Chapter 11- Part 1The Cardiovascular System
The Cardiovascular SystemThe 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 HeartThe 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: CoveringsThe Heart: Coverings The heart is covered by a
double sac of serous membrane, the pericardium.The pericardium contains twolayers: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: CoveringsThe 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 WallThe Three Layers of the Heart Wall
1. Epicardium Outside layer This layer is the
visceral pericardium already described
Connective tissue layer2. 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: ChambersThe 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: ChambersThe 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: ChambersThe 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: ChambersThe Heart: Chambers
The heart functions as a double pump: Right Side:
Pulmonary circuit pump
Left Side: Supply all body tissues
The Heart: Associated Great VesselsThe 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 CirculationBlood 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 CirculationBlood Circulation1. 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 CirculationBlood Circulation
Figure 11.3
Thickness of the VentriclesThickness 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: ValvesThe 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: ValvesThe 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: ValvesThe 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: ValvesThe 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: ValvesThe 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 ValvesFaulty 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 ValvesFaulty Valves
Treatment: A faulty valve can be replaced with a synthetic valve or a valve taken from a pig heart.