Powerpoint 4 Flashcards
Each muscle strand of the myocardium consists of ____, ____, and ____.
Myofibrils, myosin, and actin
What are the components of the conduction system?
- SA node (sinus node)
- Inter-nodal pathways
- AV node (atrioventricular node)
- Bundle of HIS
- Bundle branches
- Purkinge fibers
What is located in terminal groove just below SVC on epicardial surface of RA?
SA node
The SA node initiates each cardiac cycle and is considered the ____ of the heart.
Pacemaker
What is the SA node rate?
60-100 bpm
Where is the AV node located?
It lies near the interatrial septum on floor of RA. It’s bordered by the TV septal leaflet and coronary sinus.
What is the AV node rate?
40-60 bpm
The AV node will delay impulses from SA node ____ second.
0.1 sec
The ____ ____ ____ is a thin bundle which connects the AV node to the right and left bundle branches.
Bundle of HIS
What is the bundle of HIS rate?
40-60 bpm
What sends impulse from SA node to LA for atrial contraction?
Bachman’s bundle
What are the two major branches that run through the ventricular septum from bundle of HIS to purkinge fibers?
Bundle branches
____ ____ course through endocardium of both ventricles, including trabeculations, papillary muscles, and moderator band.
Purkinge fibers
What is the rate of purkinge fibers?
20-40 bpm
What is it called when a resting cardiac cell is in a polarized state?
Resting membrane potential
____ ____ is created when an electrical impulse reaches a cardiac cell, and a threshold potential has been achieved.
Action potential
____ is when a change occurs inside a cell that causes the distribution of electric charges (electrolytes) to alter, leaving the cell with a less negative charge than the outside.
Depolarization
____ is the recovery from the depolarization state.
Repolarization
In what action potential phase is cardiac cell rapid depolarization? (this is where sodium rapidly enters the cell and potassium leaves the cell)
Phase 0-1
In what action potential phase is early rapid repolarization? (this is where potassium begins to reenter the cell as sodium leaves it)
Phase 1
Which action potential phase is known as the plateau phase? (marks the point at which CA+ enters the cardiac cell, causing cell contraction)
Phase 2
Action potential phase 2 coincides with the ____ segment of EKG.
ST
Which action potential phase is final rapid repolarization? (this is when the cell repolarizes by pumping sodium and CA+ out while potassium returns to the cell)
Phase 3
What action potential phase is considered the resting phase? (this is when sodium and calcium remain outside the cell while potassium remains inside the cell)
Phase 4
