BSC2086 A&P II Exam #2 Study Guide 1 Lesson 7-8: The Heart The Cardiovascular System • Pulmonary Circuit: Carries blood to and from gas exchange surfaces of the lungs o Performed by the right side of the heart o Contains oxygen poor blodo • Systemic Circuit: Carries blood to and from the rest of the body 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 sacBSC2086 A&P II Exam #2 Study Guide 2 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 • 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 chambersBSC2086 A&P II Exam #2 Study Guide 3 • 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 potentialsBSC2086 A&P II Exam #2 Study Guide 4 ! • Characteristics of Cardiac Muscle Cells: o Small size o Single, central nucleus o Branching interconnections between cells o Intercalated discsBSC2086 A&P II Exam #2 Study Guide 5 • 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 depressionBSC2086 A&P II Exam #2 Study Guide 6 • Right Ventricle o Free edges attach to chordae tendineae by papillary muscles of ventricle 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 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 CirculationBSC2086 A&P II Exam #2 Study Guide 7 Blood leaves left ventricle through aortic semilunar valve into ascending aorta Ascending aorta turns (aortic arch) and becomes descending aorta Right Ventricle Left Ventricle Wall is thinner & develops less pressure Wall is thicker & develops more pressure Pouch shaped Round Damage/death of cells is survivable – contraction of left ventricle also squeezes right ventricle to push blood into the lungs 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 • Aortic Sinuses: Sacs located at base of the ascending aorta o Are the origin of right & left coronary arteries o Prevent valve cusps from sticking to aortaBSC2086 A&P II Exam #2 Study Guide 8 !BSC2086 A&P II Exam #2 Study Guide 9 • Connective Tissue Fibers: Composed of elastic and collagen fibers o Each cell is wrapped by elastic sheath & adjacent cells wrapped by collagen fibers Physically support cardiac muscle fibers Distribute forces of contraction Add strength and prevent overexpansion of heart Provide elasticity that helps return heart
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