Human Anatomy, 3rd editionPrentice Hall, © 2001

The Heart

Chapter 21

Human Anatomy, 3rd editionPrentice Hall, © 2001

Introduction– Cardiovascular system – distributes blood

• Pump (heart)

• Distribution areas (capillaries)

– Heart has 4 compartments• 2 receive blood (atria)

• 2 pump blood out (ventricles)

• Vessels

– Veins return blood to the heart– Arteries take blood away from the heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

An Overview of the Circulatory System

Human Anatomy, 3rd editionPrentice Hall, © 2001

Superficial Anatomy of the Heart– Atria = “entrance ways”

• Thin-walled

• Upper chambers

– Ventricles = “hollow spaces”• Thick, muscular

– Apex points down & tips slightly to the left– Base is superior

• Great vessels attach

Human Anatomy, 3rd editionPrentice Hall, © 2001

Orientation & Superficial Anatomy

Human Anatomy, 3rd editionPrentice Hall, © 2001

Anterior View of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Anterior View of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Posterior View of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Posterior View of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Coverings of the Heart– Pericardium = “around the heart”

• Visceral pericardium = epicardium

• Parietal pericardium

• Pericardial space contains pericardial fluid

Human Anatomy, 3rd editionPrentice Hall, © 2001

Pericardium

Human Anatomy, 3rd editionPrentice Hall, © 2001

Internal Anatomy of the Heart– Chambers of the heart

• Right & left atrium– Separated by the interatrial septum

• Right & left ventricle– Separated by the interventricular septum

Human Anatomy, 3rd editionPrentice Hall, © 2001

Structure of the Heart Wall– 3 layers

• Epicardium = “upon the heart”

• Myocardium is the middle layer– Thickest layer

– Cardiac muscle

– Has papillary muscles

– Chordae tendinae attach flaps of the AV valves to the papillary muscles

• Endocardium = “inside the heart”

Human Anatomy, 3rd editionPrentice Hall, © 2001

Organization of Muscle Tissue

Human Anatomy, 3rd editionPrentice Hall, © 2001

Structure of the Heart Wall

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Great Vessels– Superior & inferior vena cava

• Return blood from body to right atrium

– Coronary Sinus• Returns blood from heart wall to right atrium

– Pulmonary artery• Takes blood (deoxygenated) from right ventricle to

lungs

– Pulmonary veins• Returns blood (oxygenated) from lungs to left

atrium

– Aorta• Takes blood from left ventricle to body

Human Anatomy, 3rd editionPrentice Hall, © 2001

Valves of the Heart– Atrioventricular (AV) valves separate the atria

from the ventricles• Tricuspid valve – right

• Bicuspid valve (mitral) – left

– Semilunar valves separate the ventricles from the great vessels

• Pulmonary semilunar valve

• Aortic semilunar valve

– Heart sounds

Human Anatomy, 3rd editionPrentice Hall, © 2001

Valves of the Heart (Ventricular Diastole)

Human Anatomy, 3rd editionPrentice Hall, © 2001

Valves of the Heart (Ventricular Systole)

Human Anatomy, 3rd editionPrentice Hall, © 2001

Heart Sounds

Human Anatomy, 3rd editionPrentice Hall, © 2001

Coronary Circulation

Vessels that supply the myocardium itself

Right coronary artery

Left coronary artery

Cardiac veins

Human Anatomy, 3rd editionPrentice Hall, © 2001

Coronary Circulation

Human Anatomy, 3rd editionPrentice Hall, © 2001

Cast of Coronary Vessels

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Cardiac Cycle– The contraction pattern of the myocardium

• Determined by the conduction system

– Systole = contraction– Diastole = relaxation– Both atria contract at the same time– Both ventricles contract at the same time– Atria alternate with ventricles

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Cardiac Cycle

Human Anatomy, 3rd editionPrentice Hall, © 2001

Conduction System of the Heart– The average heart rate is 72 beats/min.

– Depolarization stimulates contraction

– Depolarization begins in the sinoatrial (SA) node• Pacemaker

– Depolarization spreads through atria• Atria contract

– Atrioventricular (AV node) depolarizes

– Depolarization travels down the AV bundle (bundle of His)

– Depolarization spreads up the ventricular walls via Purkinje fibers.

• Ventricles contract

Human Anatomy, 3rd editionPrentice Hall, © 2001

Conducting System of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Conducting System of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Conduction System of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Conducting System of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Conducting System of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Conducting System of the Heart

Human Anatomy, 3rd editionPrentice Hall, © 2001

Electrocardiogram– ECG = a recording of electrical events in the

heart• P wave = atrial depolarization

• QRS wave = ventricular depolarization

• T wave = ventricular repolarization

Human Anatomy, 3rd editionPrentice Hall, © 2001

Electrocardiogram

Human Anatomy, 3rd editionPrentice Hall, © 2001

Electrocardiogram

Human Anatomy, 3rd editionPrentice Hall, © 2001

Disorders– Abnormal heart rates

• Bradycardia

• Tachycardia

• Fibrillation

– Angina pectoris– Myocardial infarction