The Cardiovascular System: The Heart

1. The Cardiovascular System:The Heart

2. The Heart • Cardiovascular system • heart, arteries, veins and capillaries • 2 major divisions: • 1. Pulmonary circuit - right side of heart • carries deoxygenated blood to lungs • 2. Systemic circuit - left side of heart • supplies oxygenated blood to the body • Cardiology- study of the heart

3. Cardiovascular System Circuit

4. Size, Shape and Position • Big a a closed fist, males have bigger anatomical hearts • Located in the mediastinum, like a cone on its side between the lungs • Base - broad superior portion of heart • Apex - inferior end, tilts to the left, tapers to point

5. Pericardium • Pericardium- surrounds heart, keeps your heart in it’s place (like a father-in-law with the gun collection) • Allows heart to beat without friction, room to expand and resists excessive expansion • Two layers: • Fibrous- superficial • protects, prevents overstretching, anchors heart • Serous- deep • Pericarditis= inflammation of pericardium • Cardiac Tamponade= fluid in the pericardium compressing the heart, can stop the heart beat

6. Heart Wall • 3 layers of the Heart wall • 1.) Epicardium- outside slippery layer • Also called the visceral pericardium (just to be confusing) • 2.) Myocardium- muscle of heart • 3.) Endocardium- inside the heart, covers chambers and heart valves

7. Parietal pericardium Pericardium & Heart Wall

8. Heart Chambers • 4 chambers • Right and left atria (= entry halls) • 2 superior, posterior chambers • receive blood returning to heart • Right and left ventricles (= little bellies) • 2 inferior chambers • pump blood into arteries • Left ventricle is thicker, why?

9. Anterior Anatomy – Atrioventricular sulcus - separates atria, ventriclesAnterior and posterior interventicular sulci - grooves separate ventricles Atrioventricular sulcus

10. Posterior Heart AnatomyPosterior Interventricular Sulcus- groove separating ventricles

11. Heart Chambers - Internal • Interatrial septum • wall that separates atria • Pectinate muscles • internal ridges of myocardium in right atrium and both auricles • Interventricular septum • wall that separates ventricles • Trabeculae carneae • internal ridges in both ventricles walls • Chordae tendineae- cords connecting to the tricuspid and mitral valves

12. Internal Anatomy Anterior Aspect

13. Heart Valves • Ensure one-way blood flow • Semilunar valves - control flow into great arteries • pulmonary: from right ventricle into pulmonary trunk • aortic: from left ventricle into aorta • Atrioventricular (AV) valves • right AV valve has 3 cusps (tricuspid valve) rat • left AV valve has 2 cusps (mitral,bicuspid valve) lamb • chordae tendineae - cords connect AV valves to papillary muscles (on floor of ventricles)

15. Heart Valves

16. Valve Anatomy • The AV valves, the tricuspid and bicuspid (mitral) valves

17. AV Valve Mechanics • Ventricles relax, pressure drops, semilunar valves close, AV valves open, blood flows from atria to ventricles • Ventricles contract, AV valves close(papillary m. contract and pull on chordae tendineae to prevent prolapse),pressure rises, semilunar valves open, blood flows into great vessels

18. Operation of Atrioventricular Valves

19. Operation of Semilunar Valves

20. FLOW: Right Atrium- Right Ventricle- Lungs (1-6 figure 19.9) • Blood is pumped into the right atrium (1) • Blood passes through the tricuspid (= three points) valves (2) into the right ventricle (3) • Remember: tRIcuspid is on the RIght side of the heart • The blood goes through the pulmonary semilunar (4) valves into the pulmonary trunk (5) • The pulmonary trunk divides into right and left pulmonary arteries which go to the right and left lung (6)

21. FLOW: Lungs- Left Atrium- Left Ventricle- Aorta- Body (7-12) • Blood flows from the lungs pulmonary veins (7) into the left atrium (8) • Through the bicuspid valve (9) to the left ventricle (10) • The left ventricle pumps blood through the aortic semilunar valve (11) into the ascending aorta (12) • Most blood passes to the body • Some blood goes to the heart through the coronary arteries

22. Blood Flow Through Heart

23. Coronary Circulation • Left coronary artery • 1. anterior interventricular artery • supplies interventricular septum + anterior walls of ventricles • 2. circumflex artery • passes around left side of heart in coronary sulcus, supplies left atrium and posterior wall of left ventricle • Right coronary artery • 1. posterior interventricular artery • supplies posterior walls of ventricles • 2. marginal artery • supplies lateral R atrium + ventricle • Remember: a heart that doesn’t work will- LAC RPM • Cornory arteries- Left Anterior Interventricular, circumflex and Right Posterior Interventricular and marginal

24. Coronary Vessels – Anterior---LAC RPM---

25. Coronary Vessels – Posterior---LAC RPM---

26. Circulation to the Heart • The heart can not get nutrients from inside • Blood vessels must supply the heart muscle this is called the coronary circulation • The arteries of the heart encircle it like a crown • While contacted no blood flows to the heart • When the heart relaxes the blood flows to it • FLOW- Aorta to coronary arteries to coronary veins

27. Robotic Surgery • With traditional heart surgery the patient would face two months of recovery with no lifting. • With robotic heart surgery you can return to normal activities in one week. • Robotic surgery is more precise than the human hand because it corrects for the surgeon’s tremors.

