University:
Kentucky State University
Course:
BIO 301 | Human Anatomy
Academic year:

2019
Views:

177

Pages:

28
Author:

omiliar74be

The Cardiovascular System The Heart and Blood Vessels  The Cardiovascular system is formed of three components: Blood, Heart and the Blood Vessels  Blood is a liquid connective tissue that carries nutrients to the various parts of the body and removes waste product  Blood is carried by tube-like structures called blood Vessels  The Heart pumps the blood into these vessels with sufficient force to make it reach all parts of body 1 The Heart  A hollow pyramidal shaped muscular organ located within the pericardium in the middle mediastinum in the thoracic cavity The heart features:  3 surfaces (anterior, inferior and posterior)  4 borders (right, inferior, left and superior)  4 chambers (right and left atria and ventricles)  Apex. 6 7 The Pericardium Membrane (fibroserous) surrounding and protecting the heart and roots of large blood vessels Main parts 1. Outer Fibrous pericardium 2. Inner Serous pericardium 8 Surfaces of the heart Anterior Surface:  Formed by the: Right atrium Right ventricle Left ventricle  Related to the sternum Posterior Surface:  Formed by the: Left atrium  Related to the esophagus -------------------------------------------Inferior Surface:  Formed by the: Right ventricle Left ventricle  It’s the surface upon which the heart rests on the diaphragm Borders of the heart They’re very important to know to understand X-rays of the heart 1. Left border: Left auricle and left ventricle 2. Inferior border: Left ventricle, right ventricle and right atrium 3. Right border: Right atrium 4. Superior border: The great vessels 11 Apex of the heart  Formed by the left ventricle  Directed downwards, forwards and to the left  Located at the left 5th intercostal space 9cm from the midline  Can be felt by palpation 12 Layers of the heart wall 1. Epicardium (external layer)  Visceral layer of serous pericardium  Covered by mesothelium  Contains fat and coronary vessels 2. Myocardium  95% of heart is cardiac muscle 3. Endocardium (inner layer)  Lined by endothelium 13 14 Chambers of the heart  2 atria – receiving chambers    Auricles increase capacity 2 ventricles – pumping chambers Sulci – grooves  1. 2. Contain coronary blood vessels Atrioventricular groove (Coronary sulcus) Interventricular sulcus (Anterior and Posterior) 15 16 The Right Atrium (RA)    Receives blood from 1. Superior vena cava. No valve is present 2. Inferior vena cava. A non-functioning valve guards its opening 3. Coronary sinus. Drains most of the blood from the heart. A non-functioning valve guards its opening 4. Small heart veins Interatrial septum has fossa ovalis  Remnant of foramen ovale Blood passes through the right atrioventricular orifice (which’s guarded by the tricuspid valve) into right ventricle 17 18 The Right Ventricle (RV)     Trabeculae carneae – ridges formed by raised bundles of cardiac muscle fiber Cusps of the tricuspid valve are connected to chordae tendinae which are connected to papillary muscles Interventricular septum Blood leaves through pulmonary orifice which’s guarded by the pulmonary semilunar valve (3 semilunar cusps) into pulmonary trunk and then right and left pulmonary arteries 19 20 The Left Atrium (LA)    About the same thickness as right atrium Receives blood from the lungs through pulmonary veins (4) no valves Blood Passes through the left atrioventricular orifice into the left ventricle. This orifice is guarded by the bicuspid/ mitral valve 21 The Left Ventricle (LV)      Thickest chamber of the heart Forms apex The cusps of the mitral valve are attached to chordae tendinae which are attached to papillary muscles Blood passes through aortic orifice into the aorta. This orifice is guarded by the aortic semilunar valve (3 semilunar cusps) Some blood flows from the aorta into coronary arteries, remainder to body 22 23 Valves Of The Heart Ensure one way flow through the heart  Atrioventricular Valves      between the atria & the ventricles right side - tricuspid value left - bicuspid or mitral valve chordae tendineae to papillary muscles Semilunar Valves     at the beginning of the arteries that leave the heart 3 cusps per valve pulmonary semilunar valve aortic semilunar valve Myocardial thickness Atrial walls are thinnest Right ventricle thinner than left ventricle      pumps blood shorter distance Left ventricle walls are thickest Right and left ventricles pump same volume of blood with each beat 25 26 The Fibrous Skeleton of the heart  Dense connective tissue that forms a base for the valves, point of insertion for muscle bundles, and electrical insulator between atria and ventricles 27 The Conducting System of the heart      Formed of specialized cardiac muscle fibers Self-excitable Repeatedly generate action potentials that trigger heart contractions Nerve impulses from autonomic nervous system (ANS) and hormones modify timing and strength of each heartbeat but do not establish fundamental rhythm 2 important functions of these specialized cells 1. Act as pacemaker 2. Form heart conducting system arrhythmias 28 Conduction Pathway 1. Begins in sinoatrial (SA) node in right atrial wall  Propagates through atria via gap junctions  Atria contract 2. Reaches atrioventricular (AV) node in interatrial septum 3. Enters atrioventricular (AV) bundle (Bundle of His)  Only site where action potentials can conduct from atria to ventricles due to fibrous skeleton 4. Enters right and left bundle branches which extends through interventricular septum toward apex 5. Finally, large diameter Purkinje fibers conduct action potential to remainder of ventricular myocardium  Ventricles contract 29 Frontal plane Left atrium Right Right atrium atrium 1 SINOATRIAL (SA) NODE 2 ATRIOVENTRICULAR (AV) NODE 3 ATRIOVENTRICULAR (AV) BUNDLE (BUNDLE OF HIS) Left ventricle 4 RIGHT AND LEFT BUNDLE BRANCHES Right Right ventricle ventricle Anterior view of frontal section 30 The Coronary Circulation      Myocardium has its own network of blood vessels Coronary arteries branch from ascending aorta  Anastomoses provide alternate routes or collateral circuits  Allows heart muscle to receive sufficient oxygen even if an artery is partially blocked Left Coronary Artery  Anterior Interventricular and Circumflex branches Right Coronary Artery  Marginal and Posterior Interventricular branches Coronary veins  All venous blood collects into Coronary Sinus which opens into RA (on posterior aspect of heart atrioventricular groove) 31 32

The Heart

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