LeBlanc 1 Flashcards
Which structure in the heart is the slowest in its conduction? Why is this so important?
AV node
The delay allows the time for ventricular filling
Are purkinje fibers fast or slow in their conduction?
They are fast b/c of their gap jcns. They have low electrical resistance.
What is the purpose of atrial & ventricular myocytes?
They are designed for pumping.
What are the pacemaker cells?
SA node, AV node, purkinje fiber cells
After SA, what transmits the electrical impulse?
AV node, Bachmann’s bundle–interatrial/internodal tracts
Bundle of Hiss
Purkinje fibers
What are the contracting cells?
atrial & ventricular myocytes
What’s the deal w/ tetanus & cardiac muscle?
Cardiac muscle doesn’t achieve tetanus like skeletal muscle (would be dangerous) & it is b/c it has a long refractory period. Can’t get a summation of AP.
Where does the impulse go directly after it leaves the SA & before it goes to the AV?
Atrial muscle cells & the inter nodal tracts that are in the RA.
What does the Bachmann bundle do?
It transmits the impulse from the SA node in the RA to the LA. It is an intertribal tract.
What is the size of the AV node? How does this affect its resistance & delay?
AV node is small. This means high resistance. This causes the delay.
Aside from around the ventricles & at the apex of the heart…where do Purkinje fibers go?
Into papillary muscles.
What is the pathway of electrical activity in the heart?
SA node, inter nodal tracts, Bachmann’s tract to LA, AV node, Bundle of His, Left & Right Bundle Branch, Purkinje fibers.
What is an insulator of the AV node?
atrioventricular fibrous tissue.
What would retrograde excitation show on an ECG?
an inverted P wave
What is the Bundle of Kent?
Which disease is it present in?
What would this do to an ECG?
something that allows direct communication b/w atria & ventricles w/o usual AV delay.
Wolf Parkinson White Syndrome
distance b/w P & QRS would be shorter.
