Transcript CARDIOVASCULAR SYSTEM

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Fully formed by the 4th week of embryonic
development
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Hollow Muscular Organ That Acts as a
Double Pump
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Continuous pump - once pulsations begin,
heart pumps endlessly until death
General
Size: approximately the size of a person’s fist
Coverings: Pericardium
Double layered sac
Contains 10 – 20 cc. Of pericardial fluid to reduce the
friction of the beating heart
Heart Wall
Myocardium: heart muscle; thicker on left side of the
heart
Endocardium: lining of heart chambers; endothelial
tissue continuous with the lining of the blood vessels
2 upper chambers of heart
Thin walls, smooth inner surface
 Responsible for receiving blood
 Right atrium receives deoxygenated (oxygen
poor) blood from the body through the superior
and inferior vena cava
 Left atrium receives oxygenated (oxygen rich)
blood from the lungs through the pulmonary veins
Ventricles
Atria
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2 lower chambers of the heart
Thicker walls, irregular inner surface
Responsible for pumping blood away from the
heart
 Right ventricle sends deoxygenated blood to the
lungs via the pulmonary arteries
 Left ventricle sends oxygenated blood to all parts
of the body via the aorta
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Septum: muscular wall dividing the heart into
right and left halves
Heart valves – prevents the backflow of blood
Papillary muscles
prevent heart valves from turning inside
out when ventricles contract
Chordae tendineae
prevent heart valves from turning inside
out when ventricles contract
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Superior and inferior vena cava: receive
deoxygenated blood from all parts of the body
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Pulmonary arteries: carry deoxygenated blood
to the lungs from the right ventricle
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Pulmonary veins: carry oxygenated blood to
the left atrium from the lungs
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Aorta: carries oxygenated blood to distribute to
all parts of the body
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Tough fibrous tissue
between the heart
chambers and major blood 
vessels of the heart
Gate-like structures to keep
the blood flowing in one
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direction and to prevent
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regurgitation or backflow of
blood
Tricuspid valve: between
the right atrium and the right
ventricle
Bicuspid/mitral valve:
between the left atrium and 
the left ventricle
Pulmonary semilunar
valve: between the right
ventricle and the
pulmonary arteries
Aortic semilunar valve:
between the left ventricle
and the aortic arch/aorta
Heart Sounds
When the AV
(atrioventricular) and
semilunar valves close,
they make the sound heard
as “lub-dub” (auscultated
with stethoscope)
d. Abnormal heart sounds
= murmur; valve pathology
Superior and inferior
vena cava
 Right atrium
 Tricuspid valve
 Right ventricle
 Pulmonary semilunar
valve
 Pulmonary arteries
 Lungs – (O2 and CO2
exchange - external
respiration)
 Pulmonary veins
 Left atrium
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Bicuspid/Mitral valve
Left ventricle
Aortic semilunar valve
Aorta - all parts of body
via arteries
Arterioles
Capillaries of individual
tissues (O2 and CO2
exchange = internal
respiration)
Venules
Veins
Superior and inferior
vena cava
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Right and left sides beat
together
Electrical impulses in the
heart cause the
myocardium to contract
in a cyclic manner
Cycle consists of a brief
period of rest called
diastole followed by a
period of ventricular
contraction
At the start of a cycle,
the atria contract
pushing blood into the
ventricles
 Then the atria relax
 Blood returning from the
body enters the right
atrium
 Blood returning from the
lungs enters the left
atrium
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While the atria are
filling, systole begins
and the ventricles
contract
Right ventricle pushes
blood into the
pulmonary artery so it
can go to the lungs for
oxygen
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Left ventricles pushes
blood into the aorta so
it can be carried to all
parts of the body
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Blood in the right side
of the heart is low in
oxygen and high in
carbon dioxide
When it gets to the
lungs, the carbon
dioxide is released into
the lungs and oxygen
is taken into the blood
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Oxygenated blood is
then carried to the left
side of the heart by the
pulmonary veins
Now the blood in the
left side of the heart is
high in oxygen and low
in carbon dioxide and
ready to be carried to
body cells
Electrical impulses originating in the heart cause the cyclic contractions of
the muscles
Starts at the SA node (sinoatrial), also called the pacemaker of the heart
-a group of nerve cells in the right atria sends electrical impulses
that spread over the muscles in both atria
-causes atria to contract
-after the electrical impulse passes through the atria, it reaches
the AV node (atrioventricular)
-The AV node picks up the impulse at a group of nerves cells located
between the atria and the ventricles
-It sends electrical impulses through nerve fibers into the septum
called the bundle of His
Bundle of His
divides into the right and left bundle branch
Right and left bundle branches
-pathways that carry the impulse down through the ventricles
-bundles subdivide into a network of fibers throughout the
ventricles called the Purkinje fibers
Purkinje fibers
-spread electrical impulse to all of the muscle tissue in the
ventricles
-causes the ventricles to contract
Electrical conduction pattern occurs approximately every 0.8 seconds
Movement of the electrical impulse can be recorded on an (ECG)
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Arteries
› Carries blood away from the heart
› Are more muscular and elastic than other blood
vessels
› Aorta is the largest artery
 Receives blood from the left ventricle
 Immediately begins branching into smaller arteries
Smallest branches of arteries are arterioles
 They join the capillaries
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Capillaries
› Connect arterioles and venuoles, the smallest of
veins
› Have thin walls
› Allows oxygen and nutrients to pass through to
the cells
› At the same time carbon dioxide and metabolic
(waste) products from the cells enter the
capillaries
Veins are blood vessels that carry blood
back to the heart
 Veins are thinner than arteries
 Most contain valves that prevent backwards
flow of blood
 Venules
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› Smallest of veins
› Connect to capillaries
› Venuoles join together and become larger to
form veins
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Superior and inferior vena cava
› Two largest veins
› Superior brings blood back from the upper part of
the body
› Inferior bring blood back from the lower part of
the body