THE CARDIOVASCULAR SYSTEM

Chapter 14

Introduction

• Cardiovascular system: heart, blood and blood vessels

• Cardiac muscle – Makes up bulk of heart– Provides force to pump blood

• Function: transports blood

2

THE ANATOMY OF THE HEART

Introduction

• Located in the mediastinum

• Surrounded by pericardial sac– Fibrous pericardium: outer layer– Serous pericardium: inner layer

The Layers of the Heart Wall

• Epicardium: outermost layer

• Pericardial cavity: separates epicardium and serous pericardium

• Myocardium: middle muscular layer

• Endocardium: lines the heart

The Layers of the Heart Wall (cont’d.)

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

The Chambers of the Heart (cont’d.)

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

The Great Vessels of the Heart (cont’d.)

• 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

Four Chambers of the Heart and Great Vessels

The Valves of the Heart

• Atrioventricular– Tricuspid (three cusps)

• Between right atrium and right ventricle

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

– Cusps attach to ventricles by chordae tendineae

The Valves of the Heart (cont’d.)

• Semilunar– Pulmonary

• Right ventricle• Pulmonary trunk exits the heart

– Aortic• Left ventricle• Ascending aorta leaves the heart

BLOOD FLOW THROUGH THE HEART

Blood Flow Through the Heart (cont’d.)

• Two atria contract while ventricles relax

• Two ventricles contract while atria relax

• Deoxygenated blood returns from body to right atrium

• Sent to right ventricle, which pumps blood to lungs

Blood Flow Through the Heart (cont’d.)

• Oxygenated blood returns to left atrium

• Sent to left ventricle

• Left ventricle sends blood to the body via the ascending aorta

THE CONDUCTION SYSTEM OF THE HEART

The Conduction System of the Heart (cont’d.)

• Sinoatrial (SA) node: pacemaker; initiates impulse

• Atrioventricular (AV) node: sends impulse to AV bundle

• Bundle of His: sends impulses to both sides of system

The Conduction System of the Heart (cont’d.)

• Purkinje’s fibers: send impulse to myocardial cells

The Conduction System of the Heart (cont’d.)

20

Animation – The Heart

• See the conduction system at work in the 3-D Heart animation.

Click Here to Play Conduction System Animation

A CARDIAC CYCLE

A Cardiac Cycle (cont’d.)

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

• Systole: contraction phase

• Diastole: relaxation phase

SOME MAJOR BLOOD CIRCULATORY ROUTES

Some Major Blood Circulatory Routes (cont’d.)

• Systemic circulation – All blood leaving left ventricle (oxygenated)– All blood returning to right atrium

(deoxygenated)– Subdivisions

• Coronary circulation• Hepatic portal circulation

Some Major Blood Circulatory Routes (cont’d.)

• Pulmonary: blood flow to lungs for gas exchange

• Cerebral: route to the brain

• Fetal: between developing fetus and mother

ANATOMY OF BLOOD VESSELS

Anatomy of Blood Vessels (cont’d.)

• Arteries and veins have three layers– Tunica intima: innermost layers– Tunica media: middle layer– Tunica adventitia: outer layer

• Lumen: blood vessel cavity

• Anastomosis: junction of blood vessels

Anatomy of Blood Vessels (cont’d.)

• Arteries: thicker and stronger than veins

• Arterioles: small arteries attach to capillaries

• Capillaries: gas nutrient and waste exchange

Anatomy of Blood Vessels (cont’d.)

• Venules: connect capillaries to veins

• Veins: less elastic than arteries, contain valves

MAJOR ARTERIES AND VEINS OF THE BODY

Ascending Aorta Branches

• Right and left coronary arteries branch off and supply the heart

Aortic Arch Branches

• 1st branch: brachiocephalic artery– Right common carotid artery and right

subclavian artery

• 2nd branch: left common carotid artery– Left internal carotid artery and left external

carotid artery

Aortic Arch Branches

• 3rd branch: left subclavian artery– Vertebral artery, axillary artery, brachial artery

and radial and ulnar arteries

Thoracic Aorta Branches

• 10 pairs of intercostal arteries

• Bronchial arteries

• Esophageal arteries

• Phrenic arteries

Abdominal Aorta Branches

• Celiac trunk

• Superior and inferior mesenteric arteries

• Right and left renal arteries

• Right and left gonadal arteries

• Lumbar arteries

• Right and left common iliac artery– Femoral artery

Abdominal Aorta Branches (cont’d.)

• Veins– Found closer to surface than arteries– Converge with:

• Superior vena cava• Inferior vena cava

– Veins are often named identically to arteries

Veins Merging into the Superior Vena Cava

• Radial and ulnar veins form brachial vein– Empties into axillary vein

• Cephalic vein

• Basilic vein

• Subclavian vein

• Vertebral vein

Veins Merging into the Superior Vena Cava (cont’d.)

• Internal jugular vein

• Right and left brachiocephalic veins

• Azygos vein

Veins Merging into the Inferior Vena Cava

• Anterior and posterior tibial veins

• Peroneal vein

• Popliteal/femoral veins– External iliac vein

• Great saphenous veins

• Right and left common iliac veins

Veins Merging into the Inferior Vena Cava (cont’d.)

• Right and left gonadal veins

• Right and left renal veins

• Hepatic portal vein

• Right and left hepatic veins

Animation – Ventricular Fibrillation

• The following animation illustrates the seriousness of an ineffective quivering action of the ventricles of the heart, known as ventricular fibrillation

Click Here to Play Ventricular Fibrillation Animation

Animation – Congestive Heart Failure

• Read about this condition in the Health Alert box on Congestive Heart Failure (CHF) in your textbook.

• Now watch the congestive heart failure animation.

Click Here to Play Congestive Heart Failure Animation

Summary

• Named the layers of the heart wall

• Named the chambers and valves of the heart

• Described blood flow through the heart

• Described the conduction system of the heart

Summary (cont’d.)

• Discussed the stages of the cardiac cycle

• Compared the anatomy of a vein, artery and capillary

• Named the major blood circulatory routes and blood vessels