The Cardiovascular System The Manila Times College of Subic Prepared by: Stevens B. Badar, RN, MANc
THE HEART
Anatomy of the Heart Location and Size approx. the size of a person s fist, hollow and cone-shaped, weighing less than a pound. Enclosed in the inferior mediastinum, medial portion of the thoracic cavity. Has pointed apex that rests on the diaphragm, approx. at the level of the 5 th intercostal space. Its base or posterosuperior aspect is where great vessels of the body emerge beneath the 2 nd rib.
Coverings and Wall The heart is enclosed by a double-walled sac called PERICARDIUM.
Coverings of the Heart Pericardium/Pericardial Sac Fibrous Pericardium (outer) Serous Pericardium Parietal Pericardium Pericardial Cavity Visceral pericardium/epicardium Homeostatic Imbalance: Pericarditis (decrease serous fluid) Cardiac Tamponade (increase fluid build-up within the pericardial cavity)
Heart Walls 1. Epicardium The visceral pericardium. 2. Myocardium The layer that actually contracts. 3. Endocardium > Thin glistening sheet of endothelium that lines the heart chambers. It also continuously lines blood vessels leaving and entering the heart
Interventricular Septum Interatrial Septum Chambers and Associated Vessels Right atrium/auricle Receiving chamber Left atrium/auricle Receiving chamber Tricuspid Valve Bicuspid/Mitral Valve Right ventricle Discharging chamber Forms most of the hearts anterior surface. Left Ventricle Discharging chamber Forms the apex.
Associative Great Vessels Superior vena cava Inferior vena cava Pulmonary trunk Pulmonary artery (R/L) Pulmonary veins Aorta
Adult Circulation Pulmonary Circulation From the superior/inferior vena cava to the lungs to the aorta. Systemic Circulation From the aorta to the different parts of the body back to the SVC and IVC.
Heart valves
Heart Valves Atrioventricular Valves Tricuspid valve Bicuspid Valve/Mitral Valve Semiluna Valves Pulmonary Valve Aortic Valve Atrioventicular Valve Semilunar Valve Heart Relaxation OPEN CLOSE Ventricular Contraction CLOSE OPEN
Cardiac Circulation The system on how the myocardium are nourished. The blood supply that oxygenates and nourishes the heart is provided by the R/L Coronary artery. It branch from the base of the aorta and encircle the heart in the coronary sulcus.
Coronary arteries and their major branches Left Coronary Artery Anterior Interventricular Artery Circumflex Artery Right Coronary Artery Posterior Interventricular artery Marginal Artery
Homeostatic Imbalance Angina Pectoris severe chest pain secondary to oxygen deprivation of the myocardium. Prolong angina may cause the death of oxygen-deprived heart cells forming INFARCT. MYOCARDIAL INFARCTION is commonly called heart attack.
PHYSIOLOGY OF THE HEART
Intrinsic Conduction System of the Heart: Setting the Basic Rhythm
Cardiac Conduction (1) The sinoatrial (SA) node and the remainder of the conduction system are at rest. (2) The SA node initiates the action potential, which sweeps across the atria. (3) After reaching the atrioventricular node, there is a delay of approximately 100 ms that allows the atria to complete pumping blood before the impulse is transmitted to the atrioventricular bundle. (4) Following the delay, the impulse travels through the atrioventricular bundle and bundle branches to the Purkinje fibers, and also reaches the right papillary muscle via the moderator band. (5) The impulse spreads to the contractile fibers of the ventricle. (6) Ventricular contraction begins.
Cardiac Cycle and Heart Sounds Systole : contraction of the ventricle Diastole: relaxation of the ventricle. Cardiac Cycle : one complete heartbeat. Average heart beat approx. 75times/min. or 0.8 second per second.
Cardiac Cycle Events Mid-to-late diastole. heart in relaxation to atrial contraction to force blood to the ventricles. Ventricular systole. Ventricular contraction to entry of blood to the semilunar valves. Early diastole. Ventricular relaxation to increase pressure of the atria due to draining blood from the SVC/IVC on the right atria and draining of blood from the lungs to the Pulmonary veins to the left atria.
Cardiac Output The amount of blood pumped out by each side of the heart in 1 minute. HR x SV Stroke Volume: volume of blood pumped out by ventricle with each heart beat. It increases as the force of ventricular contraction increases.
SVC and IVC R Atrium Tricuspid Valve R Ventricle Pulmonic Valve Pulmonary Trunk R and L Pulmonary Artery Lungs R and L Pulmonary Vein L Atrium Mitral/Bicuspid Valve L Ventricle Aortic Valve Aorta Systemic Circulation SVC and IVC