Functional Anatomy of the Heart and Heart Sounds PDF

Functional Anatomy of the Heart and Heart Sounds  The Heart Functional Anatomy Four muscular chambers and four passive pressure-cycled valves Functionally divided into right heart and left heart Right heart receives the mixed venous bl...

Functional Anatomy of the Heart and Heart Sounds  The Heart Functional Anatomy Four muscular chambers and four passive pressure-cycled valves Functionally divided into right heart and left heart Right heart receives the mixed venous blood and pumps into pulmonary artery Left heart receives oxygenated blood through pulmonary vein and pumps into aorta Left ventricular walls are the thickest and generates much higher-pressure during contraction  Heart Champers Right atrium receives blood from the veins Right ventricle passes the blood on to the pulmonary artery to the lungs Left atrium receives oxygen-rich blood from the lungs and pumps to the left ventricle. Left ventricle pumps the oxygen- rich blood to the body through a large network of arteries. 3  Heart Valves A series of four valves Tricuspid valve Regulates flow of blood right atrium to the right ventricle. Pulmonary valve Regulates blood flow from the right ventricle to the pulmonary artery. Mitral valve Allows blood to move from the left atrium to the left ventricle. Aortic valve Allows blood to move from the left ventricle to the aorta 4  Tissue components of heart Cardiomyocyte Contracts and generates force Pacemaker tissue and conductive components SA node, AV node, Bundle of his and its branches, Purkinje fibers Generates rhythm and conducts it to various parts. Fibro collagenous components Fibrous skeleton Structural support, anchorage for valves and electrical insulation Nervous tissue Intrinsic cardiac ganglia and interconnecting neurons Regulation of cardiac activity  Heart muscles The heart has specific muscles that cause the heart to contract and open and close the heart values. Some of these muscles are: TrabeculaeCarneae Irregular muscles of the ventricles Chordae Tendineae Small cords that connect the heart values to the papillary muscles  Heart Sounds The listening of heart sounds with the help of a stethoscope is called Auscultation. Lub (first heart sound) which is associated with the closure of the AV valves. Dub (second heart sound) which is associated with the closure of the semilunar valves.  Auscultatory Areas on the Chest Wall 1. Aortic area Right 2nd intercostal space along the sternal border. 2. Pulmonary area Left 2nd intercostal space along the sternal border. 3. Mitral area Left 5th intercostal space, 1cm medial to mid-clavicular line. 4. Tricuspid area 4th intercostal space at left sternal border.  First heart sound (S1), ‘lub’, is caused by Normal heart sound closure of the mitral and tricuspid valves at the onset of ventricular systole. It is best heard at the apex. Second heart sound (S2), ‘dup’, is caused by closure of the pulmonary and aortic valves at the end of ventricular systole and is best heard at the left sternal edge. It is louder and higher-pitched than the S1 ‘lup’, and the aortic component is normally louder than the pulmonary one.  Production of Heart Sounds Sounds produced as a result of vibrations in the wall of ventricles & large vessels, due to closure of valves, and turbulence in blood flow. Normally the valves on the left side of the heart close first. Valves of the right side open first. Thickness of chest wall affects the intensity of heart sounds.  First Heart Sound Long, soft & low pitched. Frequency is 30-50 cycles/sec. Duration is about 0.14 sec. Vibrations due to closure of AV valves which occur at the beginning of ventricular systole cause its production.  Second Heart Sound Short, sharp & high pitched. Frequency is 50-200 cycles/sec. Duration is 0.11 sec. Major cause of its production is vibrations due to closure of semilunar valves which occur at the beginning of isovolumic relaxation phase, at the beginning of ventricular diastole. Vibrations in the walls of ventricles & large vessels when blood is ejected may be the Minor cause of its production.  Other heart sounds The 3rd heart sound: is the heard in the mid diastole due to the blood that fills the ventricles. The 4th heart sound: also known as atrial heart sound. It occur when the atrium contracts & pumps blood to the ventricles. It is almost never heard by the stethoscope.