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  2. COMPONENTS OF CIRCULATORY SYSTEM • Heart • Blood vessels - arteries, veins, capillaries • Blood

  3. CIRCUITS 1. Pulmonary circuit - right side of heart • carries blood to lungs for gas exchange 2.Systemic circuit - left side of heart • supplies blood to all organs of the body


  5. THE HEART Located in the mediastinum, between the lungs Base - wide, superior portion Apex - inferior end that tilts to the left Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Aorta Pulmonary trunk Superior vena cava Base of heart Right lung Parietal pleura (cut) Pericardial sac (cut) Apex of heart Diaphragm

  6. DEFINITIONS • Epicardium - serous membrane covering heart • Myocardium - thick muscular layer of heart wall - provides attachment for cardiac muscle • Endocardium - smooth inner lining of heart wall

  7. HEART CHAMBERS • 4 chambers • Right and left atria • 2 superior chambers receive blood returning to heart • Right and left ventricles • 2 inferior chambers pump blood into arteries

  8. Interior view of the heart

  9. HEART VALVES • Ensure one-way blood flow • Atrioventricular (AV) valves • tricuspid valve - between right atrium & ventricle • mitral or bicuspid valve - between left atrium & ventricle • Chordae tendineae (tendinous cords) connect AV valves to papillary muscles on the floor of ventricles • Semilunar valves • pulmonary - at entrance to pulmonary artery • aortic - at entrance to aorta

  10. HEART VALVES Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Left AV (bicuspid) valve Right AV (tricuspid) valve Fibrous skeleton Openings to coronary arteries Aortic valve Pulmonary valve

  11. How Blood Flows Through the Heart Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 10 Blood enters right atrium from superior and inferior venae cavae. 1 2 Blood in right atrium flows through right AV valve into right ventricle. Aorta Left pulmonary artery 11 Contraction of right ventricle forces pulmonary valve open. 3 5 5 Blood flows through pulmonary valve into pulmonary trunk. 4 9 Pulmonary trunk Superior vena cava 4 Left pulmonary veins Blood is distributed by right and left pulmonary arteries to the lungs, where it unloads CO2 and loads O2. 5 6 6 Right pulmonary veins Left atrium 1 6 Blood returns from lungs via pulmonary veins to left atrium. Aortic valve 7 3 Left AV (bicuspid) valve 7 Blood in left atrium flows through left AV valve into left ventricle. Right atrium 8 Left ventricle Contraction of left ventricle (simultaneous with step 3 ) forces aortic valve open. 8 2 Right AV (tricuspid) valve 9 Blood flows through aortic valve into ascending aorta. Right ventricle 10 Blood in aorta is distributed to every organ in the body, where it unloads O2 and loads CO2. Inferior vena cava 11 11 Blood returns to heart via venae cavae.

  12. Anterior view of the heart Coronary sulcus –between atria and ventricles Interventricular sulcus - overlies the interventricular septum that separates the right and left ventricles Coronary arteries in sulci - transport oxygenated blood to the myocardium Cardiac veins in sulcidrain deoxygenated blood from the myocardium Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Ligamentum arteriosum Aortic arch Ascending aorta Superior vena cava Left pulmonary artery Branches of the right pulmonary artery Pulmonary trunk Left pulmonary veins Right pulmonary veins Left auricle Right auricle Right atrium Coronary sulcus Anterior interventricular sulcus Right ventricle Inferior vena cava Left ventricle Apex of heart

  13. Posterior view of the heart Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Aorta • The coronary • sinus in the posterior coronary • sulcus empties deoxygenated blood into the right atrium Left pulmonary artery Superior vena cava Right pulmonary artery Left pulmonary veins Right pulmonary veins Left atrium Coronary sulcus Right atrium Coronary sinus Inferior vena cava Fat Posterior interventricular sulcus Left ventricle Apex of heart Right ventricle

  14. CORONARY ARTERIES • Branches of the left coronary artery • anterior interventricular artery serves interventricular septum + anterior walls of ventricles • circumflex artery serves left atrium and posterior wall of left ventricle • Branches of the right coronary artery • marginal artery serves lateral right atrium + ventricle • posterior interventricular artery serves posterior walls of ventricles

  15. CARDIAC VEINS 1.Great cardiacvein in the anterior interventricular sulcus 2. Middle cardiacvein in the posterior interventricular sulcus 3. Coronary sinus in the posterior coronary sulcus collects deoxygenated blood and drains it mainly into right atrium - 20% venous drainage occurs directly into right ventricle & 80% returns to right atrium

  16. CARDIAC CONDUCTION SYSTEM • Sinoatrial (SA) node: pacemaker - initiates heartbeat and sets heart rate • AV node: serves as an electrical gateway to ventricles - sets heart rate is SA node is damaged • AV bundle: provides pathway for signals from AV node to apes - the right and left bundle branches enter interventricular septum and descend to apex • Purkinje fibers: conduct impulses upward from apex throughout ventricular myocardium

  17. CARDIAC CONDUCTION SYSTEM Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 SA node fires. 2 Excitation spreads through atrial myocardium. Right atrium 2 1 Sinoatrial node (pacemaker) Left atrium 3 AV node fires. 2 Purkinje fibers Excitation spreads down AV bundle. 3 4 Atrioventricular node Bundle branches Purkinje fibers distribute excitation through ventricular myocardium. Atrioventricular bundle 5 4 5 Purkinje fibers

  18. CARDIAC NERVES • Sympathetic nerves increase heart rate & blood flow • - Sympathetic nerve fibers terminate in SA node, AV node, aorta, pulmonary trunk, & coronary arteries • Parasympathetic (vagus) nerves decrease heart rate & blood flow • - Fibers of right vagus nerve innervate the SA node • - Fibers of left vagus nerve serve the AV node

  19. NOTES The heart is: • myogenic - heartbeat originates within heart • autorhythmic – regular, spontaneous depolarization occurs

  20. CARDIAC CYCLE • One complete contraction and relaxation of all 4 chambers of the heart • Atrial systole,Ventricle diastole, • Atrial diastole,Ventriclesystole • Quiescent period

  21. CARDIAC CYCLE • Quiescent period • all chambers relaxed • AV valves open • blood flowing into ventricles • Atrial systole • SA node fires, atria depolarize • atria contract, force additional blood into ventricles • ventricles now contain end-diastolic volume (EDV) of about 130 ml of blood

  22. MYOCARDIAL INFARCTION • Sudden death of heart tissue caused by interruption of blood flow from vessel narrowing or occlusion • Anastomoses defend against interruption by providing alternate blood pathways • circumflex artery and right coronary artery combine to form posterior interventricular artery • anterior and posterior interventricular arteries combine at apex of heart

  23. Coronary Atherosclerosis