Exam 4 Flashcards
What connects the left Atrium to the SA node & its function?
The Interatrial pathway (Bachman’s Bundle) & to facilitate coordinated electrical action potentials.
What sends the signal from the SA node to AV node?
The 3 internodal pathways (anterior, middle & posterior).
What does Isotonic contraction refer to?
Looking at contractions using the same weight but with different stimuli intensity or rate.
What is basal tension?
A muscle at rest without contraction.
What is an isometric contraction?
A contraction, in which the overall muscle length does not change.
What are iK+ ATP channels & where are they found?
Channels that open in response to low ATP or ischemia to reduce metabolic rate. They are found in nodal and ventricular tissue.
What effect do beta adrenergists have on HCN channels?
They facilitate wider opening of the channels, which results in a faster signal propagation from rest to threshold= faster HR.
How long does it take the signal to travel to the Bundle branches once the AV node receives the signal?
0.13seconds. (AV node receives the signal at 0.03 seconds and the L & R Bundle branches receive the signal at 0.16 seconds).
Through what tissue does the Bundle of His penetrate?
The Atrioventricular fibrous tissue
What is the last part to receive the action potential signal & how long does it take starting from the bundle branches?
It is the superior left lateral part of the left ventricle & it takes 0.06 seconds.
What causes the signal delay from the atria to ventricles (2 reasons)?
There are fewer gap junctions in the AV node & the penetrating part of the Bundle of His are smaller in diameter.
What is the difference of Purkinjie cells compared to Atria cells?
Purkinjie cells are wider & have lots of gap junctions
How long does the signal travel from SA to AV node?
0.03 seconds
How long does it take the for the last part of the Atria to see the electrical signal?
It takes 0.09 seconds
How long does it take the electrical signal to spread throughout the right Atrium?
0.07sec
What would cause a divided or biphasic P-wave?
Most likely a dilated left Atrium. Could be fibrosis or scar tissue of Bachman’s Bundle.
What would cause a larger P-wave?
Right Atrium hypertrophy
How long is the AV node delay?
0.09 sec
What is the combined total delay in the Bundle of His?
0.04sec
When does the conduction signal reach the Bundle branches?
0.16
What relates to the PR interval?
Signal travel from SA node to the Bundle branches
Where is the QRS initiated?
At the Bundle branches. The left bundle branch fires first, which reflects as the Q-wave.
What is indicative of a QS wave & where would one see it?
Indicative of ischemia & seen in Lead II
How long does it take for the entire depolarization to occur?
0.22sec