Download Control of Heart Contractions

Control of Heart Contractions
What property is unique to cardiac muscle??
It can create it’s own stimulus
Conduction System of the heart because it
“conducts” an impulse causing the heart to
beat
Control of Heart Contractions
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SA (sinoatrial) NODE = PACEMAKER
It is the conductor of the heart
Located in right atrium
SA node sends out electrical impulse
Impulse spreads over atria, making them
contract
Travels to AV Node
Control of Heart Contractions
AV (atrioventricular) NODE
 Conducting cell group between atria and
ventricle
 “relay station”
 Carries impulse to bundle of His
Control of Heart Contractions
BUNDLE OF HIS
 Conducting fibers in septum
 At bottom of septum, bundle divides into R and L
branches
 These branches run back up the sides of the
ventricles
 These branches are called the Purkinje fibers
 Impulse shoots along Purkinje fibers causing
ventricles to contract
Control of Heart Contractions
ELECTROCARDIOGRAM (EKG or ECG)
 Device used to record the electrical activity of the
heart.
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Baseline of EKG is flat line
Control of Heart Contractions
ARRHYTHMIA – any change from normal
heart rate or rhythm
Normal pulse range 60-100
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Average pulse= 72
BRADYCARDIA – slow heart rate
(< 60 bpm)
TACHYCARDIA – rapid heart rate
(>100 bpm)
Control of Heart Contractions
Conduction defect any interruption of the signal
from the SA node to the AV node
 Ectopic pacemaker an abnormal signal generated
in heart tissue other than the SA node
 What might these people need?
 Artificial pacemaker
Ectopic pacemakers can cause:
 Premature atria contractions and
 Premature ventricular contractions
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Control of Heart Contractions
The worst arrhythmia is called:
VENTRICULAR FIBRILLATION
 The heart “quivers” like jello
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What treatment must be provided???
You must “defibrillate” them
or use the paddles and shock them