Transcript Circulatory Systemx

The Circulatory System
Circulatory System
Also known as the
Cardiovascular System
Consists of:
 Heart
 Blood Vessels
 Blood
Functions of the
Circulatory System
1) Transports oxygen and
nutrients to all body cells
2) Transports carbon dioxide
and metabolic materials
away from the body cells
Blood Vessels
Include:
 Arteries
 Veins
 Capillaries
Arteries
Blood Vessels that carry blood
away from the heart
 More muscular and elastic
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than the other vessels
Largest artery is the Aorta
Smallest branches are
called arterioles
Join with capillaries
Contain oxygen rich blood
except the Pulmonary Artery
Veins
Blood vessels that carry blood back
to the heart
 Venules , the smallest branches of
veins, connect with the capillaries
(join together and become larger
veins)
 The 2 largest veins: Superior Vena
Cava and Inferior Vena Cava
 Veins are thinner and less muscle
tissue
 Most contain valves which keep the
blood flowing in one direction
Capillaries
Blood vessels that connect
arterioles (smallest arteries)
with venules (smallest veins)
 Smallest blood vessels
 Contain thin walls that allow oxygen and nutrients
to pass through to the cells
 Also, allow carbon dioxide and metabolic waste
products to enter these vessels for removal from
the cell
Heart
 Muscular, hollow organ
functions as pump
 Weighs less than one pound
 Size of closed fist
 Located in the mediastinal
cavity, between the lungs,
behind the sternum and
above the diaphragm
Heart Facts
 The heart contracts about 100,000 times each day
to pump the equivalent of 2,000 gallons of blood
through the body.
 The human heart beats 35 million times in a year.
 In a lifetime, the heart pumps around 1 million
barrels of blood.
Layers of the Heart
 Three layers of tissue include:
 Endocardium – smooth layer which lines the inside of
the heart
 Myocardium – thick, middle muscular layer
 Pericardium – double layered membrane or sac that
covers the outside of the heart
A lubricating fluid, pericardial fluid, fills the space
between the two layers. This fluid helps prevent friction
and damage to the membrane as the heart beats.
Septum
 A muscular wall that
separates the heart into a
right side and a left side
 Prevents blood from
moving between the 2
sides
 Upper part of the septum
is called the interatrial
septum
 Lower part of the septum
is called the
interventricular septum
Heart Chambers
 The heart is divided
into four parts, or
chambers.
 2 upper chambers
are called atrias
(atriums)
 2 lower chambers
are called ventricles
Blood Flow
(Right Side of Heart)
 The Right Atrium receives blood as it returns from
the body cells via the Superior Vena Cava and
Inferior Vena Cava.
 The Right Ventricle receives blood from the Right
Atrium and pumps the blood into the Pulmonary
Artery, which carries the blood to the lungs for
oxygen.
Blood Flow
(Left Side of the Heart)
 The Left Atrium receives oxygenated blood from
the lungs via the Pulmonary Veins.
 The Left Ventricle receives blood from the Left
Atrium.
 The blood is pumped into the Aorta for transport
to the body cells.
Heart
Valves
 One way valves in the
chambers of the heart
keep the blood flowing
in the right direction.
Heart Valves on Right Side
 The Tricuspid Valve is
located between the
right atrium and the
right ventricle (contains
3 cusps or leaflets).
 The Pulmonary Valve is
located between the
right ventricle and the
pulmonary artery (contain
3 cusps or leaflets).
Heart Valves on Left Side
 The Mitral (Bicuspid)
Valve is located between
the left atrium and the
left ventricle (contains 2
cusps or leaflets).
 The Aortic Valve is
located between the left
ventricle and the aorta
(2 cusps or leaflets).
Heart
Valves
This three dimensional image shows the heart valves
functioning. Look close at the 3D of the heart (on the right),
the leaflets of the tricuspid and aortic valves are partly
visible.
The 2 left images show the tricuspid and mitral valves
(above) and aortic and mitral valves (below).
http://www.heart-valve-surgery.com/heart-surgery-blog/2008/03/21/what-do-normal-heart-valves-look-like/
Cardiac (Heartbeat) Cycle
 Even though the 2 sides of the heart are separated
by the septum, these 2 sides work together in a
cyclic manner.
 The cycle consists of a brief period of rest called
diastole, followed by a period of ventricular
contraction, called systole.
Cardiac Cycle
Start of a cycle
Atria contracts
Blood pushed into ventricle
Atria relaxes
Blood enters from superior & inferior vena cava on
right side and blood enters from pulmonary veins on
left side
 Atria filling, systole begins, and the ventricle
contract
 Contraction of ventricles pushes blood into
pulmonary artery on right side and pushes blood
into aorta on the left side
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Beating Heart
 http://www.innerbody.com/anim/heart.html
Pulmonary Circulation
 Blood on the right side of the heart is deoxygenated
meaning it is very oxygen poor and high in carbon
dioxide.
 The blood enters the lungs via the pulmonary artery.
 When the blood arrives in the lung, the carbon
dioxide is released into the lungs, and then oxygen is
taken into the blood (occurs in capillary beds in
lungs) .
 Once the blood returns to the heart on the left side,
it is filled with oxygenated blood (oxygen rich).
Review
Right Side of Heart
Deoxygenated Blood
(Oxygen Poor)
Left Side of Heart
Oxygenated Blood
(Oxygen Rich)
Blood Flow Through
Right Side of Heart
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Superior Vena Cava and Inferior Vena Cava
Right Atrium
Tricuspid Valve
Right Ventricle
Pulmonary Valve
Pulmonary Artery
To the Lungs
DEOXYGENATED BLOOD
Blood Flow Through
Left Side of Heart
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From Lungs
Pulmonary Veins
Left Atrium
Mitral (Bicuspid) Valve
Left Ventricle
Aortic Valve
Aorta
To the Body
OXYGENATED BLOOD
Conductive Pathway
 Electrical impulses cause the cyclic contractions of
the heart. These impulses start
in the atria and then move
down through the ventricles.
1) Sinoatrial (SA) Node – group
of nerve cells in the right
atrium. “Pacemaker” of the
heart.
2) Atrioventricular (AV) Node –
group of nerve fibers between
the atria and ventricles.
Conductive
Pathway
3) Bundle of His – group of
nerve fibers in the septum.
4) Right Bundle Branch and
Left Bundle Branch – nerve
fibers that carry the impulse
down the ventricles.
5) Purkinje Fibers – a network
of nerve fibers located
throughout the ventricles.
Electrocardiogram
 This electrical conduction pattern occurs
approximately every 0.8 seconds.
 The electrical impulses can be recorded on an
electrocardiogram (ECG or EKG) and used to detect
abnormal activity or disease.
EKG:
Electrocardiogram
Arrhythmias
 If something interferes with the normal electrical
conduction pattern of the heart, then arrhythmias
occur.
 These abnormal heart rhythms can be life
threatening.
 Ventricular fibrillation (V-Fib) occurs when the
ventricles contract without coordination which
decreases blood output.
 A defibrillator (device which shocks the heart with
a electrical current) is used. After a successful
shock, the SA node is able to regain control.
Heart Review