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37 Cards in this Set

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How does the action potential of a cardiac muscle differe from that of a neuron?
Duration is much longer for a cardiac muscle. Cardiac muscle has a pronounced plateau.
Describe Phase 0 of a cardiac action potential.
caused by the rapid opening of voltage-gated sodium channels. same as skeletal muscle
Describe Phase 1 of a cardiac muscle action potential.
caused by the closing of voltage-gated sodium channels. same as skeletal muscle
Descrive Phase 2 of cardiac muscle action potential.
this is the phase that makes cardiac muscle different. this is the plateau of the action potential created by the slow opening of voltage-gated calcium channels
Describe Phase 3 of cardiac muscle action potential.
caused by the closing of the calcium channels
Describe Phase 4 of cardiac muscle action potential.
represents the resting potential
What is a pacemaker cell?
specialized cardiac muscle fibers that are capable of spontaneously and rythmically depolarizing and repolarizing
Describe the sequence of events that occurs when the sinoatrial node depolarizes
1. The cells in the sinoatrial node depolarize.
2. A wave of depolarization spreads over the atria, causing contraction.
3. The wave of depolarization reaches the A-V node.
4. The electrical impulse travels down the A-V bundle into the left and right bundle branches.
5. The Purkinje fibers carry the impulse into the endocardial layer of myocardium.
6. The impulse radiates outward through the myocardium.
How is an ECG recorded?
Can be recorded through any one of the twelve leads.
Describe Phase 4 of cardiac muscle action potential.
represents the resting potential
How many limb leads are there in an ECG and where are they put?
3. Two wrist leads, one ankle lead that serves as a ground lead.
How many chest leads are there in an ECG?
6
What is a pacemaker cell?
specialized cardiac muscle fibers that are capable of spontaneously and rythmically depolarizing and repolarizing
Describe the sequence of events that occurs when the sinoatrial node depolarizes
1. The cells in the sinoatrial node depolarize.
2. A wave of depolarization spreads over the atria, causing contraction.
3. The wave of depolarization reaches the A-V node.
4. The electrical impulse travels down the A-V bundle into the left and right bundle branches.
5. The Purkinje fibers carry the impulse into the endocardial layer of myocardium.
6. The impulse radiates outward through the myocardium.
What are the three leads that aren't limb or chest leads called?
Augmented Leads
How is an ECG recorded?
Can be recorded through any one of the twelve leads.
Define a cardiac arrhythmia (dysrhythmia).
An abnormal cardiac rate or rhythm.
What is sinus tachycardia?
An elevation in heart rate observed at rest.
How many limb leads are there in an ECG and where are they put?
3. Two wrist leads, one ankle lead that serves as a ground lead.
What is sinus bradycardia?
Slow heart rate at rest caused by a decreased rate of depolarization and repolarization.
How many chest leads are there in an ECG?
6
What are the three leads that aren't limb or chest leads called?
Augmented Leads
Define a cardiac arrhythmia (dysrhythmia).
An abnormal cardiac rate or rhythm.
What is sinus tachycardia?
An elevation in heart rate observed at rest.
What is sinus bradycardia?
Slow heart rate at rest caused by a decreased rate of depolarization and repolarization.
Describe atrial flutter.
When the atrial depolarization doesn't occur normal and the atria may contract at 250-300 bpm. This can lead to atrial fibrillation
What is the cardiac arrhythmia known as a PVC?
Premature ventricular contraction that creates a wide and strange QRS complex with no P-wave.
What causes a PVC?
an ectopic focus
What is an ectopic focus?
a small area in the myocardium that that depolarizes randomly on its own and may cause the entire ventricle to then depolarize
What is a ventricular tachycardia?
When the ventircles contract much too fast, up to 250-300 bpm.
What is ventricular fibrillation?
when parts of the myocardium contract randomly and chaotically, causing blood to not be pumped.
What does a defibrillator do?
Sends a direct-current shock that depolarizes the entire myocardium, hopefully resetting all the cells.
What is CPR and what is it supposed to do?
Cardio-pulmonary resuscitation that forces oxygenated blood into the aorta and coronary arteries.
Describe what infarctions can be seen from analyzing the S-T segment?
Can be elevated or depressed when it is supposed to be flat.
Describe what infarctions can be seen in the T wave.
The T wave may be inverted.
Describe what infarctions can be seen in the Q wave.
The Q wave may increase in size.
What does cocaine do to the heart?
inhibits the reuptake of noropinephrine in the heart