Human Anatomy, 3rd edition Prentice Hall, © 2001 The Cardiovascular System Chapter 13

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Cardiovascular System

Chapter 13


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


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


The Coverings of the Heart

• Pericardium = “around the heart”– Visceral

pericardium = epicardium

– Parietal pericardium

– Pericardial space contains pericardial fluid


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


Structure of the Heart Wall

• Epicardium = “upon the heart” = visceral pericardium– Dense fibrous

connective tissue

• Myocardium is the middle layer– Cardiac muscle

• Endocardium = “inside the heart”– Simple squamous

epithelium


The Great Vessels

• Superior & inferior vena cava– Return blood from

body to right atrium

• Coronary Sinus– Returns blood from

heart wall to right atrium


The Great Vessels• Pulmonary veins

– Return blood (oxygenated) from lungs to left atrium

• Aorta– Takes blood from

left ventricle to body

• Pulmonary artery– Takes blood

(deoxygenated) from right ventricle to lungs


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


Valves of the Heart (Ventricular Diastole)


Valves of the Heart (Ventricular Systole)


Coronary Circulation

• Vessels that supply the myocardium itself– Right coronary artery– Left coronary artery – Cardiac veins


Cast of Coronary Vessels


The Cardiac Cycle• Contraction pattern

of the myocardium– Determined by the

conduction system– Systole =

contraction– Diastole = relaxation

• Both atria contract• Both ventricles

contract• Atria alternate with

ventricles


Conduction System of the Heart• The average heart rate is 72 beats/min.• Depolarization stimulates contraction


Conducting System of the Heart

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

Conduction System of the Heart

•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


Electrocardiogram

– ECG = a recording of electrical events in the heart• P wave = atrial depolarization• QRS wave = ventricular depolarization• T wave = ventricular repolarization


Electrocardiogram


Electrocardiogram


Disorders

• Abnormal heart rates– Bradycardia– Tachycardia– Fibrillation

• Angina pectoris

• Myocardial infarction


Blood Vessels


Functions of Blood Vessels

• Carry blood away from the heart - arteries

• Transport blood to tissues - capillaries

• Return blood to the heart – veins


Walls of Blood Vessels

• 3 layers– Inner layer is endothelium = tunica intima

• Simple squamous epithelium

– Middle layer = tunica media• Smooth muscle

– Outer layer = tunica externa• Dense fibrous connective tissue


Atherosclerosis


Arteries

• Elastic arteries– Large

• Muscular arteries– Medium-sized

• Arterioles– Very small– Capable of

vasoconstriction and vasodilation


Systemic Arterial System


Major Arteries of the Trunk


Arteries of the Chest and Upper Extremity


Capillaries

• All blood-tissue exchange occurs here

• Tissue = tunica intima only


Capillary Bed with Precapillary Sphincters


Veins• Venules

– Very small – Contain only tunica intima

and tunica externa

• Medium-sized veins and large veins– Contain same 3 layers as

arteries– Tunica media thinner – Tuna externa - thickest

layer


Veins with Valves• Some veins contain valves – prevent blood

from flowing backwards


Varicose Veins

• www.sirweb.org/patPub/varicoseVeinMain.shtml

www.veinhelp.com/varicoseVeins.htm


Systemic Venous System


Venous System of the Trunk and Upper Limb


Blood Flow– Blood flows because of different pressures in the

system• Mean pressure in aorta = 100 mmHg

– Pressure decreases continuously through arterial and venous system• Arteries = 100 – 40 mmHg• Arterioles = 40 – 25 mmHg• Capillaries = 25 – 12 mmHg• Venules = 12 – 8 mmHg• Veins = 8 – 5 mmHg• Vena cava = 2 mmHg


Blood Pressure– Definition – force exerted by blood on the wall

of any blood vessel– Clinical use – refers to pressure in the arteries

• Ventricles contract (systole)– Arterial pressure rises – Systolic pressure

• Ventricles relax (diastole)– Arterial pressure drops– Diastolic pressure

• Average blood pressure– 120/80 (young male)– 110/70 (young female)

– Hypertension

Documents

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Cardiovascular System Chapter 13