Module 8 ML-4 Flashcards
SA node
-where AP begins
-true pacemaker because it reaches threshold first
What is located at the bottom of the right atrium?
AV node
What is the purpose of the AV node
it is the only electrical connection between the atria and ventricles; it slows down the AP propagation
How does the AV node slow down the propagation
Cells are in a chain and there is less ion channel density
What makes AP propagate faster?
Bundle of His, bundle branches, and Purkinje fibers
What is the purpose of the bundle of his, bundle branches, and purkinje fibers
Make sure the mass is excited at the same time
What is located on the right side of the hear
Superior vena cava, SA node, AV node, right bundle branch, bundle of his, RV,, purkinje fibers, inferior vena cava
What is located on the left side of the heart?
Left atrium, left ventricle, left bundle branch
What is the conduction pathway steps
- SA node
-Atrial contractile cells
-AV node
-bundle of his
-bundle branches
-purkinje fibers
-ventricular contractile cells
Ventricular contractile cells
-these do the work
- all cells are connected by gap junctions
Implications of gap junctions/electrical syncytium
-one cell starts each AP (heartbeat)
-one diseased cell can cause fatal arrhythmia
-artifical pacemakers are possible to install
-no recruitment for strong heartbeats; every cell contracts with every heartbeat
P wave
represents atrial depolarization (SA node gets to threshold and triggers)
Why is there a flat line following the ECG tracing
AV node is too small to show anything on the ECG
What does the QRS complex represent
ventricular depolarization
Ventricular depolarization begins with
atrial relaxation and ends with excitation of both ventricles
