LAYERS OF THE HEART WALL FIBROUS SKELETON MYOCARDIUM

LAYERS OF THE HEART WALL FIBROUS SKELETON MYOCARDIUM VALVES Dr. Andrea D. Székely Semmelweis University Department of Anatomy, Histology and Embryology

CIRULATION OVERVIEW Size of a Fist 250 – 350 grams Double Pump Oxygenated and deoxygenated blood Pulmonary circuit Systemic Circuit

LOCATION OF THE HEART Posterior to the Sternum Within the Mediastinum Apex vs. Base

TOPOGRAPHY

INTERNAL FEATURES

THE WALL OF THE HEART Epicardium = visceral Pericardium (serosa) Myocardium: muscle tissue + c. t. + blood vessels + nerves Endocardium: simple squamous epithelium + c. t. - continuous with the intima of vessels

EPICARDIUM = visceral pericardium lamina visceralis pericardii serosi · covers the subepicardiac adipose tissue (surrounding the vessels) · flattens the sulci on the surface to prevent friction · reflections PARIETAL PERICARDIUM = fibrous + serous layers • Pericardium fibrosum - collagen + elastic fibrous net , connects to mediastinal pleura, sternopericardiac ligg. and the respiratory system · Pericardium serosum - simple squamous epith, 2 laminae, between them lies the pericardiac cavity (serous surface - frictionless gliding, sliding) · Lamina visceralis (pericardii serosi) = Epicardium · Lamina parietalis - lining of the Pericardium fibrosum

MYOCARDIUM Striated, aerobic, interwoven, autorrhythmic Intercalated discs - gap junctions, strong desmosomes Functional syncytium (UNIT = CELL) May undergo hypertrophy Myocardiac infarct - more frequent LEFT SIDE toxic necrosis - more frequent RIGHT SIDE

LAYERS OF VENTRICULAR MYOCARDIUM EXTERNAL (E) MIDDLE (M) INNER (I) ANULUS FIBROSUS M M I E The 3 layered structure is more prominent in the left ventricle M I E

LAYERS OF VENTRICULAR MYOCARDIUM EXTERNAL MIDDLE INTERNAL

ENDOCARDIUM simple squamous epithelium + c. t. - continuous with the intima of vessels

ENDOCARDIUM Covers papillary muscles, trabeculae carneae chordae tendineae LAYERS Single layer of endothelial cells (will take up a cuboidal shape during systole) Basement membrane (loose CT) Subendocardiac CT (connects with the myocardium, contains elastic nets and branching smooth muscle cells to follow the volume changes) Branches of the conducting system NO BLOOD VESSELS

THE TRUE FIBROUS RINGS

BLOOD FLOW PATTERN THROUGH THE HEART 1. 2. 3. 4. 5. 6. RIGHT ATRIUM via the superior and inferior venae cavae TRICUSPID VALVE into right ventricle PULMONARY SEMILUNAR VALVES into pulmonary trunk and to the lung PULMONARY VEINS into the left atrium BICUSPID VALVE into left ventricle AORTIC SEMILUNAR VALVES into aorta

VALVES OF THE HEART 1. 4 SETS OF VALVES PREVENT BACKFLOW OF BLOOD = Mitral valve POSTERIOR RIGHT P P S A A P B J J ANTERIOR LEFT B A Close passively under blood pressure Heart sounds produced by valve closure

ATRIOVENTRICULAR VALVES BICUSPID vs TRICUSPID valves are restrained by chordae tendinae which are in turn attached to papillary muscles (prevention of backflow!)

SEMILUNAR VALVES AORTIC vs PULMONARY AORTA Valvula posterior Valvula sinistra Valvula dextra Lunula Nodulus Pars densa

DEVELOPMENT OF VALVES

AUSCULTATION POINTS OF HEART SOUNDS 1 st HS: at beginning of ventricular contraction, due to closure of the AV valves 2 nd HS: at beginning of ventricular diastole, due to closure of the semilunar valves

AORTIC STENOSIS PATHOLOGY Poststenotic dilation in the aorta (arrow). Hypertrophy of the left ventricle. NORMAL

OPEN HEART SURGERY

ARTIFICIAL AORTIC VALVES

MITRAL VALVE PROLAPSE Most common cardiac variation (5 -10% of population) Mitral valve cusps do not close properly Regurgitation during left ventricular systole Not life threatening; may be lifestyle threatening