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The Heart

19. The Heart. I. Circuits and Chambers. The heart is a muscular double pump A. Pulmonary circuit : Right side receives oxygen-poor blood from the body and pumps it to the lungs B. Systemic circuit : Left side receives oxygenated blood from lungs and pumps throughout the body

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The Heart

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  1. 19 The Heart

  2. I. Circuits and Chambers The heart is a muscular double pump A. Pulmonary circuit: Right side receives oxygen-poor blood from the body and pumps it to the lungs B. Systemic circuit: Left side receives oxygenated blood from lungs and pumps throughout the body Atria = Receive blood from the pulmonary and systemic circuit Ventricles = Pump blood to the pulmonary and systemic circuit

  3. Pulmonary Circuit Aorta andbranches Pulmonaryarteries Left atrium Pulmonaryveins Right atrium Heart Right ventricle Left ventricle Systemic Circuit Venaecavae Oxygen-rich,CO2-poor blood Oxygen-poor,CO2-rich blood

  4. II. Location and Orientation within the Thorax A. Healthy heart typically weighs 250–350 grams B. Largest organ of the mediastinum - located between the lungs C. Apex lies to the left of the midline D. Base is the broad posterior surface E. The Four “Corners” ► Superior right - at costal cartilage of third rib and sternum ► Inferior right - at costal cartilage of sixth rib lateral to sternum ► Superior left - at costal cartilage of second rib lateral to sternum ► Inferior left - lies in the fifth intercostal space

  5. Superiorvena cava Midsternal line Aorta Rib 2 Parietalpleura (cut) Diaphragm Pulmonarytrunk Left lung Pericardium(cut) Mediastinum Apex ofheart Heart Diaphragm Right lung T8 Posterior Mediastinum Aorta Superiorvena cava Left lung Fat inepicardium Right auricleof right atrium Rib 5 Pericardium(cut) Rightventricle Apex of heart

  6. III. Membranes of the Heart Pericardium - two primary layers A. fibrouspericardium - strong layer of dense connective tissue B. serous pericardium – reduces friction as heart beats 1. parietal layer = attached to the “wall” of cavity 2. visceral layer = attached to the heart surface (“organ”)

  7. Pulmonarytrunk Fibrous pericardium Parietal layer of serouspericardium Pericardium Pericardial cavity Myocardium Epicardium (viscerallayer of serouspericardium) Heartwall Myocardium Endocardium Heart chamber

  8. IV. Layers of the Heart Wall A. Epicardium - visceral layer of the serous pericardium (“upon”) B. Myocardium - consists of cardiac muscle 1. cardiac muscle arranged in circular and spiral patterns C. Endocardium – inner surface 1. endothelium resting on a layer of connective tissue 2. lines the internal walls of the heart 3. Continuous with endothelium of arteries and veins

  9. Cardiacmusclebundles

  10. V. Heart Chambers A. Right and left atria - superior chambers B. Right and left ventricles - inferior chambers C. Internal divisions – septum wall between chambers 1. interventricular septa 2. interatrial septa

  11. Auricle ofleft atrium Right atrium Left ventricle Right ventricle Apex Anterior view

  12. VI. Right Atrium A. Forms right border of heart B. Receives oxygen-poor blood from systemic circuit through: 1. superior vena cava 2. inferior vena cava 3. coronary sinus (blood returning from veins of heart itself) C. Pectinate muscles - ridges inside anterior of right atrium D. Fossa ovalis - depression in interatrial septum 1. remnant of foramen ovale – hole between atria in fetal heart

  13. VII. Right Ventricle A. Receives blood from right atrium through the right atrioventricular valve (tricuspid valve) B. Pumps blood into pulmonary circuit through pulmonary trunk C. Features of the internal walls of right ventricle ► trabeculae carneae – “fishnet like” small cavities ► chordae tendineae – “strings” attached to the valve cusps ► papillary muscles – attached to the chordae ► pectinate muscle – normal “smooth-like” muscle of walls D. Pulmonary semilunar valve (pulmonary valve) 1. Located at opening of right ventricle and pulmonary trunk

  14. VIII. Left Atrium A. Forms the apex of the heart B. Makes up heart’s posterior surface C. Receives oxygen-rich blood from lungs through pulmonary veins D. Opens into the left ventricle through 1. left atrioventricular valve (bicuspid valve) a. mitral valve is another name for the left AV valve E. Pumps blood through systemic circuit via 1. aortic semilunar valve (aortic valve)

