Download The Electrical Impulses of the Heart*

• Your heart is a muscle that works
continuously like a pump
• Each beat of your heart is set in
motion by an electrical signal from
within your heart muscle
• The electrical activity can be
recorded by an electrocardiogram
(aka EKG or ECG)
• Each beat of your heart begins with an electrical
impulse from the sinoatrial node in the right
atrium
– A cluster of cells where electrical impulses are
generated
• When you heart’s right atrium is full with blood,
the electrical signal spreads across the cells of
your heart’s right atria.
• Signal causes atria to contract or squeeze, forcing
blood into the ventricles.
• The SA node sets the rate and rhythm of your
heartbeat.
– Known as the heart’s natural pacemaker.
• The signal arrives at the
atrioventricular (AV) node
between the atria and the
ventricles.
• Here the impulse slows for
an instant to allow your
heart’s right AND left
ventricles to fill with blood
– Pumps the breaks!
• The signal is released
and moves to the bundle
of His located in the
heart’s ventricles.
• The signal fibers divided
into left and right
branches which run
through the heart’s
septum
• The signal leaves the left
and right branches
through the Purkinje
fibers that connect
directly to the walls of
the heart’s ventricles
• The signal spreads
quickly across your
heart’s ventricles
• As the signal spreads,
both ventricles contract,
but not at exactly the
same moment…
– The left ventricles
contracts an instant
before the right.
• Right ventricle pushes
blood to the lungs
• Left ventricle pushes blood
to the rest of the body
• As the signal passes,
the walls of the
ventricles relax and
await the next signal.
• How fast the heart beats depends on the
body's need for oxygen-rich blood.
• At rest, the SA node causes your heart to beat
about 50 to 100 times each minute.
• During activity or excitement, your body
needs more oxygen-rich blood; the heart rate
rises to well over 100 beats per minute.
• The heart’s electrical system triggers the
heartbeat. Each beat of the heart is
represented on the electrocardiogram (EKG or
ECG) by a wave arm.
The normal heart rhythm
(normal sinus rhythm) shows the
electrical activity in the heart is
following the normal pathway.
The rhythm is regular and the
node is normal (about 50 to 100
beats per minute).
• Tachycardia: fast heart
rhythm (greater
than 100 beats per
minute)
• Bradycardia: slow heart
rhythm (less than 50
beats per minute)
• An arrhythmia
(also called
dysrhythmia) is
an irregular or
abnormal
heartbeat.
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•
•
•
•
Coronary artery disease
High blood pressure
Changes in the heart muscle (cardiomyopathy)
Valve disorders
Electrolyte imbalances in the blood, such as
sodium or potassium
• Injury from a heart attack
• The healing process after heart surgery
• Other medical conditions
• Palpitations: A feeling of skipped heartbeats,
fluttering, "flip-flops" or feeling that the heart
is "running away"
• Pounding in the chest
• Dizziness or feeling lightheaded
• Shortness of breath
• Chest discomfort
• Weakness or fatigue
• http://www.pbs.org/wnet/heart/educators/vi
deo-spark.html
• http://www.pbs.org/wnet/heart/educators/vi
deo2-spark.html
• As you watch take note of the questions that
accompany each clip and jot down your
observations.
• You will each select one
type of Heart Arrhythmia
Disorders
• You will conduct research
and create a presentation
on one of the disorders:
– Describe the disorder
– What are the signs and
symptoms
– What are the causes?
– What remedies are there
for treating the disorder?
• Atrial Fibrillation
• Atrial Flutter
• Supraventricular
Tachycardia
• Sick Sinus Syndrome
• Ventricular Fibrillation
• Ventricular Tachycardia
• Premature Contractions
• Heart Block