • AV bundle

  3. SA node - (pacemaker) sinoatrial • Initiates impulses that contract the heart without brain or nerve signals. • Located at the right atrium • Impulse travels to left atrium and contracts it.

  4. AV node - atrioventricular • Impulse slowly moves through this node in right atrium.

  5. AV bundle • Located in septum • End in purkinje fibers - in both ventricles • Ventricles are stimulated to contract.

  6. Contractions • Normal average 70-75 beats/min. • Emotions, exercise, hormones, pain, anxiety, fear, and anger can affect this.

  7. Electrocardiogram (ECG) • Graphic record of the heart’s action currents.

  8. Electrocardiogram (ECG) • An ECG is printed on paper covered with a grid of squares. Notice that five small squares on the paper form a larger square. The width of a single small square on ECG paper represents 0.04 seconds. To successfully interpret ECGs, you must have this value committed to memory.

  9. Electrocardiogram (ECG) • If each small square represents 0.04 seconds, then a second will be 25 small squares across. If you print out a minute's worth of your heart's electrical activity, the paper would be 1500 small squares wide. If something on an ECG is, let's say, 12 small squares in width, that means that it lasted 12 x 0.04, or almost half a second. A common length of an ECG printout is 6 seconds; this is known as a "six second strip."

  10. Electrocardiogram Waves • P-wave • Depolarization (contraction) of atria. • QRS-wave • Depolarization (contraction) of ventricle • T-wave • Repolarization (relaxation) of ventricles

  11. Cardiac cycle • Atrial systole - contracting atria forces blood into ventricle. P-wave of ECG • Isovolumetric contraction - blood volume in ventricles remains constant. QRS-wave of ECG (1st heart sound) • Ejection - blood ejected into pulmonary artery and aorta. T-wave

  12. Cardiac cycle continued • Isovolumetric relaxation - relaxation of ventricles (second heart sound) • Rapid ventricular filling - return of venous blood • Increases atrial pressure until av valves (tricuspid and bicuspid) open and blood rushes into ventricles. • Reduced ventricular filling - increase in ventricular pressure and volume will slow blood filling.

  13. Blood Pressure • Sphygmomanometer - measures air pressure = to blood pressure

  14. Blood Pressure • Systolic pressure - 1st sound • blood pushing against artery walls when ventricles contract. • Diastolic pressure - 2nd sound • closing of valves, short sharp sound

  15. Directions for Taking Blood Pressure • Pump pressure until no pulse is heard • Release air until a spurt of blood is heard coming through. (systolic) • Continue until sound stops (diastolic)

  16. Video Clip http://www.nlm.nih.gov/medlineplus/ency/anatomyvideos/000021.htm Cardiac Conduction System http://www.healthination.com/Conditions/Videos/Congestive-Heart-Failure/The-Failing-Heart http://www.healthination.com/topics.php?page=congestive_heart_failure Congestive Heart Failure Heart Attack ECG http://www.sciencelearn.org.nz/Contexts/See-through-Body/Sci-Media/Animations-and-Interactives/Label-the-heart Drag and drop Tutorial

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