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Electrical Activity of the
Heart
Chloe, Chanel, Raj
Conducting System
 AV node
 Sa node
 Purkinje fibers
 Bundle of his
SA node
Sinoatrial node
Specialized group of cardiac
muscle cells that don’t contract
located in the right atrium
of the heart
Adapted to automatically
generate impulses
generator of heart rhythm
Basically the pace maker
Function
 It triggers the electrical impulses that are carried
around to other heart cells
 The electrical impulses cause the atria to contract
at a rate of 60 to 100 beats per minute
 Signals atria to contract, passes the blood to
bottom
 Causes contraction
AV node
 Atrioventricular node
 electrically connects atrial and ventricular
chambers
 specialized tissue between the atria and the
ventricles of the heart
 Also automatically generates impulses- cause
contraction
Functions
 begins when it gets an electrical impulse from the SA node
 The rhythm of the heart contractions is set by the AV node. It
delays the impulse by about 0.12 seconds.
 This is delay is very important as it helps the atria eject the
blood in them into the ventricles before the contraction of the
ventricles.
 The delay also helps in protecting the ventricles from atrial
arrhythmia (type of arrhythmia).
 Sends the signal it receives to the fibers below, opens the
semilunar, blood is forced out
 http://www.youtube.com/watch?v=0xUifyll2Oc
 http://www.youtube.com/watch?v=lIQXzgesdDg
Purkinje fibers
 located in the inner ventricular walls of the heart,
just beneath the endocardium.
 consist of specialized cardiomyocytes that are able
to conduct cardiac action.
 allow the heart's conduction system to create
synchronized contractions of its ventricles, and are
therefore essential for maintaining a consistent
heart rhythm.
Bundle of his
 collection of heart muscle cells, known as cardiomyocytes,
specialized for electrical conduction that transmits electrical
impulses.
 The fascicular branches then lead to the Purkinje fibers
which provide electrical conduction to the ventricles, causing
the cardiac muscle of the ventricles to contract at a paced
interval.
 Basically directs orders to branches that allow a Heart to
contract. These branches that the His bundle directs, are the
Purkinje fibers.
EKG- What is it?
 Electrocardiogram
 Checks for problems with the electrical activity of your heart
 Natural electrical system causes the heart muscle to contract
and pump blood
 Translates electric activity in heart into line tracings on paper
 Spikes and dips in line tracings called waves
Why Is it done?
 Find cause of unexplained chest pain
 Find cause of symptoms of heart disease
 Check thickness of heart chambers
(hypertrophied)
 Check effectiveness of medicines
 Check overall health of heart
How it’s done
 EKG paste placed between the electrodes and
your skin to help conduction of electrical impulses
 Several electrodes are attached to the skin and
hooked to machine
 Machine traces heart activity on paper
Works Cited
 http://www.beltina.org/health-dictionary/atrioventricular-avnode.html
 http://biology.about.com/library/organs/heart/blatrionode.htm
 http://www.wisegeek.com/what-are-purkinje-fibers.htm
 http://medical-dictionary.thefreedictionary.com/Purkinje+fiber
 http://www.webmd.com/heart-disease/electrocardiogram
 http://www.nhlbi.nih.gov/health/health-topics/topics/ekg/
 http://www.beltina.org/pics/atrioventricular__av__node.gif