Cardiac Electrophysiology. Flashcards
The AV Valve:
Regulates the movement of blood between the two chambers.
The atrium wall contains less ______ than the ventricular wall:
Cardiac muscle.
More cardiac tissue in the left ventricle than the :
Why?
Right ventricle.
This is because the left ventricle needs more pressure to drive blood from through the systemic circuits.
Cardiac muscle tissues are linked by:
Electrical synapses.
Cardiac electrical synapses are located:
Located in specialized structures called intercalated disks.
They allow for fast synchronized responses to stimuli.
Autorhythmic:
An action potential is generated within muscle tissue.
Cardiac muscle is autorhythmic.
Types of cardiac muscle cells:
Contractile cell.
Conducting cell.
Contractile cells:
Generate the force that pumps blood.
Not autorhythmic.
Conducting cells:
Do not generate force.
These cells generate action potentials and rapidly propagate them through muscle tissue.
Some conducting cells are located in two groups:
SA node & the AV node.
Both are located in the right atrium.
SA node lies:
Near the junction with the superior vena cava.
The AV node lies:
Near the right AV valve.
Most conducting cells are organized into:
Bundles or tracts.
What links the SA node to the AV node:
The Atrial internodal tract.
The AV node propagates action potential into the ventricles.
Into the ventricles.
The course of action of a cardiac action potential.
AV node.
Bundle of His (common bundle).
R & L bundle branches.
Purkinje fibers.
* Rapid propagation of action potential.
Propagation of an action potential from the SA node to all other parts of cardiac muscle takes:
220 msec at a resting heart rate.
Propagation between contractile cells occurs at:
1 m/sec.
Propagation between most conducting cells is ____ times faster than contracting cells.
2-4 times faster.
The slow conduction time of the AV node allows:
Atria to contact before the ventricle.
Ventricular bundles:
Large bundles in the intraventricular septum.
Cells in SA node:
Generate an action potential at regular intervals.
Pacemaker potential:
When a cell completes an action potential, it immediately begins a slow depolarization.
The potential between two action potentials in the SA node.
Resting potential:
Membrane potential in the absence of stimulation.