  15. Brachiocephalic trunk Superior vena cava Right pulmonary artery Ascending aorta Pulmonary trunk Right pulmonary veins Right atrium Right ventricle Inferior vena cava Anterior view

  16. Anterior view

  17. Left common carotid artery Left subclavian artery Aortic arch Left pulmonary artery Left pulmonary veins Auricle ofleft atrium Left ventricle Apex Anterior view

  18. Anterior view

  19. Right atrium Fossa ovalis Pectinate muscles Tricuspid valve Right ventricle Chordae tendineae Trabeculae carneae Frontal section

  20. Frontal section

  21. Left atrium Left pulmonary veins Mitral (bicuspid) valve Aortic valve Pulmonary valve Left ventricle Papillary muscle Interventricular septum Frontal section

  22. Frontal section

  23. Right atrium Auricle of left atrium Left atrium Left ventricle Right ventricle Apex Inferior view; surface shown rests on the diaphragm.

  24. IX. Heart Valves—Valve Structure A. Atrioventricular (AV) valves 1. between atria and ventricles Right AV valve tricuspid valve Left AV valve bicuspid (mitral) valve B. Aortic and pulmonary valves 1. at junction of ventricles and great arteries

  25. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Mitral(left atrioventricular)valve Tricuspid(right atrioventricular)valve Aorticvalve Pulmonaryvalve Anterior

  26. Direction ofblood flow Atrium Cusp ofatrioventricularvalve (open) Chordaetendineae Papillarymuscle Ventricle

  27. X. Pathway of Blood Through the Heart superior/inferior vena cavae► right atrium ► (tricsupid valve) ► right ventricle ► (pulmonary semilunar valve) ► pulmonary trunk ► LUNGS ► pulmonary veins ► left atrium ► (bicuspid (mitral) valve) ► left ventricle ► (aortic semilunar valve) ► aorta ► BODY

  28. XI. Structure of Heart Wall A. Walls differ in thickness 1. atria = thin walls; ventricles = thick walls 2. left ventricle 3X thicker than right ventricle a. exerts more pumping force (to the body!!) Left venticle

  29. XII. Conduction System of the Heart A. Cardiac muscle cells have intrinsic ability to: 1. generate and conduct impulses 2. signal these cells to contract rhythmically SA node ► AV node ► AV Bundle (Bundle of His) ► Bundle branches ► Purkinje fibers

  30. Right atrium sinoatrial (SA)node (pacemaker cells) atrioventricular(AV) node Left atrium atrioventricular(AV) bundle Inter-ventricularseptum bundle branches Purkinje fibers

  31. Right atrium Left atrium Inter-ventricularseptum

  32. XIII. Innervation of the Heart A. Parasympathetic fibers 1. branches of vagus nerve (X) 2. decrease heart rate 3. restricted to: SA node, AV node, coronary arteries B. Sympathetic nerves 1. travel from cervical and upper thoracic chain ganglia 2. also SA node, AV node, coronary arteries 3. also innervate cardiac muscle throughout the heart a. increase heart rate and strength of contraction

  33. Dorsal motor nucleusof vagus The vagus nerve(parasympathetic)decreases heart rate. Cardioinhibitorycenter Cardioacceleratorycenter Medulla oblongata Sympathetictrunkganglion Thoracic spinal cord Sympathetic trunk Sympathetic cardiacnerves increase heart rateand force of contraction. AVnode SAnode Parasympathetic fibers Sympathetic fibers Interneurons

  34. XIV. Blood Supply to the Heart A. Coronary arteries 1. right coronary artery ► branches to form the marginal artery ► later branches into the posterior interventricular artery 2. left coronary artery ► anterior interventricular artery and circumflex artery

  35. XV. Cardiac Veins A. carry deoxygenated blood from the heart wall to the right atrium B. occupy sulci (grooves) on the heart’s surface C. Coronary sinus—runs in the posterior part of the coronary sulcus 1. Returns majority of venous blood from heart to the right atrium D. Three tributaries of coronary sinus ► great cardiac vein ► middle cardiac vein ► small cardiac vein

  36. Superiorvena cava Aorta Pulmonary trunk Anastomosis(junction ofvessels) Left atrium Left coronaryartery Right atrium Rightcoronaryartery Circumflex artery Left ventricle Right ventricle Anterior interventricular artery Rightmarginalartery Posterior interventricular artery The major coronary arteries Superiorvena cava Great cardiac vein Anteriorcardiacveins Coronary sinus Small cardiac vein Middle cardiac vein The major cardiac veins

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