Cardiovascular System and Heart Anatomy PDF

The Cardiovascular System: The Heart Anatomy Paria SHOJAOLSADATI, assistant professor in human anatomy Istanbul Okan University School of Medicine Department of Anatomy 1 Heart Anatomy Comparable to the size of a closed fist. ▪ Location ▪ Superior surface of diaphragm ▪ 1/3 of it located at the righ...

The Cardiovascular System: The Heart Anatomy Paria SHOJAOLSADATI, assistant professor in human anatomy Istanbul Okan University School of Medicine Department of Anatomy 1 Heart Anatomy Comparable to the size of a closed fist. ▪ Location ▪ Superior surface of diaphragm ▪ 1/3 of it located at the right side of the midline and 2/3 Left of the midline ▪ Anterior to the vertebral column, posterior to the sternum 2 Heart Anatomy 3 The heart is pyramidal in shape ▪ Apex (directed to the left, anterior and inferior) ▪ Formed by the left ventricle ▪ Lies posterior to the left 5.intercostal space (app. 9 cm lateral to the midline) Th 45: Arcus aortae Bifurcatio trachea Mediastinum sup.-inf. The Place of the Heart in the Body MEDIASTINUM The heart is located in the mediastinum medium between the two lungs within the thorax cavity. Right pleural cavity Left pleural cavity superior mediastinum anterior mediastinum posterior mediastinum Middle mediastinum ▪ Has four surfaces ▪ Base (posterior surface) ▪ Anterior surface ▪ Diaphragmatic surface (inferior surface) – rests on the central tendon of the diapghragm ▪ Pulmonary surface (left and right surface) The heart has 4 surface and 4 border Right border Left border superior border inferior border sternocostal surface base of heart Left pulmonary surface Right pulmonary surface Apex of the heart Diaphragmatic surface Coverings of the Heart: Anatomy ▪ Pericardium – a double-walled sac around the heart composed of: 1. A superficial fibrous pericardium 2. A deep two-layer serous pericardium a. The parietal layer lines the internal surface of the fibrous pericardium b. The visceral layer or epicardium lines the surface of the heart ▪ They are separated by the fluid-filled pericardial cavity 12 Pericardium Pericardium Serous pericardium Visceral layer (epicardium) Parietal layer Pericardial cavity Fibrous pericardium Coverings of the Heart ▪ The Function of the Pericardium: ▪ Protects the heart ▪ Prevents overfilling of the heart with blood ▪ Allows for the heart to work in a relatively friction-free environment Chapter 18, Cardiovascular System 15 Pericardial Layers of the Heart 16 Chapter 18, Cardiovascular System 17 Heart Wall layers ▪ Epicardium – visceral layer of the serous pericardium ▪ Myocardium – cardiac muscle layer forming the bulk of the heart ▪ Endocardium – endothelial layer of the inner myocardial surface 18 Organization of Heart Wall The heart has four chambers and four valves Right atria Left atria Right ventricule Left ventricule Right atrioventricular valve ( tricuspid valve) Left atrioventricular valve (bicuspid or mitral valve) Pulmonary valve Aortic valve 20 Atria of the Heart ▪ Atria are the receiving chambers of the heart ▪ Each atrium has a protruding auricle ▪ Pectinate muscles mark atrial walls ▪ Blood enters right atria from superior and inferior venae cavae and coronary sinus ▪ Blood enters left atria from pulmonary veins Chapter 18, Cardiovascular System 22 Ventricles of the Heart ▪ Ventricles are the discharging chambers of the heart ▪ Papillary muscles and trabeculae carneae muscles mark ventricular walls ▪ Right ventricle pumps blood into the pulmonary trunk ▪ Left ventricle pumps blood into the aorta Chapter 18, Cardiovascular System 23 Gross Anatomy of Heart: Frontal Section Chapter 18, Cardiovascular System Figure 18.4e 24 Myocardial Thickness and Function Thickness of myocardium varies according to the function of the chamber Atria are thin walled, deliver blood to adjacent ventricles Ventricle walls are much thicker and stronger ▪ right ventricle supplies blood to the lungs (little flow resistance) ▪ left ventricle wall is the thickest to supply systemic circulation 25 Comparison of right and left ventricule wall thickness Chapter 18, Cardiovascular System 26 Thickness of Cardiac Walls Myocardium of the left ventricle is much thicker than the right. 27 Heart Valves ▪ Heart valves ensure unidirectional blood flow through the heart ▪ Atrioventricular (AV) valves lie between the atria and the ventricles ▪ AV valves prevent backflow into the atria when ventricles contract ▪ Chordae tendineae anchor AV valves to papillary muscles Chapter 18, Cardiovascular System 28 Heart Valves ▪ Semilunar valves prevent backflow of blood into the ventricles ▪ Aortic semilunar valve lies between the left ventricle and the aorta ▪ Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk 29 Heart Valves 30 Chapter 18, Cardiovascular System 31 Heart Valves Chapter 18, Cardiovascular System Figure3218.8c, d Atrioventricular Valve Function Chapter 18, Cardiovascular System Figure 18.9 33 Semilunar Valve Function Chapter 18, Cardiovascular System Figure 18.10 34 Right atrium The openings of SVC and ICV Surface is rough and have the pectinate muscles) Opening of the coronary sinus – lies between the orifice of IVC and left atrioventricular orifice (coronary sinus drains the cardiac veins) Interatrial septum bears the