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The Heart

The Heart. Anatomy and Physiology. Cardiovascular System (Overview). Heart beats over 100,000 times a each day Pumps a total of 8000 liters of blood Closed System Pulmonary Circuit/ Systemic Circuit

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The Heart

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  1. The Heart Anatomy and Physiology

  2. Cardiovascular System (Overview) • Heart beats over 100,000 times a each day • Pumps a total of 8000 liters of blood • Closed System • Pulmonary Circuit/ Systemic Circuit • Works with the respiratory system and blood for the delivery of oxygen and nutrients and removal of waste

  3. Vessels • Arteries (Efferent): Blood Away • Most cases oxygen rich • Veins (Afferent): Blood Toward • Most cases oxygen poor • Capillaries: vessels in between/ exchange vessels. • Gas exchange: Semi-permeable membrane

  4. Anatomy of the Heart • Four Chambers • Upper Chambers • Atrium (Atria) • Lower Chambers • Ventricles • Position within the thorax

  5. Thoracic Location • Anterior Chest/ Posterior to the sternum • Lies slightly to the left of the midline • Sits at an angle • Rotated toward the left side • Surrounded by the pericardial cavity

  6. Pericardium • Fist into the center of a balloon • Subdivided: Visceral and Parietal • Pericardial Sac: 10-20 ml of pericardial fluid • Secreted by the pericardial membranes • Lubricant • Pericarditis

  7. Superficial Anatomy of the Heart • Atria, the top chambers: Auricle • Grooves • Coronary Sulcus • Anterior interventricular sulcus • Posterior interventricular sulcus • Fat Deposits for cushion • Base and Apex

  8. Internal Anatomy • Interatrial Septum • Interventricular Septum • Atrioventricular Valves

  9. Right Atrium • Blood Received from Superior Vena Cava (SVC) and Inferior Vena Cava (IVC) • Coronary Sinus also returns blood to the heart • Foramen Ovale: Oval window that connects atria during the time when fetus in the uterus. Closes after birth

  10. Right Ventricle • Cusps (Tricuspid): An AV Valve • Connected by the Chordae Tendineae to the papillary muscles • Allows for the doors to swing open, but only in one direction • Pulmonary Trunk, Pulmonary Semi-Lunar valves. • Into Pulmonary Arteries (left and right)

  11. Left Atrium • Blood returning from the lungs • Four Pulmonary Veins • Pools in the atria • Through the Mitral Valve (bicuspid) AV Valve

  12. Left Ventricle • Pumps at great pressure, systemic circulation • Aortic Semi-Lunar Valve • Aortic Arch • Descending Aorta • Pulmonary Trunk is attached to the Aortic Arch by the Ligamentum Arteriosum • Aortic Rupture/Aortic Stenosis

  13. Left Ventricle Large, must push harder Six to seven times as much force Thicker wall When it pumps it bulges into the right ventricle Right Ventricle Smaller, less pressure Assisted by the left ventricle as both ventricles pump at the same time Structural Difference

  14. Closer Look at the Valves • AV Valves • Prevents backflow into atria • During vent relax, loose, valves open • Vents contract, valves close • Semi-Lunar Valves • Prevents backflow into vents • Support each other like legs of a tripod • MVP • Rheumatic Fever

  15. The Heart Wall • Three Layers • Epicardium • Myocardium • Endocardium

  16. Cardiac Muscle Tissue • Muscle cells are intercalated discs • Calcium plays a role • Automaticity • Smaller than typical skeletal muscle cell

  17. Blood Supply to Heart • Myocardium needs blood • Sensitive to low blood supply • Coronary Circulation • Right Coronary Artery • Rt Atrium • Portions of both vent • SA and AV nodes • Posterior interventricular branch

  18. Blood supply (cont) • Left Coronary Artery • Lt atrium, Lt vent, Intervent septum • Gives rise to circumflex branch and anterior interventricular branch • Cardiac Veins • Coronary Sinus • Posterior and middle cardiac veins • Small cardiac veins, anterior cardiac veins

  19. Innervation of the Heart • Cardiac centers of the medulla • Cardioacceleratory Center • Cardioinhibitory Center • Vagus Nerve • Baroreceptors and Chemoreceptors

  20. Conduction System • Sinoatrial Node (SA) • Atrioventricular Node (AV) • Internodal pathways (Bundle Branches: Bundle of His) • Purkinje Fibers

  21. SA Node • Pacemaker Cells • 50 msec from SA to AV • Stimulates rt and lt atria • Action spreads through cell to cell contact

  22. AV Node • Less efficient pathways • 100 msec • Junction as a pausing location • Important so that the atria depolarize before the ventricles

  23. AV Bundle and Bundle Branches • Only electrical connection between atria and ventricles • Left bundle branch serves left ventricle • Conduct the impulse to the purkinje fibers • Purkinje rapidly fire

  24. ECG or EKG • P wave • QRS Complex • T wave • P-R Interval (no more than .2 sec) • Q-T Interval • Rate/Rhythm • ST Segment

  25. Heart Attacks • Myocardial Infarction (MI) • Coronary Thrombosis • Cardiac Enzymes • Lactate Dehydrogenase (LDH) • Serum Glutamic Transaminase (SGOT) • Creatine Phosphokinase (CPK) • CPK-MB: Special CPK in cardiac muscle

  26. Cardiac Cycle • The period between start of one heart beat and the next is a single cardiac cycle • Contractions/Relaxations • Systole (Contraction) Pump • Diastole (Relaxation) Fill • Fluid moves from high to low pressure • Atrial and ventricular systole not at same time

  27. Phases • Atrial Systole (Beginning) • 100 msec • Blood pushed through AV valves • Ventricles already 70% full, Atria tops off (70% is passive from previous cardiac cycle) • At end of Atrial Systole, vents have max blood: End Diastolic Volume (130ml)

  28. Phases (Cont) • Ventricular Systole • 270 msec • Vent contract at first it is isovolumetric contraction all heart valves closed, no blood flow yet • As pressure increases, semilunar valves open (ventricular ejection) • Pressures slowly decline, before the valves close, blood returns to vents • Stroke volume 80 ml (60%) of EDV • End-Systolic pressure 50 ml 40% of EDV

  29. Phases (Cont) • Ventricular Diastole • 430 msec • All valves close • Vent myocardium resting • Vent pressure is higher than atrial blood cannot flow to vents • This is isovolumetric relaxation • Vent pressures drop, event atrial pressure is higher, the AV valves open

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