The Cardiovascular System
Chapter 13
Human Anatomy, 3rd edition
Prentice 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 edition
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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 edition
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The Coverings of the Heart
• Pericardium =
“around the heart”
– Visceral
pericardium =
epicardium
– Parietal
pericardium
– Pericardial space
contains
pericardial fluid
Human Anatomy, 3rd edition
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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 edition
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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
Human Anatomy, 3rd edition
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The Great Vessels
• Superior & inferior
vena cava
– Return blood from
body to right atrium
• Coronary Sinus
– Returns blood from
heart wall to right
atrium
Human Anatomy, 3rd edition
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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
Human Anatomy, 3rd edition
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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
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Valves of the Heart (Ventricular Diastole)
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Valves of the Heart (Ventricular Systole)
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Coronary Circulation
• Vessels that supply the myocardium itself
– Right coronary artery
– Left coronary artery
– Cardiac veins
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Cast of Coronary Vessels
Human Anatomy, 3rd edition
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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
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Conduction System of the Heart
• The average heart rate is 72 beats/min.
• Depolarization stimulates contraction
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Conducting System of the Heart
• Depolarization begins in the sinoatrial (SA) node
– Pacemaker
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Conduction System of the Heart
•Depolarization spreads through atria, atria contract
Conducting System of the Heart
• Atrioventricular (AV node) depolarizes
• Depolarization travels down the AV bundle (bundle
of His)
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Conducting System of the Heart
• Depolarization spreads up the ventricular walls
via Purkinje fibers.
– Ventricles contract
Human Anatomy, 3rd edition
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Electrocardiogram
– ECG = a recording of electrical events in
the heart
• P wave = atrial depolarization
• QRS wave = ventricular depolarization
• T wave = ventricular repolarization
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Electrocardiogram
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Electrocardiogram
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Disorders
• Abnormal heart rates
– Bradycardia
– Tachycardia
– Fibrillation
• Angina pectoris
• Myocardial infarction
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Blood Vessels
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Functions of Blood Vessels
• Carry blood away from the heart - arteries
• Transport blood to tissues - capillaries
• Return blood to the heart – veins
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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
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Atherosclerosis
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Arteries
• Elastic arteries
– Large
• Muscular arteries
– Medium-sized
• Arterioles
– Very small
– Capable of
vasoconstriction
and vasodilation
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Systemic Arterial System
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Major Arteries of the Trunk
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Arteries of the Chest and Upper Extremity
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Capillaries
• All blood-tissue exchange occurs here
• Tissue = tunica intima only
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Capillary Bed with Precapillary Sphincters
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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
Human Anatomy, 3rd edition
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Veins with Valves
• Some veins contain valves – prevent blood
from flowing backwards
Human Anatomy, 3rd edition
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Varicose Veins
•
www.sirweb.org/patPub/varicoseVeinMain.shtml
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www.veinhelp.com/varicoseVeins.htm
Systemic Venous System
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Venous System of the Trunk and Upper Limb
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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
Human Anatomy, 3rd edition
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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
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