Cardiac Innervation Flashcards
Which cells perform the kinetic work of the heart?
Myocardial muscle cells (contractile cells)
Thin tracks through the muscle cells that initiate electricity
Conduction cells
How are cells joined together? What does this allow?
Gap junctions. Allows passage of electrical impulses to travel from cell to cell
What are contractile cells made up of?
Myofibrils
What are the 5 action potential phases?
0- depolarization
1- early repolarization
2- plateau - contraction
3- repolarization
4- resting state
In this phase, the cell is stimulated and prepares to contract
Depolarization
In this phase, the cell moves toward a slightly less positive state
Early repolarization
This is the contraction phase
Plateau stage
What is Ca++ responsible for?
Contraction of the cell
In this phase, the cell returns to resting state
Repolarization
In this phase, potassium comes back into the cell
Resting state
Intrinsic vs extrinsic innervation
Intrinsic- controls base HR
Extrinsic- gives heart signals to speed up or slow down
What is the order of intrinsic conduction pathway?
- SA node
- LA/RA (internodal tracts)
- AV node
- Bundle of His
- Right and left bundle branches
- Purkinje fibers
Which node is also known as the pacemaker?
SA node
Which node can generate pulses at a rate of 40-60 BPM and only needs to generate them if the SA node fails?
AV node
This bundle holds the atrial impulse until atrial contraction is complete and sends the impulse forward to the left and right bundle branches?
Bundle of His
What creates QRS complex on ECG?
Ventricular depolarization
What causes the T wave on ECG?
Repolarization
Which three ions are most responsible for depolarization?
Potassium, calcium and sodium
In the setting of a bundle branch block, what would happen to the QRS?
Get wider