28. Structure of Cardiac Muscle • Compared to skeletal muscle cardiac muscle is: • Short in length • Branched • One to two nuclei • Has intercalated discs, these contain gap junctions that assist in electrical conduction

29. Structure of Cardiac Muscle Cell

30. Metabolism of Cardiac Muscle • Aerobic respiration • Rich in myoglobin and glycogen • Large mitochondria • Organic fuels: fatty acids, glucose, ketones • What should our diets be? • Fatigue resistant

31. Heart Electrical Conduction • Myogenic - heartbeat originates within the heart • The fundamental rhythm of the heart is automatic and not dependent on the nervous system or endocrine system • This rhythm is due to autorhythmic cells, specialized cardiac muscle fibers that are self-exciting (Thoreau cells) • These cells act as: a Pacemaker… • Setting the rhythm of the entire heart • …and Conduction system • A route for conducting electrical energy throughout the heart muscle

32. It’s All In The Timing • The chambers of the heart have to be coordinated or the heart will not work • The SA node (sinoatrial node) stimulated first, as the name implies this node causes atria contraction • Next the AV node (atrioventricular node) is stimulated • The impulse then goes to the Bundle of His (Atrioventricular bundle) • The right and left bundle branches goes to the apex of the heart • Finally, conduction myofibers termination is called Purkinje fibers that conduct impulses to the rest of the heart

33. Cardiac Conduction System

34. Cardiac Rhythm • Systole = contraction; diastole = relaxation • Sinus rhythm • set by SA node, adult at rest is 70 to 80 bpm • Ectopic foci - region of spontaneous firing (not SA) • nodal rhythm - set by AV node, 40 to 50 bpm • intrinsic ventricular rhythm - 20 to 40 bpm • Arrhythmia - abnormal cardiac rhythm • heart block: failure of conduction system • bundle branch block • total heart block (damage to AV node)

35. Heart Conduction: Memory Aid • Remember: SAVe HIS Right and Left BUN from PURKing

36. Electrocardiogram (ECG) • Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, legs and chest

37. Pacemakers • Jimmy Carter, Linus Pauling • The SA node is the pacemaker of the heart • If the SA node becomes diseased, and heart rate gets too low (<40 BPM) an Artificial Pacemaker can be surgically implanted • Other sites besides the SA node can stimulate the heart, this is called: an Ectopic pacemaker • Triggers of this activity are caffeine, nicotine, that special someone

38. EKG/ ECG • Cardiac muscle contraction is electrical, the physiology is similar to skeletal muscle (see A&PI) these electrical impulses can be detected on the skin of the chest • This recording is called an EKG (if your in the German camp) or ECG (if you are being difficult) is called an Electrocardiogram and the machine is called an Electrocardiograph • The ECG tells three things: E- electrical conduction problems in the heart, C- cardiac enlargement, G- Cardiac Damage

39. ECG Alphabet • The ECG alphabet goes PQRST • P wave- the first wave shown • QRS complex- the middle quibble • T wave- the last wave

40. Normal Electrocardiogram (ECG)

41. Electrical Activity of Myocardium QRS complex Ventricular Depolarization P wave Atrial Depolarization T wave Ventricular Repolarization

42. Waves of Meaning I • First wave= P wave- atrial DEpolarization • Second wave= QRS- ventricular depolarization as the electrical excitement spreads through the ventricles • Repolarization of the atria occurs here but is not seen due to the QRS length • Third wave= T wave- ventricular REploarization

43. ECG/EKG • Abnormal Waves • Larger P= enlarged atrium • Enlarged Q= myocardial infarction (MI= Heart attack) • Enlarged R= enlarged ventricles • Flattened T= coronary artery disease

44. EKG (ECG) • Time span between waves is called intervals or segments • P-Q interval lengthened- coronary artery disease, rheumatic fever • S-T segment elevated- Acute MI • S-T segment depressed (below baseline)- anoxia of heart muscle • Q-T interval lengthened- myocardial damage, HEART ATTACK, coronary ischemia or conduction anomalies

45. ECGs, Normal & Abnormal No P waves

46. ECGs, Abnormal Extra systole : note the inverted QRS complex, misshapen QRS and T and absence of a P wave preceding this contraction.

47. ECGs, Abnormal Arrhythmia: conduction failure at AV node No pumping action occurs

48. Cardiac Cycle • Events in one heartbeat • Systole is contraction, Diastole is relaxation (“Relax? Relax? When I die, then I’ll relax.”) • The cycle consists of systole and diastole of both atria plus systole and diastole of both ventricles

49. Heart Sounds • Listening to the sounds of the body is called auscultation (= listening), you can hear bowel sounds, breathing, and heart beats with your ear to the patient (old method) or with a stethoscope (modern method) • 4 heart sounds, 2 clinically important (because a steth can hear them): • The first sound is lubb, • First heart sound (S1), louder and longer “lubb”, occurs with closure of AV valves • The second sound is dub • Second heart sound (S2), softer and sharper “dub” occurs with closure of semilunar valves

50. Lubb- Dub • Lubb- closure of AV valves: • Tricuspid valve • Mitral valve • Dub- closure of the semilunar valves: • Aortic • Pulmonary Dub Dub Lubb Lubb