The Circulatory System

1. The Circulatory System Ch 18

2. Components of the Human Circulatory System The Heart Blood Vessels Blood Lymphatic Vessels Lymph

3. Functions of the Circulatory System • Transport oxygen to cells • Transport nutrients from the digestive system to body cells • Transport hormones to body cells • Transport waste from body cells to excretory organs • Distribute body heat

4. Energy Requirements: • lots of mitochondria • aerobic respiration

5. Mechanisms and events of contractions: • All or none law- at organ level, not cellular level • Means of stimulation- autorhythmicy • Length of refractory period- cardiac (250ms), skeletal (1-2ms)

6. Location of Heart Location of Heart

7. Layers of Cardiac Tissue • Visceral pericardium • Outer protective layer composed of a serous membrane • Includes blood capillaries, lymph capillaries, and nerve fibers.

8. Layers of Cardiac Tissue • Myocardium • Relatively thick. • Consists largely of cardiac muscle tissue responsible for forcing blood out of the heart chambers. • Muscle fibers are arranged in planes, separated by connective tissues that are richly supplied with blood capillaries, and nerve fibers.

9. Layers of Cardiac Tissue • Endocardium • Consists of epithelial and connective tissue that contains many elastic and collagenous fibers. • Connective tissue also contains blood vessels and some specialized cardiac muscle fibers called Purkinje fibers. • Lines all of the heart chambers and covers heart valves.

10. Pericardial Cavity

11. Layers of Cardiac Tissue

12. Heart Anatomy

13. Heart Anatomy

14. Heart Anatomy http://www.youtube.com/watch?v=tBQa8IBzP6I

15. Heart Anatomy Left ventricle Right ventricle Interventricular septum

16. Circulation

17. Mechanisms & Events of Contraction • Means of stimulation • Organ vs motor unit contraction • Length of absolute refractory period

18. Microscopic Anatomy of Cardiac Muscle • Cardiac muscle cells are striated, short, fat, branched, and interconnected • Connective tissue matrix (endomysium) connects to the fibrous skeleton • T tubules are wide but less numerous; SR is simpler than in skeletal muscle • Numerous large mitochondria (25–35% of cell volume)

19. Nucleus Intercalated discs Cardiac muscle cell Gap junctions Desmosomes (a) Figure 18.11a

20. Microscopic Anatomy of Cardiac Muscle • Intercalated discs: junctions between cells anchor cardiac cells • Desmosomes prevent cells from separating during contraction • Gap junctions allow ions to pass; electrically couple adjacent cells • Heart muscle behaves as a functional syncytium

21. Microscopic Anatomy of Cardiac Muscle

22. Microscopic Anatomy of Cardiac Muscle

23. VALVES Pulmonary valve Myocardium Aortic valve Tricuspid (right atrioventricular) valve Area of cutaway Mitral valve Tricuspid valve Mitral (left atrioventricular) valve Myocardium Tricuspid (right atrioventricular) valve Aortic valve Mitral (left atrioventricular) valve Pulmonary valve Aortic valve Pulmonary valve Aortic valve Pulmonary valve Area of cutaway (b) Fibrous skeleton Mitral valve Tricuspid valve (a) Anterior Figure 18.8a

24. VALVES Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Chordae tendineae attached to tricuspid valve flap Papillary muscle (c) Figure 18.8c

27. pulmonary arteries right atrium aorta pulmonary arteries pulmonary vein superior vena cava left atrium left ventricle inferior vena cava right ventricle

28. Heart Valves pulmonary semilunar valve aortic semilunar valve bicuspid valve tricuspid valve

29. Contraction Cycle of the Heart

30. Contraction Cycle of the Heart

31. Contraction Cycle of the Heart

32. Cardiac Output CO = the vol. of blood ejected from the l. or r. ventricle into the aorta or pulmonary trunk each min. CO= SV x HR SV= stroke vol.; the vol of blood ejected from the ventricle during each contraction (ml/beat) HR= heart rate; # beats/min, at rest ~60, exercise ~100

33. Cardiac Output (at rest) SV = 75 ml/beat HR = 75 beats/min CO = 75 ml/b x 75 b/min CO = 5250 ml/min = 5.25 L/min

34. Cardiac Output (exercise) SV = 100 ml/beat HR = 100 beats/min CO = 100 ml/b x 100 b/min CO = 10 L/min

35. Electrical Conductivity of the Heart

36. Nerve Innervation: pons Vagus nerve from medulla (parasympathetic division) acetylcholine (slows heart) Cardioacceleratory center in medulla (sympathetic)  adrenaline from adrenal glands (speeds up heart) medulla oblongata vagus

37. Electrocardiogram (ECG) 0.1 sec 0.3 sec 0.4 sec • P = atrial depolarization ~ 0.1 sec atria contracts • QRS = ventricular depolarization ventricles contract (lub), contraction stimulated by Ca++ uptake • T = ventricular repolarization ventricles relax (dub)

38. Excitation of the Heart R Depolarization SA node Repolarization T P Q S 1 Atrial depolarization, initiated bythe SA node, causes the P wave. Figure 18.17, step 1

39. R Depolarization SA node Repolarization T P Q S 1 Atrial depolarization, initiated bythe SA node, causes the P wave. R AV node T P Q S 2 With atrial depolarization complete,the impulse is delayed at the AV node. Figure 18.17, step 2

40. R Depolarization SA node Repolarization T P Q S 1 Atrial depolarization, initiated bythe SA node, causes the P wave. R AV node T P Q S 2 With atrial depolarization complete,the impulse is delayed at the AV node. R T P Q S 3 Ventricular depolarization beginsat apex, causing the QRS complex.Atrial repolarization occurs. Figure 18.17, step 3

41. Depolarization Repolarization R T P Q S 4 Ventricular depolarization iscomplete. Figure 18.17, step 4

42. Depolarization Repolarization R T P Q S 4 Ventricular depolarization iscomplete. R T P Q S 5 Ventricular repolarization beginsat apex, causing the T wave. Figure 18.17, step 5

43. Depolarization Repolarization R T P Q S 4 Ventricular depolarization iscomplete. R T P Q S 5 Ventricular repolarization beginsat apex, causing the T wave. R T P Q S 6 Ventricular repolarization iscomplete. Figure 18.17, step 6

44. (a) Normal sinus rhythm. (b) Junctional rhythm. The SA node is nonfunctional, P waves are absent, and heart is paced by the AV node at 40 - 60 beats/min. (d) Ventricular fibrillation. These chaotic, grossly irregular ECG deflections are seen in acute heart attack and electrical shock. (c) Second-degree heart block. Some P waves are not conducted through the AV node; hence more P than QRS waves are seen. In this tracing, the ratio of P waves to QRS waves is mostly 2:1. Figure 18.18

45. Heart Sounds • Two sounds (lub-dup) associated with closing of heart valves • First sound occurs as AV valves close and signifies beginning of systole • Second sound occurs when SL valves close at the beginning of ventricular diastole • Heart murmurs: abnormal heart sounds most often indicative of valve problems

46. Coronary Artery Disease(CAD) • Arteriosclerosis • HDL vs LDL

47. Homeostatic Imbalances • Angina pectoris • Thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium • Cells are weakened • Myocardial infarction (heart attack) • Prolonged coronary blockage • Areas of cell death are repaired with noncontractile scar tissue http://www.youtube.com/watch?v=l36zIKP53Ls

48. Coronary Artery Disease(CAD) Diagnosis • Stress test • Echocardiography • http://youtu.be/DuanD-z45tw • Cardiac catheterization • Coronary angiography

49. Cardiac Catheterization

50. Coronary Artery Disease(CAD) Treatment • Coronary bypass grafting (CABG) • Percutaneous transluminal coronary angioplasty (PTCA)