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The Cardiovascular System
“A muscular pump equipped with oneway valves and a system of large and
small plumbing tubes within which the
blood travels.”
= pump
= plumbing tubes
Early development of the heart and
circulatory system
• 2 weeks post-conception• 3 weeks• 4 weeks• By week 8-
During this period the fetal heart
is at great risk from agents that
may cause congenital defects.
RUBELLA
FETAL CIRCULATION
Before birth•
•
•
Umbilical Vessels1. one
2. two
To bypass the liver
Umbilical vein  ductus venosus  inferior vena cava  right atrium ->
u
To bypass the lungs
Right Atrium  Foramen Ovale  Left Atrium  Left Ventricle  Aorta  Body
(majority of blood)
Or
Right Atrium  Right Ventricle  Pulmonary Trunk  Ductus Arteriosis  Aorta 
Body
At birth or shortly thereafter
•
•
•
ligamentum arteriosum
Anatomy of the Heart
1. Location and Size
•
•
•
• Pointed APEX • BASE -
2. Coverings and wall of the heart
a. covered by double sac- PERICARDIUM
Parietal Pericardium
(pericardial fluid)
Visceral Pericardium
(outer layer heart)
Myocardium
Endocardium
b. Layers of Heart Wall
C. Chambers of the Heart
• Two receiving chambers• Two discharging chambers (pumps)• Right and left side separated by the – SEPTUM
a. upper septum =
b. lower septum =
AtriumRight VentricleLeft Ventricle-
Cardiac Muscles (myocardium)
A Schematic
• BLUE-pulmonary circuit
RED- systemic circuit
Great Vessels of the Heart
Pulmonary
Circuit
Systemic
Circuit
Valves of the Heart
• Located at entrance/exit ventricles
• Are 1-way, prevent back flow of blood
• Atrioventricular-
• Semilunar-
Lubb Vs. Dupp
Cardiac Circulation
• Only the _________________ is in direct
contact with the blood. Other heart tissue
must have its own blood supply
• CORONARY ARTERIES
• CARDIAC VEINS
Conduction System of the Heart
• Cardiac muscles can
• But
• Must have unifying control system to lend
efficiency to the heart1.
2.
a.
b.
c.
SA node (
)
to the
Atrial myocardium (
)
to the
AV node (
)
to the
AV bundle
to the
Bundle branches
to the
Purkinje fibers
followed by
Ventricular contraction (
)
Electrocardiography
“When impulses travel through the heart,
electrical currents are generated that
spread throughout the body. These
impulses can be detected on the body
surface and recorded with an
electrocardiograph.
Electrocardiogram- recording that traces
the flow of current through the heart.
• P Wave• QRS complex• T wave*atrial repolarization
Cardiac Output-
CO = Heart rate X Stroke Volume
stroke volume-
CO = 75 bpm X 70 ml/beat
CO = 5250 ml/min (average)
What factors affect cardiac output?