Chapter 14

The Cardiovascular System

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Introduction

• Cardiovascular system - heart, blood and blood vessels

• Cardiac muscle– makes up bulk of heart– provides force to pump blood

• Function - transports blood

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The Anatomy of the Heart

• Located in the mediastinum• Surrounded by pericardial sac

– fibrous pericardium - outer layer– serous pericardium - inner layer

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The Layers of the Heart Wall

• Epicardium - outermost layer• Pericardial cavity - separates epicardium

and serous pericardium• Myocardium - middle muscular layer• Endocardium - lines the heart

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©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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The Chambers of the Heart

• Upper chambers - right and left atria • Lower chambers - right and left ventricles• Chambers separated internally by septum• External separations

– coronary sulcus - separates atria and ventricles

– interventricular sulci - separate ventricles

©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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The Great Vessels of the Heart

• Superior vena cava– receives blood from upper body

• Inferior vena cava– receives blood from lower body

• Coronary sinus - drains blood from heart

©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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The Great Vessels of the Heart

• Pulmonary trunk - right and left artery– carries deoxygenated blood to lungs

• Pulmonary veins (four) - return oxygenated blood to heart

• Ascending Aorta - oxygenated blood out to body– aortic arch, descending thoracic, abdominal

The Valves of the Heart(Preventing Backflow)

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Atrioventricular Valves

• Tricuspid (three cusps)– between right atrium and right ventricle

• Bicuspid (two cusps)– between left atrium and right ventricle

• Cusps attach to ventricles by chordaetendineae

©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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Semilunar Valves

• Pulmonary– right ventricle– pulmonary trunk exits the heart

• Aortic– left ventricle– ascending aorta leaves the heart

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Blood Flow Through the Heart

The Conduction System of the Heart

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Distribution of Electrical Impulses Through the Heart

• Sinoatrial (SA) node - pacemaker, initiates impulse →

• Atrioventricular (AV) node - sends impulse to AV bundle→

• Bundle of His - sends impulses to both sides of system→

• Purkinje’s fibers - send impulse to myocardial cells

©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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A Cardiac Cycle

• One cycle– atria contract / ventricles relax– ventricles contract / atria relax

• Systole - contraction phase• Diastole - relaxation phase

Some Major Blood Circulatory Routes

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Systemic Circulation

• All blood leaving left ventricle (oxygenated)

• All blood returning to right atrium (deoxygenated)

• Subdivisions– coronary circulation– hepatic portal circulation

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Other Circulatory Routes

• Pulmonary - blood flow to lungs for gas exchange

• Cerebral - route to the brain• Fetal - between developing fetus and

mother

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The Anatomy of Blood Vessels

• Arteries and veins have three layers– tunica intima - innermost layers– tunica media - middle layer– tunica adventitia - outer layer

• Lumen - blood vessel cavity

©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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The Anatomy of Blood Vessels

• Arteries - thicker and stronger than veins• Arterioles - small arteries attach to

capillaries• Capillaries - gas nutrient and waste

exchange• Venules - connect capillaries to veins• Veins - less elastic than arteries, contain

valves

Major Arteries and Veins

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Aorta and Its Branches

• Ascending Aorta - right and left coronary arteries

• Aortic Arch– brachiocephalic, left common carotid artery,

left subclavian artery• Thoracic Aorta• Abdominal Aorta

©2006 by Thomson Delmar Learning, a part of the Thomson Corporation. ALL RIGHTS RESERVED.

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Veins

• Found closer to surface than arteries• Converge with

– superior vena cava– inferior vena cava

• Veins are often named identically to arteries