Download Notes: Cardiovascular 2

Heart Continued
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Review Blood Flow
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Coronary Circulation
 Blood in the heart chambers does not nourish the
myocardium (heart muscle)
 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 where all of the cardiac
veins come together on the posterior of the heart,
receives blood from cardiac veins
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Coronary Circulation
 Blood empties into the right
atrium via the coronary sinus
Blood from the heart enters the
coronary arteries through a
branch at the base of the aorta.
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Coronary Circulation
 Angina pectoris:
-Chest pain due to inadequate supply of
oxygen to the muscle
-Indication some degree of coronary vessels
blockage
 Myocardial infarction:
- Medical term for heart attack
-Heart cells die from lack of blood supply
-Usually caused by blockage of one of the
coronary arteries
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The Heart: Conduction System
 Intrinsic conduction system (nodal system)
 Heart muscle cells contract, without nerve impulses,
they use nodes
 http://www.dailymotion.com/video/xhp35u_argosymedical-animation-sectioned-heart_tech
Heart beat sounds: “lub dub”
Sounds are made by the closing of the valves
Lub is the AV valves closing
Dub is the SA valves closing
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The Heart: Conduction System
 Special tissue:
 Sinoatrial node = SA node
(“pacemaker”), in right atrium
 Atrioventricular node = AV node, at
junction of the right atrium near the
interatrial septum
 Atrioventricular bundle = AV bundle
in the interventricular septum
 Bundle branches in the
interventricular septum
 Purkinje fibers spread within the
ventricle wall muscles
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SA node (sino-atrial node)
 acts as the heart’s
“pacemaker”
 cells whose primary
function is electrical
conduction, not
contractility
 the action potential
produced by its
depolarization spreads
across the atria
(remember that action
potential is the movement
of molecules across the
membranes of cells to
create electrical current)
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Heart Contractions
 Impulse spreads to
the AV node
 Then the atria
contract
 impulse passes
through the AV
bundle, bundle
branches, and
Purkinje fibers
 the ventricles
contract
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Heart Contraction
 http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter22/anim
ation__conducting_system_of_the_heart.html
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Heart Contractions
Figure 11.6
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The Heart: Cardiac Cycle
The cardiac cycle refers to 1 complete heart beat
Normally .8 sec for 1 cardiac cycle
Cardiac cycle includes:
 Systole = contraction
 Diastole = relaxation
Relates to the ventricles, unless otherwise stated
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Heart Contractions
Normal Heart Rate: 75 beats/min
 Tachycardia—rapid heart rate over 100 beats per
minute (tachy= fast)
 Bradycardia—slow heart rate less than 60 beats
per minutes (brady= slow)
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Filling Heart Chambers: Cardiac Cycle
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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
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