Cardiovascular System

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School

University of New South Wales *

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Course

1521

Subject

Medicine

Date

Oct 30, 2023

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docx

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Cardiovascular System  Know the plan of the circulatory system, including the systemic and pulmonary circulation. The heart is a transport system consisting of two side-by-side pumps. o Right side receives oxygen-poor blood from tissues.  Pumps blood to lungs to get rid of CO2, pick up O2, via PULMONARY CIRCULATION o Left side receives oxygenated blood from lungs.  Pumps blood to body tissues via SYSTEMIC CIRCULATION Receiving chambers of the heart: o Right atrium - receives blood returning from SYSTEMIC CIRCULATION o Left atrium - receives blood returning from PULMONARY CIRCULATION Pumping chambers of the heart: o Right ventricle - pumps blood through PULMONARY CIRCULATION o Left ventricle - pumps blood through SYSTEMIC CIRCULATION  Describe the orientation, location and surface anatomy of the heart in the thorax. Size: approximately the size of a fist and weighs less than 400 grams. Location: o In mediastinum between second rib and fifth intercostal space. o On superior surface of diaphragm. o Two-thirds of heart to left of midsternal line. o Anterior to vertebral column, posterior to sternum. Base (posterior surface) - leans toward right shoulder. Apex - points toward left hip Apical impulse - palpated between fifth and sixth ribs, just below left nipple. Coverings of the heart: o Pericardium: double-walled sac that surrounds heart; made up of two layers o Superficial fibrous pericardium: functions to protect, anchor heart to surrounding structures, and prevent overfilling o Deep two-layered serous pericardium  Parietal layer lines internal surface of fibrous pericardium

 Visceral layer (epicardium) on external surface of heart  Two layers separated by fluid-filled pericardial cavity (decreases friction) Layers of the Heart wall: o Epicardium - visceral layer of serous pericardium. o Myocardium - circular or spiral bundles of contractile cardiac muscle cells.  Anchors cardiac muscle fibers.  Supports great vessels and valves.  Limits spread of action potentials to specific paths. o Endocardium - innermost layer; is continuous with endothelial lining of blood vessels.  Lines heart chambers and covers cardiac skeleton of valves. Chambers and Associated Great Vessels: Internal Features: o There are four chambers, two superior atria and two inferior ventricles . o Interatrial septum: this separates the atria. The fossa ovalis is the remnant of foramen ovale of fetal heart. o Interventricular septum: separates ventricles. Surface Features: o Coronary sulcus (atrioventricular groove): encircles junction of atria and ventricles. o Anterior interventricular sulcus: anterior position of interventricular septum. o Posterior interventricular sulcus : Landmark on posteroinferior surface. o Identify chambers and valves of the heart and understand how they function. Atria: the receiving chambers. o Small, thin-walled chambers that contribute little to propulsion of blood. o Auricles: appendages that increase atrial volume. o Right Atrium: Receives deoxygenated blood from the body  Anterior portion is smooth-walled.

 Posterior portion contains ridges formed by pectinate muscles. Pectinate muscles can only be found in the auricle.  Posterior and anterior regions are separated by crista terminalis.  Three veins empty into right atrium:  Superior vena cava: returns blood from body regions above the diaphragm.  Inferior vena cava: returns blood from body regions below the diaphragm.  Coronary sinus: returns blood from coronary veins. o Left Atrium: receives oxygenated blood from lungs.  Pectinate muscles found only in auricles.  Four pulmonary veins return blood from lungs. Ventricles: the discharging chambers. o Makes up the majority of the volume of the heart. o Right Ventricle: most of anterior surface. o Left Ventricle: posteroinferior surface. o Trabeculae Carneae: irregular ridges of muscle on ventricular walls. o Papillary Muscles: project into ventricular cavity.  Anchor chordae tendineae that are attached to heart valves. o They have thicker walls than atria. o Actual pumps of heart. o Right ventricle pumps blood into pulmonary trunk. o Left ventricle pumps blood into aorta which is the largest artery in the body. o Right ventricle is thicker than left ventricle, this is because the right ventricle needs a stronger muscle to pump the blood the the rest of the body. Heart Valves. o Ensure unidirectional blood flow through heart. o Open and close in response to pressure changes. o There are two major types of valves:  Atrioventricular valves located between atria and ventricles.  Semilunar valves located between ventricles and major arteries. o No valves are found between major veins and atria.

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