PowerPoint ® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM 18 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Heart PART 1

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Heart  A muscular double pump  Pulmonary circuit – takes blood to and from the lungs  Systemic circuit – vessels transport blood to and from body tissues  Atria – receive blood from the pulmonary and systemic circuits  Ventricles – the pumping chambers of the heart

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Pulmonary and Systemic Circuits Figure 18.1

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Location and Orientation within the Thorax  Heart – typically weighs 250–350 grams (healthy heart)  Largest organ of the mediastinum  Located between the lungs  Apex lies to the left of the midline  Base is the broad posterior surface

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Location and Orientation within the Thorax Figure 18.2

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Four “Corners” of the Heart  Superior right  At costal cartilage of third rib and sternum  Inferior right  At costal cartilage of sixth rib lateral to the sternum  Superior left  At costal cartilage of second rib lateral to the sternum  Inferior left  Lies in the fifth intercostal space at the midclavicular line

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Location and Orientation within the Thorax Figure 18.2

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Structure of the Heart – Coverings  Pericardium – two primary layers  Fibrous pericardium  Strong layer of dense connective tissue  Serous pericardium  Formed from two layers  Parietal pericardium  Visceral pericardium

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Structure of the Heart – Coverings Figure 18.3

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Structure of the Heart – Layers of the Heart Wall  Epicardium  Visceral layer of the serous pericardium  Myocardium  Consists of cardiac muscle  Muscle arranged in circular and spiral patterns  Endocardium  Endothelium resting on a layer of connective tissue  Lines the internal walls of the heart

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Structure of the Heart – Layers of the Heart Wall Figure 18.4

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings PLAY Rotatable Heart Heart Chambers  Right and left atria  Superior chambers  Right and left ventricles  Inferior chambers  Internal divisions  Interventricular septa  Interatrial septa  External markings  Coronary sulcus  Anterior interventricular sulcus  posterior interventricular sulcus

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Heart Chambers Figure 18.5b

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Right Atrium  Forms right border of heart  Receives blood from systemic circuit  Pectinate muscles  Ridges inside anterior of right atrium  Crista terminalis  Landmark used to locate veins entering right atrium  Fossa ovalis  Depression in interatrial septum  Remnant of foramen ovale

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Right Ventricle  Receives blood from right atrium through the tricuspid valve  Pumps blood into pulmonary circuit via  Pulmonary trunk  Internal walls of right ventricle  Trabeculae carneae  Papillary muscles  Chordae tendineae

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Left Atrium  Makes up heart’s posterior surface  Receives oxygen-rich blood from lungs  Opens into the left ventricle through  Mitral valve (left atrioventricular valve)

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Left Ventricle  Forms apex of the heart  Internal walls of left ventricle  Trabeculae carneae  Papillary muscles  Chordae tendineae  Pumps blood through systemic circuit via  Aortic semilunar valve (aortic valve) PLAY Rotatable Heart Section

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Heart Chambers Figure 18.5e

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Inferior View of the Heart Figure 18.5d

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Pathway of Blood Through the Heart  Beginning with oxygen-poor blood in the superior and inferior venae cavae  Go through pulmonary and systemic circuits  A blood drop passes through all structures sequentially  Atria contract together  Ventricles contract together

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Blood Flow Through the Heart Figure 18.6

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Pathway of Blood Through the Heart Figure 18.6b

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Heartbeat  70 – 80 beats per minute at rest  Systole – contraction of a heart chamber  Diastole – expansion of a heart chamber  Systole and diastole also refer to  Stage of heartbeat when ventricles contract and expand

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Structure of Heart Wall  Walls differ in thickness  Atria – thin walls  Ventricles – thick walls  Systemic circuit  Longer than pulmonary circuit  Offers greater resistance to blood flow

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Structure of Heart Wall  Left ventricle – three times thicker than right  Exerts more pumping force  Flattens right ventricle into a crescent shape Figure 18.7