Seeley, Stephens and Tate Essentials of Anatomy and Physiology Fifth edition Seeley, Stephens and Tate Chapter 12: The Heart Slide 2.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Cardiovascular System A closed system: heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate A double system: Pulmonary circuit Systemic circuit Slide 11.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Cardiovascular System Functions: Delivery system for everything! Remove carbon dioxide and other waste products Slide 11.1 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart Location Size: About the same as your fist Thoracic cavity, between the lungs In mediastinum Pointed apex directed toward left hip 2/3 to left of median plane Size: About the same as your fist Slide 11.2a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Location and Orientation within the Thorax Figure 18.2

The Heart: Did You Know… A blue whale’s heart may weight 1000 pounds (454,000 grams) It’s the size of a VW beetle! An elephant heart may weigh 75 pounds Heart rate about 10 bpm A mouse’s heart weighs ~ 10 grams Heart rate about 250 bpm Slide 11.2a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Coverings Pericardium – a double serous membrane Visceral pericardium On the surface of the heart Parietal pericardium Lines pericardial cavity Slide 11.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Coverings

The Heart: Coverings Pericardial cavity: between layers Serous fluid fills the space Fluid required for lubrication Heart moves!! Slide 11.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structure of the Heart – Coverings Figure 18.3

The Heart Wall Three layers Epicardium Outside layer This layer is the visceral pericardium Connective tissue layer Thin, shiny, slick Slide 11.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structure of the Heart Wall Epicardium = visceral pericardium Figure 18.3

The Heart: Heart Wall Myocardium Endocardium Middle layer Mostly cardiac muscle Very thick Endocardium Inner layer Endothelium (Simple squamous E.T) Slick, shiny Slide 11.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structure of the Heart Wall Myocardium Endocardium Figure 18.3

The Heart: Chambers Right and left side are separate systems Four chambers Atria Thin walled upper chambers Receiving chambers Right atrium (-O2 blood) Left atrium (+O2 blood) Slide 11.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

External Heart Anatomy Figure 11.2a Slide 11.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Chambers Ventricles Thick walled, lower chambers Pumping chambers Right ventricle: to pulmonary circuit (-O2 blood) Left ventricle To systemic circuit (+O2 blood) Slide 11.6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

External Heart Anatomy Figure 11.2a Slide 11.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Valves Function: to direct blood flow Two pairs Atrioventricular valves – between atria and ventricles Bicuspid (Mitral) valve (left) Tricuspid valve (right) “Active”: function with cardiac muscle Slide 11.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart Valves Figure 18.5c

The Heart: Valves Semilunar valves between ventricle and artery “Passive”: depend on blood pressure Pulmonary semilunar valve RV to pulmonary trunk Aortic semilunar valve LV to aorta Slide 11.8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart Valves Figure 18.5c

The Heart: Valves Valves open as blood is pumped through AV valves held in place by chordae tendineae (“heart strings”) Close to prevent backflow Slide 11.9 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart Valves Figure 18.5c

Operation of Heart Valves Figure 11.4 Slide 11.10 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Associated Great Vessels Great Arteries Aorta Leaves left ventricle Supplies systemic circuit Pulmonary trunk (artery) Leaves right ventricle Supplies pulmonary circuit Slide 11.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Great Arteries

The Heart: Associated Great Vessels Great Veins Venae cavae (superior, inferior) Enter right atrium Drain systemic circuit Pulmonary veins (four) Enter left atrium Drain pulmonary circuit Slide 11.11 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Great Vessels Figure 18.5c

Coronary Circulation The heart muscle has its own blood supply Part of systemic circuit Coronary arteries (+O2 blood) Cardiac veins (-O2 blood) Blood returns to the right atrium via the coronary sinus (-O2 blood) Slide 11.12 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Coronary Circuit, Anterior View Figure 11.2a Slide 11.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Coronary Circuit, Posterior View

The Heart: Conduction System Intrinsic conduction system (nodal system) Heart muscle cells contract without nerve impulses Heart has an intrinsic rhythm (“built in”) Slide 11.13a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Conduction System Specialized cardiac muscle tissue Sinoatrial (SA) node Pacemaker Atrioventricular (AV) node Atrioventricular bundle (of His) Bundle branches (R and L) Purkinje fibers Slide 11.13b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: conduction system Figure 11.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart Contractions Contraction is initiated by the sinoatrial node: “pacemaker” Sends information to all muscle cells of both atria Atria contract simultaneously Slide 11.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: conduction system Figure 11.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart Contractions Impulse transmission AV Node serves as “booster station” Sends impulse through AV bundle, along bundle branches Finally to Purkinje fibers Ventricle muscles contract simultaneously Slide 11.14a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Heart: conduction system Figure 11.5 Slide 11.14b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Heart: Cardiac Cycle Atria contract simultaneously Atria relax, then ventricles contract Systole = contraction of ventricles Diastole = relaxation of ventricles Slide 11.16 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

The Cardiac Cycle Figure 11.6 Slide 11.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

ECG P wave: QRS complex: T wave: Atrial depolarization. Ventricular depolarization. Atrial repolarization. T wave: Ventricular repolarization.

Heart Sounds “Lubb-dupp” – sound of valves closing First sound “lubb” – the AV valves closing Second sound “dupp” – the semilunar valves closing

The Heart: Cardiac Output Cardiac output (CO) Amount of blood pumped by each side of the heart in one minute CO = (heart rate) x (stroke volume) Stroke volume Volume of blood pumped by each ventricle in one contraction Slide 11.18 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cardiac Output Regulation Figure 11.7 Slide 11.19 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings