1. Mediastinum Anatomy & Physiology PA 481 C Tony Serino, Ph.D. Biology Department Misericordia Univ.

2. Mediastinum Anterior Superior Middle Posterior Superior and anterior are continuous with each other; both may be referred to as the superior mediastinum

3. Superior Mediastinum Great Vessels of the Heart Aortic arch Transverse thoracic plane

4. Remnant of Ductus arteriosus Ligamentum arteriosum

5. Usual Aortic Arch Pattern 65% of all people RS BT LS LC RC

6. Aortic Arch Variations 27% one BT with both CC exiting 5% 1.2% two BT left vert. a.

7. SVC BC SVC Vagus Phrenic

8. Pulmonary Arteries and Veins

9. Trachea and Primary bronchi

10. Structure Order BC Aorta PA Trachea

11. Esophagus Function: Deglutition Two sphincters: upper and lower esophageal sphincters (lower is physiological only) Retropleural position (therefore, covered by adventitia) Mucosa: stratified squamous with many mucus glands (esophageal glands) Muscularis: changes from skeletal to smooth muscle

12. Esophagus Histology

13. Thymus Gland Bilobed organ that is largest in children, but begins to regress sharply at the onset of puberty (around age 11) It is the site of T-cell lymphocyte production and produces hormones (such as, thymosin) that modifies their physiology

14. General Circulatory System 1.Cardiovascular –Consists of a closed system of vessels which transport blood –Two circuits: Systemic and Pulmonary –Arteries move blood away from the heart –Veins move blood toward the heart

15. General Circulatory System 2.Lymphvascular – moves lymph –Consist of blind end tubes which collect interstitial fluid (now called lymph) and returns it to circulation –The lymph is cleaned before returned to the blood vessels

16. Heart Development

17. Fetal Circulation

18. Selected Heart Defects

19. Heart as a Dual Pump Cardiac muscle arranged as whorls that squeeze the blood Twin pumps: systemic and pulmonary Four chambers: 2 atria and 2 ventricles

20. Cardiac Muscle Cells

21. Cardiac Muscle Depolarization

22. Conductance of Ions during Depolarization

23. Heart: Location

24. Heart in Relation to other Organs

25. Layers of the Heart and Pericardium

26. Heart: Anterior View Transverse Pericardial sinus

27. Heart: Posterior View Oblique Pericardial sinus

28. Heart: Internal Anatomy

29. Differences in Ventricular Wall

30. Coronary Artery Schematic (LAD)

31. Most Common Coronary Arterial Pattern Fig. 1.51 Ant. Desc. a. (LAD) Post. Desc. a. R. Marginal a. L. Marginal a. Circumflex a.

32. Coronary Variation 15% LCA dominant Single CA Most people right dominant. Circumflex from right aortic sinus (4% have an accessory coronary artery) (note: which branch gives rise to posterior descending a.determines dominance)

33. Fig. 12.66b

34. Fig. 12.66c

35. Fig. 12.66d

37. Coronary Vein Schematic

38. Coronary Veins Fig. 1.52 Coronary sinus Great Cardiac v. Small Cardiac v.Middle Cardiac v. Ant. Cardiac veins

39. Major Cardiac Valves

40. aortic valve (SL) AV (tricuspid) Heart Valves sinus Nodule (corpara aranti) cusps

41. Fig. 12.07b

42. Diastole: Period of Ventricular Filling

43. Systole: Isovolumetric Contraction

44. Systole: Ventricular Ejection

45. Diastole: Isovolumetric Relaxation

46. Conduction System of Heart

47. Pacemaker Potential

49. ECG and electrical changes

50. Normal ECG

51. ECG Normal Sinus Rhythm Junctional Rhythm (AV node rhythm)

52. Second Degree Heart Block Ventricular Fibrillation (V-fib)

53. Heart Sounds “Lub-dub” Sound associated with valve closing producing turbulent blood flow

54. Cardiac Cycle

55. (ml/min)

56. Factors Affecting SV Stroke Volume (SV) = End Diastolic Volume – End Systolic Volume SV = EDV – ESV (ml/beat) EDV affected by: –Venous return which is dependent on venous tone, skeletal muscle pumps, etc. ESV –As the heart fills it is stretched which allows for better overlap of the contractile proteins which will affect the force of contraction and the ESV (Starling’s Law of the Heart) –Increasing the force of contraction at any EDV will decrease the ESV and increase the SV (sympathetic stimulation and epinephrine)

58. Sympathetic Stimulation Leads to increase HR Increases in Ca ++ release from SR, increase Ca ++ through membrane and increase myosin crossbridge cycling Increases force of contraction

59. Heart Rate Control Sinus Rhythm = normal SA node control Autonomic Activity –Sympathetic (thoracic trunk) = accelerator (induces tachycardia) –Parasympathetic (vagus n.)= brake (induces bradycardia) Hormones –epinephrine Drugs -caffeine, nicotine, atropine, etc.

60. Posterior Mediastinum Thoracic aorta Sympathetic trunk Vagus n. Azygous v. Trachea Esophagus Phrenic n. Intercostal a., v., & n. Hemiazygous v. Lung root Thoracic duct

61. Small Aortic Branches Bronchial a. Intercostals Coronary Esophageal

62. Azygous vein Hemiazygous v.

63. Nerves of Post. Mediastinum

64. Thoracic Duct