BSC2086 A P II Final Exam Study Guide Lesson 7 8 Lesson 7 8 The Heart The Cardiovascular System lungs Pulmonary Circuit Carries blood to and from gas exchange surfaces of the Systemic Circuit Carries blood to and from the rest of the body o Performed by the right side of the heart o Contains oxygen poor blodo o Performed by the left side of the heart o Contains oxygen rich blood Blood alternates between pulmonary circuit systemic circuit Three 3 Types of Blood Vessels o Arteries Carry blood away from the heart o Veins Carry blood to the heart o Capillaries Networks between arteries and veins Location where dissolved gases nutrients and waste products are exchanged between blood and tissue Anatomy of the Heart Four 4 Chambers of the Heart o Right Atrium Collects blood from systemic circuit o Right Ventricle Pumps blood to pulmonary circuit o Left Atrium Collects blood from pulmonary circuit o Left Ventricle Pumps blood to systemic circuit Heart Involuntary muscular pump located in the thoracic cavity o Typical adult heart 5 inches from base to apex pointed tip points to left side of body o Great veins and arteries located at the base o Surrounded by pericardial sac 1 BSC2086 A P II Final Exam Study Guide Lesson 7 8 o Sits in the mediastinum region between two pleural cavities Pericardium Double lining of pericardial cavity o Visceral Pericardium Inner layer of pericardium o Parietal Pericardium Outer layer that forms the inner layer of pericardial sac fibrous tissue that surrounds and stabilizes heart Pericardial Cavity o Between parietal and visceral layers o Contains pericardial fluid secreted by the pericardial membranes Lubricates prevents friction o Pericarditis Infection of pericardium causing inflammation Superficial Anatomy of the Heart Atria Thin walled upper chambers of the heart Sulci Grooves that separate the chambers o Coronary Sulcus Divides atria and ventricles o Interventricular Sulcus Separate left and right ventricles Contains blood vessels of cardiac muscle 2 BSC2086 A P II Final Exam Study Guide Lesson 7 8 Heart wall consists of o Epicardium outer layer Visceral pericardium that covers the heart o Myocardium middle layer Muscular wall of the heart Consists of Concentric layers of cardiac muscle tissue Atrial myocardium wraps around great vessels Two divisions of ventricular myocardium o Endocardium inner layer of epithelium Endothelium lines surfaces of chambers 3 BSC2086 A P II Final Exam Study Guide Lesson 7 8 Cardiac Muscle Tissue Involuntary cardiac muscle connected by intercalated discs o Intercalated Discs Desmosomes tightly link cells together Convey force of contraction Gap Junctions link cytoplasm of cells together Propagate action potentials 4 BSC2086 A P II Final Exam Study Guide Lesson 7 8 Characteristics of Cardiac Muscle Cells o Small size o Single central nucleus o Branching interconnections between cells o Intercalated discs 5 BSC2086 A P II Final Exam Study Guide Lesson 7 8 Interatrial Septum Separates atria Interventricular Septum Separates ventricles Atrioventricular AV Valves Folds of fibrous tissue that extend into openings between atria and ventricles o Connect right atrium to right ventricle left atrium to left ventricle o Permit blood flow from atria to ventricles in one direction Right Atrium o Superior Vena Cava Receives blood from head neck upper limbs and chest o Inferior Vena Cava Receives blood from trunk viscera and lower limbs o Coronary Sinus Opens into right atrium returns blood from cardiac veins o Foramen Ovale An opening through interatrial septum found before birth Connects the two atria Seals off at birth forming the fossa ovalis shallow depression Right Ventricle ventricle o Free edges attach to chordae tendineae by papillary muscles of Prevent AV valve from opening backward Muscles tense before ventricle contracts o Right Atrioventricular AV Valve Tricuspid Valve Has three 3 cusps Allows blood flow from right atrium to right ventricle Prevents backflow Pulmonary Circuit 6 BSC2086 A P II Final Exam Study Guide Lesson 7 8 o Right ventricle pushes blood to pulmonary trunk through the pulmonary semilunar valve Pulmonary valve has three semilunar cusps o Pulmonary trunk divides into left and right pulmonary arteries leads to the left and right lungs Left Atrium o Blood from the lungs gathers into left right pulmonary veins o Pulmonary veins deliver blood to left atrium o Blood from left atrium passes to left ventricle through left atrioventricular AV valve two cusped valve known as the bicuspid or mitral valve Left Ventricle o Holds same volume as right ventricle o Larger muscle is thicker and more powerful o Systemic Circulation Blood leaves left ventricle through aortic semilunar valve into ascending aorta Ascending aorta turns aortic arch and becomes descending aorta Right Ventricle Wall is thinner develops less pressure Pouch shaped Damage death of cells is survivable contraction of left ventricle also squeezes right ventricle to push blood into the lungs Left Ventricle Wall is thicker develops more pressure Round Damage is more serious Heart Valves Two pairs of one way valves prevent backflow during contraction o Atrioventricular AV Valves Between atria ventricles Blood pressure closes valve cusps during ventricular contraction Papillary muscles tense chordae tendineae to prevent valves from swinging into atria o Semilunar Valves Pulmonary aortic tricuspid valves Prevent backflow from pulmonary trunk and aorta into ventricles Have NO muscular support no papillary muscles Three cusps support like tripod The Conducting System Heartbeat A single contraction of the heart o Entire heart contracts in series First atria then the ventricles Two 2 Types of Cardiac Muscle Cells o Conducting Cells Control coordinate heartbeat o Contractile Cells Produce contractions that propel blood Cardiac Cycle 7 BSC2086 A P II Final Exam Study Guide Lesson 7 8 o Begins with action potential from pacemaker cells at the sinoatrial SA node Transmitted through conducting system Produces action potentials in cardiac muscle cells contractile cells Action potentials electrical events can be recorded by an electrocardiogram ECG or EKG Conducting System A system of specialized cardiac muscle cells Initiates distributes electrical impulses that stimulate contraction o o Since they initiate the impulses they show automaticity Automaticity Cardiac muscle tissue contracts automatically Does NOT require nervous or endocrine output o Structures of the
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