Lecture 10 Cardiology

1. Lecture 10 Cardiology

2. ___________ is the study of the heart and its diseases • The heart is located in the space between the lungs known as the ___________. • The heart may be regarded as a double pump and thus circulates blood in ______ circulations - the _________ and the ______.

3. Location: • w/i mediastinum – oblique orientation – • 2nd rib  5th intercostal space • 2/3 mass to left of mid-sternal line • Base = posterior surface • Apex: points forward towards left hip • Auscultation: point of maximum between 5th + 6th ribs

5. About ________ of the mass of the heart is to the _________ of the midline. • A mid-sagital section through the mediastinum would leave ______ of the mass of the heart in the left section. • The apex of the heart is at the height of the _____ rib.

6. Coverings – pericardium • Fibrous pericardium – collagen reinforced loose fitting sac • Lined internally by parietal pericardium – serous membrane • Attaches to major vessels and diaphragm • Visceral pericardium • Adheres directly to surface of heart • = epicardium – outermost layer of heart wall • Pericardial cavity – • pericardiatis

8. The double layered serous membrane structure which encloses the heart is the __________. • The layer of this membrane which lies directly against the muscle of the heart is known as the _____________ • The most superficial layer of the loose fitting sac about the heart is the __________ • The space between the inner and outer membranes filled with ________ is known as the _________

9. Wall of Heart: • Epicardium = _____________ • Myocardium = • Interlaced bundles of _______________ • Reinforced internally by Fibrous Skeleton of Heart • Insertion for _______________ _____________ • Thickenings support blood vessels + valves • Directs spread of electrical signal w/i myocardium • Endocardium: endothelium – tissue type? • Smooth & continuous lining with blood vessels exiting heart

11. Cardiac Muscle – Forms Myocardium • Fibers: short/fat/branched/interconnected • 1-2 nuclei • Surrounded by endomysium – loose connective tissue • Numerous blood vessels • Forms ??? • Numerous mitochondria – 25-35% volume of cells • Intercalated discs: physical/electrical connection • Gap junctions allow passage of ions • Desmosomes – • anchor cells together - Anchor point for myofibrils • Acts as functional syncytium– electrically coupled

13. External Features: Apex Base Sulci Auricle(s) Ventricles Pulmonary trunk Ascending aorta Superior vena cava Auricle of right atrium Ligmentum arteriosum Brachiocephalic trunk Left common carotid Left subclavian artery right left

14. External Features: • Auricle of right atrium • Left ventricle • Posterior interventricular sulcus • Left atrium • Inferior and superior vena cava • Coronory sinus • Right and Left pulmonary arteries • Aorta • Right atrium

15. Atria • Ventricles • Valves + features • Tricuspid • Bicuspid • Semilunar • Fossa ovale • Trabeculae carneae

16. Internal Structure of Heart - Atria • Thin walled - superior • Receive blood from systemic/pulmonary circulation • Pump blood to ventricles • Auricles – allow addition capacity • Valves prevent back-flow • Tricuspid : right • Bicuspid or mitral: left • Right: • Pectinate muscles • Fossa ovalis – remnant of foramen ovale in interatrial septum • Left: • Smooth walled • Forms most of the base of the heart • Receives blood from lungs - 4 pulmonary veins (2 right + 2 left)

17. Internal Structure of Heart – Right Ventricle • Relatively light walled – pumps blood to pulmonary circuit • Forms most of anterior surface of heart • Squeezes blood against interventricular septum • Moderator band • Contains conducting fibers • Trabeculae carneae • papillary muscles • Cone shaped • Conus arteriosus at superior end terminates at pulmonary semi lunar valve

18. Internal Structure of Heart – Left Ventricle • Heavy walled – pumps blood to systemic circuit • Round in x-section • Contracts longitid. and in diameter • No Moderator band • Prominent trabeculae carneae • 2 large papillary muscles • Blood enters aorta • Aortic semi lunar valve • Aortic sinus behind cusps

21. Valves - Atrioventricular • Right: Tricuspid • Left: Mitral or Bicuspid • Valve components: • Ring of supporting connective tissue • Connective tissue cusps – covered with endocardium • Cordae tendineae • Papillary muscles • Contract prior to other ventricular musculature • Prevent prolapse of valve cusps

22. The valves prevent backflow of blood Pulmonary valve Aortic valve Tricuspid valve Bicuspid (mitral valve)

23. Semilunar Valves • Aortic • Aortic sinus – • exit point for cardiac circulation • Prevent sticking of cusps to walls of aorta • Pulmonary • In pulmonary trunk • No valves to prevent back-flow from atria • Minimal back-flow does occur • Myocardium compresses around opening to vessels

24. Valve Operation and Sounds • Opening and closure due to pressure difference • Lubb • Closure of AV valves • Dubb • Closure of semi lunar valves • Ascultation • Listening – diagnostic for valve defects

25. AuscultationNormal Heart vs. Abnormal Heart (Mitral Valve Prolapse) Lub-dub - normal Chug-a-lug – prolapsed mitral valve

26. Conduction System of Heart Autorhythmic Cells Cells fire spontaneously, act as pacemaker and form conduction system for the heart SA node cluster of autorhythmic cells in wall of Rt. Atria begins heart activity that spreads to both atria excitation spreads to AV node AV node in atrial septum, transmits signal to bundle of His AV bundle of His the connection between atria and ventricles divides into bundle branches & purkinje fibers, large diameter fibers that conduct signals quickly

27. The apex of the heart is which chamber? • Pectinate muscles are found in which chamber? • The fossa ovalis is found in the _________ • Blood passing from the left atrium to the left ventricle passes what valve? • Blood entering the right atrium does so from what vessels?

28. Internal Conduction System • Sinoatrial node (SA, pacemaker). • Atrioventricular node (AV). • Atrioventricular bundle. • Right and left bundle branches • Purkinje Fibers.

29. Heart Rate • SA node establishes basic contraction rate • Modified by nervous/hormonal input • Acetylcholine slows from SA rate • Norepinephrine speeds • Resting rate: ~70-80 contractions/min • Bradycardia: abnormally slow heart rate • Trachycardia: rapid heart rate

30. Intrinsic heart rate established by SA node • Modified by extrinsic impulses from cardiac centers in medulla • Cardioacceleratory centers  sympathetic spinal nerves • Cardioinhibitory center  parasympathetic dorsal vagus nucleus  via vagus nerve

31. Impulses that slow heart rate arise in the _______________ of the _________ • Impulses that speed heart rate arrive at the heart in the cardiac nerve and are part of the ____________ nervous system.

32. Path of blood flow • Blood enters right atria from • Systemic circulation – inferior and inferior vc • Cardiac circulation – via cardiac sinus • Atrial systole – blood moves into right ventricle past tricuspid valve • Ventricular systole (atrial diastole): blood flows into pulmonary trunk – pulmonary semilunar valves  pulmonary circulation • Enters left atrium: • Atrial systole: enters left ventricle past bicuspid valve • Left ventricle to aorta – aortic semilunar valves • Fetal circulation differs

33. Electrocardiogram---ECG or EKG • EKG • Action potentials of all active cells can be detected and recorded • P wave • atrial depolarization • P to Q interval • conduction time from atrial to ventricular excitation • QRS complex • ventricular depolarization • T wave • ventricular repolarization

34. Cardiac Cycle

35. Coronary Circulation: • Left coronary artery & Right coronary artery • Branch off aorta above aortic semilunar valve • First vessels leaving aorta • Right Coronary  • Atrial branches to right atrium • Ventricular branches to right ventricle and interventricular septum • Conducting system • Left Coronary  • Left atrium/ ventricle • Patterns may vary with individual – anastomoses form

36. Coronary Veins • Collects wastes from cardiac muscle • Drains into a large sinus on posterior surface of heart called the coronary sinus • Coronary sinus empties into right atrium

37. Coronary Artery Disease • Heart muscle receiving insufficient blood supply • narrowing of vessels---atherosclerosis, artery spasm or clot • atherosclerosis--smooth muscle & fatty deposits in walls of arteries • Treatment • drugs, bypass graft, angioplasty, stent

38. Lung Bypasses in Fetal Circulation Ductus arteriosus is shortcut from pulmonary trunk to aorta bypassing the lungs. Foramen ovale is shortcut from right atria to left atria bypassing the lungs.