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The
Cardiovascul
ar System
Chapter 11
Introduction

Cardiovascular system – distributes blood
Pump (heart)
Distribution areas (capillaries)

Heart has 4 compartments
2 receive blood (atria)
2 pump blood out (ventricles)
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Vessels
Veins return blood to the heart
Arteries take blood away from the heart
An Overview of the
Circulatory System
The Heart
Superficial Anatomy of the
Heart

Atria
Thin-walled
Upper chambers
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Ventricles
Thick, muscular
Lower chambers
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Apex points down & tips slightly to the left
Orientation & Superficial
Anatomy
Anterior View of the Heart
Posterior View of the
Heart
The Coverings of the
Heart
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Pericardium
Visceral pericardium = epicardium
Parietal pericardium
Pericardial space contains pericardial fluid
Pericardium
Internal Anatomy of the
Heart
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Chambers of the heart
Right & left atrium
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Separated by the interatrial septum
Right & left ventricle
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Separated by the interventricular septum
Structure of the Heart
Wall
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3 layers
Epicardium
Myocardium is the middle layer
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Thickest layer
Cardiac muscle
Endocardium
Organization of Muscle
Tissue
Structure of the Heart
Wall
The Great Vessels
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Superior & inferior vena cava
Return blood from body to right atrium
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Coronary Sinus
Returns blood from heart wall to right atrium
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Pulmonary trunk (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
Valves of the Heart
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Atrioventricular (AV) valves separate the atria
from the ventricles
Tricuspid valve – right
Bicuspid valve (mitral) – left
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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
Coronary Circulation
Cast of Coronary Vessels
The Cardiac Cycle
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The contraction pattern of the myocardium
Determined by the conduction system
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Systole = contraction
Diastole = relaxation
Both atria contract at the same time
Both ventricles contract at the same time
Atria alternate with ventricles
The Cardiac Cycle
Conduction System of the
Heart
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
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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
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Atrioventricular (AV node) depolarizes
Depolarization travels down the AV bundle
Depolarization spreads up the ventricular walls via
Purkinje fibers.
Ventricles contract
Conducting System of the
Heart
Conducting System of the
Heart
Conduction System of the
Heart
Conducting System of the
Heart
Conducting System of the
Heart
Conducting System of the
Heart
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
Introduction

Blood vessels
Carry blood away from the heart - arteries
Transport blood to tissues - capillaries
Return blood to the heart – veins
Walls of Blood Vessels
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3 layers
Inner layer is endothelium
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Simple squamous epithelium
Middle layer
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Smooth muscle and elastic fibers
Outer layer
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Elastic and collagen fibers
Walls of Blood Vessels
Arteries
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Elastic arteries are the large arteries
Muscular arteries are the smaller arteries
Arterioles are very small, <0.5mm in
diameter
Capable of vasoconstriction and vasodilation
Systemic Arterial System
Major Arteries of the Trunk
Arteries of the Chest and
Upper Extremity
Capillaries
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The most important of the vessels
All blood-tissue exchange occurs here

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Tissue is entirely simple squamous epithelium
Occur in capillary beds with precapillary
sphincters
Capillaries
Capillary Bed
Veins
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Venules are very small
Contain no smooth muscle

Veins contain the same 3 layers as arteries
Middle layer is much thinner than in arteries
Outer layer is the thickest layer
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Some veins contain valves
Prevent blood from flowing backwards
Systemic Venous System
Venous System of the
Trunk and Upper Limb
Veins with Valves
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
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Definition – force exerted by blood on the wall
of any blood vessel
Clinical use – refers to pressure in the arteries
Ventricles contract (systole)
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Arterial pressure rises
Systolic pressure
Ventricles relax (diastole)
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Arterial pressure drops
Diastolic pressure
Average blood pressure
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120/80 (young male)
110/70 (young female)
Disorders
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Varicose veins
Hypertension
Atherosclerosis
Atherosclerosis