The Heart


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The Heart

  2. 2. POSITION OF THE HEART The muscular pump that is located between lungs, slightly to the left of the breastbone.
  3. 3. SIZE OF HEART Slightly larger than a human fist. Weight of between 200 to 425grams Heart is beating approximately 100,000 times everyday
  4. 4. Anatomy of the heart Has 4 chambers Upper chamber – called atria ( left and right) Lower chamber – called ventricle (left and right) All 4 chambers are separated by wall of muscle known as the septum
  5. 5. Chamber of the heart
  6. 6. Wall of the heart Pericardium – the outer layer – the thin serous membrane comprising the outer surface of the heart. Myocardium – middle layer – muscular wall of the heart. This thickest middle layer of the heart is composed of cardiac muscle tissue Endocardium – inner layer – smooth inner surface of the heart chambers and the valves
  7. 7. RIGHT ATRIUM Receives blood from the body via superior and inferior vena cava. Highly distensible chamber - accommodate the VR and maintain a low pressure ( 0 – 3 mmHg) The actual pressure depends upon the volume of the blood within the right atrium. Blood flows down into the right ventricle across the tricuspid valve.
  8. 8. Right ventricle (RV) Is smaller because it only has to transmit blood a short distance to the lungs. The free wall is not as thick as the left ventricle Blood flow out to the lungs via semilunar pulmonic valve through the pulmonary artery
  9. 9. Left atrium (LA) Blood returns to the heart from the lungs via 4 pulmonary veins that enter the LA LA is highly compliant like a RA - LA pressure is higher than RA (6 -10 mmHg) Blood flows out into the LV across the mitral valve.
  10. 10. Left Ventricle (LV) Left ventricle (LV) is the largest chamber and has a very thick muscular wall (it can generate high pressures during contraction, as they have to force blood flow through the aortic valve into the body) Blood from the LV is ejected across the aortic valve into the aorta then to the rest of the body and other organs.
  11. 11. How does blood travel through the heart? SVC RA RV PULMONARY ARTERY LUNGS ( GAS EXCHANGE)
  12. 12. How does blood travel through the heart? Lungs Pulmonary Veins LA LV Aorta Organs Rest of the body
  13. 13. Blood flow through the heart
  14. 14. Valves of the heart Tricuspid valve Pulmonary valve Mitral valve Aortic valve
  15. 15. Tricuspid valve Also called atrioventricular or AV valves Situated between the RA and RV Has 3 leaflets with fibrous strands (chordae tendineae) on their leaflets that attach to papillary muscles located on the respective ventricular walls Prevents the backflow of blood from the RV
  16. 16. Mitral valve Also called bicuspid valve Between the LA and LV Consist of 2 leaflets Prevents the backflow of blood into LA from the LV
  17. 17. Pulmonary valve Situated between right ventricle and the pulmonary artery that leads to the lungs Has 3 leaflets It prevents the backflow of blood into the right ventricle from the pulmonary circulation
  18. 18. Aortic valve Placed between the LV and the aorta It consist of 3 semicicular leaflets. Prevent backflow of blood from the aorta once it has left the heart
  19. 19. The papillary muscles contract during ventricular contraction and generate tension on the valve leaflets via the chordae tendineae to prevent the AV valves from bulging back into the atria and becoming incompetent
  20. 20. Blood supply to the heart Heart muscle needs more oxygen than any organ except the brain , therefore the heart must have generous supply of blood The flow of blood that supplies the heart tissue itself is the coronary circulation Blood is supplied to the heart by coronary artery – left and right
  21. 21. Coronary artery
  22. 22. Right coronary artery Right marginal branch – supply blood to the lateral wall of the RV Posterior interventricular artery -- within the posterior interventricular sulcus . – supply blood to the ventricles posteriorly It also supply blood - 55% to SA node - 90% to AV node - a portion of Bundle of His
  23. 23. Left coronary artery Begins behind the left cusp of the aortic semilunar valve and devide into 2 branch 1 – anterior interventricular branch which decends in the anterior interventricular sulcus ( LAD). -- supply blood to the ventricles anteriorly 2 – a circumflex branch which continous in the coronary sulcus (LCx ) -- supply blood to most of the posterior wall of the heart
  24. 24. Left Anterior Descending Supply blood to : Anterior 2/3 of septum Right bundle branch Anterosuperior division of the left bundle Anterior wall of the left ventricle
  25. 25. Left circumflex SA node (45%) Posteroinferior division of left bundle ( a portion) Lateral wall of the LV
  26. 26. Conduction system of the heart Consist of modified cardiac muscle cells 2 nodes that play fundamental parts in this conduction system
  27. 27. Conduction system Sino – atrial (SA) node – located in the posterior wall of right atrium – also known as the pacemaker -- a stimulus arising from the SAnode cause atrial to contract ( impulse from SA node travel to the AV node)
  28. 28. Conduction system Atrioventricular (AV ) node -- found in the inferior part of the interatrial septum. -- It acts as a relay station
  29. 29. Conduction system Then impulse passes through bundle of His ( atrioventricular bundle) , it is located in the interventricular septum and devides to form the right and left bundle branches. Impulse then generate through Purkinje fibres which form the branching of right and left bundle branches at the apex of the heart. Its function is to stimulate the ventricles to contract
  30. 30. Conduction system of the heart
  31. 31. Thank you