Chapter 19a- The Circulatory System: Anatomy of the Heart
Chapter 19a- The Circulatory System: Anatomy of the Heart BIOL 20214
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This 7 page Study Guide was uploaded by Marlee Porter on Wednesday February 3, 2016. The Study Guide belongs to BIOL 20214 at Texas Christian University taught by Mrs. Crenshaw in Spring 2016. Since its upload, it has received 82 views. For similar materials see Anatomy and Physiology in Biology at Texas Christian University.
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Date Created: 02/03/16
Chapter 19 The Circulatory System: Anatomy of the Heart The Heart Equal amount of blood sent to each circuit simultaneously Two Circuits: 1. Pulmonary Circuit Blood flow heart lungs heart Purpose transport CO2 to the lungs to eliminate; oxygenate blood before returning it to the heart Lowpressure vessels 2. Systemic Circuit Blood flow heart body tissues heart Purpose deliver O2 and other nutrients to body tissues for metabolism; transport wastes away from tissues Highpressure vessels External Anatomy Enclosed in the mediastinum and rests on the superior surface of the diaphragm Base uppermost end; wide and directed toward right shoulder Apex tip; points toward the left hip Apical impulse apex of heart beating against chest wall; point of maximal intensity (PMI) Enclosed by the Pericardium (Pericardial Sac) Double walled sac surround the heart Isolates the heart from the thoracic organs and allows it to expand Two Tissues: Fibrous Pericardium Superficial layer Anchors heart to surrounding structures, protects the surface and prevents overfilling Parietal Pericardium Deeper layer Lines the internal surface of the fibrous pericardium At superior margin of heart, parietal layer runs inferiorly to become the visceral pericardium Pericardial Cavity Space between Pericardium and Visceral Pericardium Filled with serous fluid to lubricate the surface of the heart Pericarditis inflammation of the pericardium; roughens serous membranes and produces large amounts of inflammatory fluids Tamponade pressure from inflammatory fluids; compresses the heart; must be removed by syringe Epicardium “upon the heart” Visceral Layer of the Serous Pericardium Includes adipose tissue Contains the largest branches of coronal blood vessels Myocardium Cardiac muscle Thickness is proportional to the workload of the chambers Reinforced by the fibrous skeleton Crisscrossing collagen and elastic fibers Provides structural support for large vessels and valves Anchors contractile cardiac muscle fibers Not electrically excitable; slows passage of electrical signals between the atria and the ventricles Endocardium Lines the inside of the heart chambers and valves Made of endothelium (squamous epithelium with underlying CT) Continuous endothelial lining of blood vessels leaving and entering the heart Endocarditis inflammation of the heart valves Caused by bacteria, fungus, or autoimmune Coronary Circulation Functional blood supply to the heart Supply the wall of the heart with nutrientrich blood, then drain the waste products generated by metabolism Anatomy varies in people Many anastomoses (junctions) of arterial vessels to provide circulation to the heart all incase of obstruction Coronary arteries First branch off the aorta At rest delivers 250 mL of blood per minute to the myocardium Arteries deliver blood to the heart when it is relaxed, but are compressed by the myocardium during contraction Left Coronary Artery Branches into: Anterior Interventricular Artery supplies blood to both ventricles and the interventricular septum Circumflex branch and the Left Marginal branch supply the left ventricle and the right atrium Right Coronary Artery Supplies the right atrium and the sinoatrial node Branches into: Right Marginal branch supplies the lateral aspect of the right atrium and right ventricle Posterior Interventricular branch supplies the posterior walls of both ventricles and the posterior portion of the interventricular septum Coronary Veins Route by which blood leaves the myocardium and returns to venous circulation Empty blood into the coronary sinus on the posterior heart Coronary sinus empties blood directly into the right atrium Venous drainage the route by which blood leaves the myocardium The Great Cardiac Vein collects blood from the anterior surface of the heart Posterior Interventricular Vein (Middle Cardiac) drains blood from the posterior surface of the heart Left Marginal Vein drains the left side of the heart These vessels empty blood into the Coronary Sinus on the posterior side Coronary Sinus empties blood directly into the Right Atrium Angina Pectoris thoracic pain caused by temporary ischemia to the myocardium May be induced by blockage in the arteries, stressinduced spasm of the arteries, or from increased contractions of the heart Deprived myocardium produces lactic acid through anaerobic fermentation, which stimulates the sensation of pain Myocardial Infarction (MI) heart attack; prolong ischemia that can cause tissue death Cardiac muscle is mostly amitotic, so damaged areas are replaced by scar tissue Can lead to arrhythmia and failure to contract, leading to heart failure or weakening of the heart wall Damage to the left ventricle is the most serious Internal Anatomy Atria receiving chambers; relatively thin; contract minimally to propel blood into underlying ventricles Right atrium receives blood from: Superior Vena Cava Inferior Vena Cava Coronary Sinus Left atrium receives blood from: 4 pulmonary veins Auricles increase atrial volume Pectinate Muscles seen in right atrium and in the auricles; ridges of myocardium Fossa Ovalis depression in the interatrial septum; remnant of the fetal Foramen Ovale Ventricles discharging chambers Trabeculae Carneae irregular ridges of muscle Papillary muscles attach Chordae Tendineae to keep atrioventricular valves from inverting during contraction Right Ventricle Contracts and sends blood to Pulmonary Trunk sends blood to lungs Left Ventricle Contracts and sends blood to the Aorta sends blood to the rest of the body Walls are thicker than the Right ventricle The ventricles are separated by the Interventricular Septum Heart Valves Four valves enforce oneway flow of blood through the heart Open and close in response to pressure differences on their two sides Atrioventricular Valve (AV Valve) Prevent backflow of blood into the atria when the ventricles contract Tricuspid Valve Right AV Valve Mitral (Bicuspid) Valve Left AV Valve Prolapse one or more flap(s) come incompetent and allow blood regurgitation Semilunar Valves guard the large arteries from ventricles and prevent backflow Pulmonary Valve Blood flow from the Right Ventricle to the pulmonary trunk Aortic valve Blood flow from the Left Ventricle to the Aorta No valves guarding the Vena Cava or Pulmonary veins
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