Chapter 11- Part 1
The Cardiovascular System
The Cardiovascular System
 A closed system of the heart
and blood vessels
 The heart pumps blood
 Blood vessels allow blood to
circulate to all parts of the body
 The function of the
cardiovascular system is to
deliver oxygen and nutrients
and to remove carbon
dioxide and other waste
products
The Heart
 Location
 Within the bony
thorax and is
flanked on each
side by the lungs
 Shape and Size
 Pointed apex directed toward left hip and rests
on the diaphragm
 The broader base (posterior/superior aspect of
heart) points towards the right shoulder and lies
beneath the 2nd rib
 About the size of your fist
The Heart: Coverings
 The heart is covered by a
double sac of serous
membrane, the pericardium.
The pericardium contains two
layers:
1. Visceral Pericardium (Epicardium) – Layer
next to heart; Tightly hugs the exterior surface
of the heart; Actually forms part of the heart
wall
2. Parietal Pericardium - Outside layer; Fibrous
layer that helps protect the heart and anchors
it to surrounding structures (diaphragm and
sternum)
The Heart: Coverings
 Serous Fluid - Fills the
space between the layers
of the pericardium
 Slippery, lubricating fluid
 Allows the heart to beat easily in a relatively
frictionless environment as the pericardial
layers slide smoothly across each another
 Pericarditis – Inflammation of the
pericardium; Often results in the decrease in
the amount of serous fluid
 Painful adhesions result that interfere with
heart movements (layers stick to each other)
The Three Layers of the Heart Wall
1. Epicardium
 Outside layer
 This layer is the
visceral pericardium
already described
 Connective tissue layer
2. Myocardium
 Middle layer
 Mostly cardiac muscle; layer that actually contracts
3. Endocardium
 Inner layer
 Thin glistening sheet of endothelium that lines the
heart chambers
The Heart: Chambers
 Right and left side
act as separate
pumps
 Four chambers
 Atria - Receiving chambers
• Not important in the pumping activity of the heart
• Right atrium and left atrium
 Ventricles - Discharging chamber
 Actual pumps of the heart
 Thick walled
 Right ventricle and left ventricle
The Heart: Chambers
 The heart is somewhat
twisted:
 Anterior surface of the
heart is formed
mostly by the right
ventricle
 The apex of the heart
is formed by the left
ventricle
The Heart: Chambers
Septums that divide the heart longitudinally:
 Interventricular Septum – Divides
and separates the two ventricles
from each other
 Interatrial Septum - Divides
and separates the two atria
from each other
The Heart: Chambers
 The heart functions
as a double pump:
 Right Side:
Pulmonary
circuit pump
 Left Side:
Supply all body
tissues
The Heart: Associated Great Vessels
 Aorta - Leaves left
ventricle
 Pulmonary
Arteries - Leave
right ventricle
 Vena Cava - Enters
right atrium
 Pulmonary Veins
(four) - Enter left
atrium
Blood Circulation
1. The superior and inferior vena cava deliver oxygen
poor blood from the veins of the body to the right atria
2. Right ventricle
3. Pulmonary arteries to the lungs to get oxygen and
drop off carbon dioxide
4. Oxygen rich blood is returned to the left side of the
heart through the four pulmonary veins
5. Left atria
6. Left ventricle
7. Oxygen rich blood is pumped out of the heart into the
aorta, from which the systemic arteries branch to
supply essentially all body tissues
Blood Circulation
1. Pulmonary Circulation – Circulation from the
right side of the heart to the lungs and back to
the left side of the heart
•
It’s only function is to carry blood to the lungs for
gas exchange and then return it to the heart
2. Systemic Circulation – Circulation from the
left side of the heart to the body tissues and
back to the right side of the heart
•
It supplies oxygen- and nutrient-rich blood to all
body organs
Blood Circulation
Figure 11.3
Thickness of the Ventricles
 Left Ventricle

Is the systemic pump that pumps blood over a
much longer pathway


Its walls are
substantially thicker
than those of the
right ventricle
More powerful pump
than the left ventricle
 Right Ventricle

Not as powerful or as
thick as the left ventricle
The Heart: Valves
 Allow blood to flow in
only one direction
 Four valves total (two
AV valves and two
semilunar valves)
 Atrioventricular (AV) Valves – Located
between the atria and ventricles
 Left AV Valve – Called the bicuspid valve or the
mitral valve (contains two cusps or flaps)
 Right AV Valve – Called the tricuspid valve
(contains three cusps or flaps)
The Heart: Valves
 Semilunar Valves –
Located between the
ventricle and artery
 Pulmonary
Semilunar Valve –
Right side of heart
(contains three cusps)
 Aortic Semilunar
Valve – Left side of
heart (contains three
cusps)
The Heart: Valves
 Valves open (flaps hang
limply) as blood is
pumped through
 Close to prevent backflow
 As the ventricles contract,
the pressure causes the
flaps to be forced upward,
closing the valves
The Heart: Valves
 The flaps of the AV
valves are held in a
closed position by the
chordae tendineae
 Tiny white cords
 Anchor the cusps to
the walls of the
ventricles, so that they
don’t blow upward into
the atria (like an
umbrella being turned
inside out by a gusty
wind)
The Heart: Valves
 Each set of valves operates at a different time  The AV Valves:
 Open during heart relaxation
 Closed when the ventricles are contracting
 Semilunar Valves:
 Open (forced open) when the ventricles contract
 Closed during heart relaxation
 The “lub-dup” sound of the heart is from the
opening and closing of the valves.
Faulty Valves
 The heart can function
with “leaky” valves as
long as the damage is
not too great.
 However, severely
deformed valves can
seriously hamper cardiac function.
 If blood backflows too much, the heart repumps
the same blood.
 If the flap stiffens, the heart’s workload increases,
and ultimately the heart weakens and may fail.
Faulty Valves
 Treatment: A
faulty valve can
be replaced with
a synthetic valve
or a valve taken
from a pig heart.