oval fossa – remnant of oval foramen and its valve Right atria Right ventricule Trabecula carnea – elevations of the cardiac muscles on the interior suface of the ventricles Tricuspid valve – has three cusps Tendinous cords – attach to the free edges of the cusps and prevent their prolaps into the right atrium during ventricular systole Papillary muscles Other ends of the tendinous cords attach to these muscles Right ventricule (continued) Interventricular septum Pulmonary valve – has three semilunar cusps – Anterior, right and left semilunar cusps – Prevents regurgitation of the blood from the pulmonary trunk back to the right ventricle Right ventricle 39 Left atrium Muscular wall is thicker in comparison to the right atrium Internal surface is smooth surface is rough and have the pectinate muscles) Four pulmonary veins open into this chamber – they don’t have any valves at their openings Chapter 18, Cardiovascular System 41 Left ventricle Muscular wall is considerably thicker in comparison to the right ventricle Mitral valve (bicupid valve)– has two cusps Papillary muscles Trabecula carnea - elevations of the cardiac muscles Aortic valve – has three cusps 43 External Heart: Vessels that Supply/Drain the Heart (Anterior View) ▪ Arteries – right and left coronary ▪ Veins – small cardiac, middle cardiac, and great cardiac veins Chapter 18, Cardiovascular System 44 Coronary Circulation: Arterial Supply 45 Coronary Circulation: Venous Supply 46 External Heart: Major Vessels of the Heart ▪ Vessels returning blood to the heart named az a vein include: 1. Superior and inferior venae cavae 2. Right and left pulmonary veins ▪ Vessels conveying blood away from the heart named az a artery include: 1. Pulmonary trunk, which splits into right and left pulmonary arteries 2. Aorta 47 External Heart: Anterior View Chapter 18, Cardiovascular System Figure 18.4b 48 External Heart: Posterior View Chapter 18, Cardiovascular System 49 Figure 18.4d Atrial Septal Defect ▪ Incomplete closure of the oval foramen ▪ Causes blood to pass from the left atrium to the right atrium ▪ This leads to the enlargement of the right atrium and ventricle, and dilatation of the pulmonary trunk 50 Ventricular Septal Defect Causes blood to pass from the left ventricle to the right ventricle (left to right shunt) A large shunt increases the outflow of the pulmonary trunk and may lead to cardiac failure 51 Pathway of Blood Through the Heart and Lungs ▪ Right atrium 🡪 tricuspid valve 🡪 right ventricle ▪ Right ventricle 🡪 pulmonary semilunar valve 🡪 pulmonary arteries 🡪 lungs ▪ Lungs 🡪 pulmonary veins 🡪 ▪ Left atrium 🡪 ▪ Left ventricle 🡪 ▪ Aorta 🡪 left atrium bicuspid valve 🡪 left ventricle aortic semilunar valve 🡪 aorta systemic circulation Chapter 18, Cardiovascular System 52 Blood Flow Through the Heart 53 Circulatory Routes ▪ Systemic Circulation: Blood flow from the L ventricle to the body & back to the R atrium. ▪ Pulmonary Circulation: Blood flow from the R ventricle to the lungs and back to the L atrium. Pathway of Blood Through the Heart and Lungs Chapter 18, Cardiovascular System Figure 18.5 55 Cardiac Muscle Contraction ▪ Heart muscle: ▪ Is stimulated by nerves and is self-excitable (automaticity) ▪ Contracts as a unit ▪ Cardiac muscle contraction is similar to skeletal muscle contraction 56 Heart conduction system ▪ Sinoatrial (SA) node generates impulses about 75 times/minute ▪ Atrioventricular (AV) node delays the impulse approximately 0.1 second 57 Heart conduction system ▪ Impulse passes from atria to ventricles via the atrioventricular bundle (bundle of His) ▪ AV bundle splits into two pathways in the interventricular septum (bundle branches) 1. Bundle branches carry the impulse toward the apex of the heart 2. Purkinje fibers carry the impulse to the heart apex and ventricular walls Chapter 18, Cardiovascular System 58 Heart Physiology: Sequence of Excitation Chapter 18, Cardiovascular System 59 Figure 18.14a Heart Excitation Related to ECG Chapter 18, Cardiovascular System Figure 18.17 60 Heart Sounds ▪ Heart sounds (lub-dup) are associated with closing of heart valves ▪ First sound occurs as AV valves close and signifies beginning of systole (contraction) ▪ Second sound occurs when SL valves close at the beginning of ventricular diastole (relaxation) Chapter 18, Cardiovascular System 61 Auscultatory Sites There are four important areas used for listening to heart sounds. These are: Aortic area, Pulmonic area, Tricuspid area, Mitral Area (Apex). Chapter 18, Cardiovascular System 62 Chapter 18, Cardiovascular System 63 Heart valve locations and auscultation (listening) sites. Chapter 18, Cardiovascular System 64 Autonomic innervation of the heart ▪ The heart is innervated by the autonomic nervous system. This innervation consists of sympathetic and parasympathetic components, collectively referred to as the coronary plexus. ▪ The innervation by autonomic centers in the brainstem doesn’t initiate a heartbeat, but it can increase or decrease the rate of the heartbeat. 65 66 Innervation of the Heart Parasympathetic effect Decreases heart rate. Diminishes blood pumping force of the heart. Constricts coronary arteries. Sympathetic effect Increases heart rate. Strengthens blood pumping force of the heart. Dilates coronary arteries. 67