Download Blood Flow and Conduction

Systemic and Pulmonary Circulations
 Systemic circulation
 Blood flows from the left side of the heart
through the body tissues and back to the right
side of the heart
 Pulmonary circulation
 Blood flows from the right side of the heart to
the lungs and back to the left side of the heart
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Systemic & Pulmonary Circulations –
– SHADE RED & BLUE!
Figure 11.3
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The Heart: Associated Great Vessels
 Arteries – carry blood Away from the heart
 Aorta
 Leaves left ventricle
 Carries oxygenated blood
 Pulmonary arteries
 Leave right ventricle
 Carries deoxygenated blood
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The Heart: Associated Great Vessels
 Veins – carry blood back TO the heart
 Superior and inferior venae cavae
 Enter right atrium
 Carries deoxygenated blood
 Pulmonary veins
 4
 Enter left atrium
 Carries oxygenated blood
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The Heart: Associated Great Vessels
Notes – page 9
Figure 11.2c
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Blood Flow Through the Heart
 Superior and inferior venae cavae dump blood
into the right atrium
 From right atrium, through the tricuspid valve,
blood travels to the right ventricle
 From the right ventricle, blood leaves the heart as
it passes through the pulmonary semilunar valve
into the pulmonary trunk
 Pulmonary trunk splits into right and left
pulmonary arteries that carry blood to the
capillaries of the lungs for gas exchange
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Blood Flow Through the Heart
 Oxygen is picked up and carbon dioxide is
dropped off by blood in the lungs
 Oxygen-rich blood returns to the heart through
the four pulmonary veins
 Blood enters the left atrium and travels through
the bicuspid valve into the left ventricle
 From the left ventricle, blood leaves the heart via
the aortic semilunar valve and aorta to the rest of
the body
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Systemic and Pulmonary Circulations
Figure 11.3
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Coronary Circulation
 Blood in the heart chambers does not nourish the
myocardium
 The heart has its own nourishing circulatory system
consisting of:
 Coronary arteries —branch from the aorta to
supply the heart muscle with oxygenated blood
 Cardiac veins —drain the myocardium of blood
 Coronary sinus —a large vein on the posterior of
the heart, receives blood from cardiac veins
 Blood empties into the right atrium via the coronary
sinus
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Pg. 8, book page 363
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Homeostatic Imbalance (add this to your notes)
 When the heart beats at a rapid rate, the
myocardium may receive inadequate blood
supply because relaxation periods when blood
flows to heart tissue are shortened.
 Angina pectoris = crushing chest pain that
occurs when myocardium is deprived of
oxygen
 Myocardial infarction = “heart attack” occurs
from prolonged oxygen-deprived heart cells
that die
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The Heart: Conduction System
 Intrinsic conduction system (nodal system)
 Built into the heart tissue
 Heart muscle cells contract without nerve
impulses in a regular, continuous way
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The Heart: Conduction System
 Special tissue sets the pace:
 Sinoatrial node = SA node (“pacemaker”),
is in the right atrium
 Atrioventricular node = AV node, is at the
junction of the atria and ventricles
 Atrioventricular bundle = AV bundle
(bundle of His), is in the interventricular
septum
 Bundle branches are in the interventricular
septum
 Purkinje fibers spread within the ventricle
wall muscles
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Heart Contractions – Document can be found
online (Planbook and Ms. H’s website)
Figure 11.6
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Heart Contractions
 Contraction is initiated by the sinoatrial node (SA
node)
 It starts each heartbeat & sets the pace for the
whole heart
 Sequential stimulation occurs at other
autorhythmic cells
 Force cardiac muscle depolarization in one
direction—from atria to ventricles
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Heart Contractions
 Once SA node starts the heartbeat
 Impulse spreads to the AV node
 Then the atria contract
 At the AV node, the impulse passes through the
AV bundle, bundle branches, and Purkinje fibers
 Blood is ejected from the ventricles to the aorta
and pulmonary trunk as the ventricles contract
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Heart Contractions
 Tachycardia —rapid heart rate over 100 beats per
minute
 Bradycardia —slow heart rate less than 60 beats
per minutes
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The Heart: Cardiac Cycle
 Atria contract simultaneously
 Atria relax, then ventricles contract
 Systole = contraction
 Diastole = relaxation
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Filling Heart Chambers: Cardiac Cycle
Left atrium
Right atrium
Left ventricle
Right ventricle
Ventricular
filling
Atrial
contraction
Mid-to-late diastole
(ventricular filling)
Isovolumetric
Ventricular
contraction phase ejection phase
Isovolumetric
relaxation
Ventricular systole
(atria in diastole)
Early diastole
Figure 11.7
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The Heart: Cardiac Cycle
 Cardiac cycle—events of one complete heart beat
 Mid-to-late diastole—blood flows from atria
into ventricles
 Ventricular systole—blood pressure builds
before ventricle contracts, pushing out blood
 Early diastole—atria finish refilling, ventricular
pressure is low
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings