Advanced Biology

1. Advanced Biology Heart

2. Size, Shape, Location • Fist • Hollow, cone shaped • Mediastinum, Rests on diaphragm, posterior to sternum, Lungs on each side

3. Size, Shape, Location • 2/3 lie to left of midsternal line • Points toward right shoulder and left hip (apex, PMI)

5. Structure/Function 4 Chambers • 2 Superior Atria • 2 Inferior Ventricles • Divided by interatrial/interventricular septum

6. Structure/Function 4 Chambers • Most Mass in Right and Left Ventricles; pumping chambers • Right= Forms most of the anterior surface • Left= Forms inferoposterior aspect. Much more muscular!

7. Structure/Function 4 Chambers • Posterior Atrial walls are smooth • Anterior Atrial walls are rigid with bundles of muscle tissue • Atria are the Receiving chambers; thin walled

8. Pathway of Blood • Blood Flow through chambers • Right Atrium – Superior Vena Cava, Inferior Vena Cava, Coronary Sinus • Left Atrium – 4 Pulmonary veins pump blood back

9. Pathway of Blood • Right Ventricle – pumps blood to pulmonary trunk (goes to lungs) • Left Ventricle – pumps blood to Aorta, then out to body

10. Pathway of Blood • Valves – Atrioventricular (AV) • Right – Tricuspid • Left – Bicuspid • Semilunar valves in pulmonary trunk/aorta

11. Pathway of Blood • Pulmonary Circuit – Pulmonary veins have blood with oxygen • Pulmonary arteries have blood without oxygen

12. Pathway of Blood • Systemic Circuit – Arteries have blood with oxygen • Veins have blood without oxygen • See page 662

14. Major Branches • Coronary Circulation – supply blood to the heart • Left Coronary – runs to left side and divides into two parts

15. Major Branches • Anterior Interventricular artery • Supplies blood to interventricular septum and anterior walls of ventricles

16. Major Branches • Circumflex artery • Supplies blood to the left atrium and posterior wall of left ventricle

17. Major Branches • Right Coronary – Runs to the right and also divides into two parts

18. Major Branches • Marginal Artery – lateral part of right side of heart (atrium) • Posterior interventricular artery – Runs to the apex, supplies posterior ventricle walls

19. Major Branches • Cardiac Veins – 1 major, 3 minor that dump into • Coronary Sinus – empties blood into the right atrium. • Located on Posterior side

20. Major Branches • Great Cardiac Vein – Found in the anterior interventricular sulcus (groove) • Middle Cardiac Vein – In posterior interventricular sulcus

21. Major Branches • Small Cardiac Vein – runs along heart’s right inferior margin • Several other anterior cardiac veins empty directly into Right Atrium

24. Problems? • Myocardial Infarction (MI) – Heart Attack. • Blockage to coronary arteries reduces blood flow • Damage to the Left Ventricle is the most serious

26. Conduction System • Intrinsic Cardiac Conduction System – Non-contractile cells that initiate and distribute impulses

27. Conduction System • Sinoatrial Node (SA) – In right atria • Heart’s Natural Pacemaker • Atrioventricular Node (AV) – In interatrial septum above tricuspid valve

28. Conduction System • Atrioventricular Bundle (bundle of His) – electrical connection between atria and ventricle • Bundle Branches – Run down interventricular septum to apex

29. Conduction System • Purkinje Fibers – penetrate apex, run superiorly up ventricle walls • Like milking a cow

31. ECG • Electrocardiograph • Waves include • P – SA node sends first impulse

32. ECG • QRS – Ventricular depolarization • Precedes ventricular contraction • T – Ventricular Repolarization

33. ECG • Intervals • P-R (P-Q) – Beginning of atrial excitation and ventricular contraction • Q-T – Action potential through Heart

35. Cardiac Cycle • Systole – Contraction of ventricles or atria • Diastole – Relaxation of ventricles or atria

36. Cardiac Cycle • Systolic Pressure – Ventricular contraction 120mmHg • Diastolic Pressure – Ventricular refilling 80mmHg • Hypertension – High BP • Hypotension – Low BP

37. Heart Sounds • Lub-dup • Lub – AV valves close (systole) • Dup – SL valves close (diastole)

38. Heart Sounds • Murmurs – obstructions in BV • Thin walled vibrations

39. Cardiac Output • CO = amount of blood pumped by each ventricle in 1 minute • CO = HR x SV (stroke volume) • SV = Volume of blood pumped out by ventricle (Force of contraction)

40. Cardiac Output • CO = 75 bpm x 70mLpb • CO = 5250 mL/min

41. Developmental Aspects • Heart pumps by 23rd day • 1-2 days later, chambers start to form • Chambers are:

42. Developmental Aspects • Sinus venosus – receives all venous blood, becomes Rt. Atrium & Coronary Sinus, SA node • Atrium – becomes muscle ridged parts of atrium

43. Developmental Aspects • Ventricle – Becomes left ventricle • Bulbus cordis – Gives rise to the pulmonary trunk, first part of the aorta, most of the right ventricle

44. Age Related Changes • Sclerosis – Thickening of valve flaps • Decline in Cardiac Reserve – Heart is less able to adjust to changes

45. Age Related Changes • Fibrosis of cardiac muscle – Scarred nodes, increase in arrhythmias • Atherosclerosis – acclerated by inactivity, smoking, stress. CV disease