Exam 4 - Lecture 4 Flashcards
Just inside fibrous pericardium is
Serious Pericardium, Parietal layer.
Directly connected to fibrous pericardium
Very very very thin stretchy layer that sits between parietal pericardium and the heart and what does it do?
Visceral layer
It is very clear and can hardly see it, allows heart to slide around easily
The more straight up and down phase 0 is, the more
fast sodium channels
Action potentials between 2 adjacent heart cells is done via
Gap junctions, mostly sodium, extremely low resistance and very fast.
Initiated by cells upstream
Downside of using gap junctions in heart
Bi-directional, can cause rogue electrical activity
APs can go backwards if hit at wrong time and cause alot of problems
What protects us from rogue action potentials in gap junctions in the heart?
Absolute refractory periods of cells in nodal tissue
Cell will not fire an AP in refractory period
3-lead EKG setup terms
Frontal/Coronal plane
Coronal or frontal plane can use
augmented leads or 3-lead ekg
the A in aVR, aVL means
augmented
Eyeball/sensor that is looking at current going towards or away from it is the
positive electrode
If current is going away from positive eyeball it will be
negative deflection
If current is going towards positive eyeball will be
positive deflection
Best lead that will see positive deflection in healthy patient
lead II on left foot/hip
Lead II eyeball on left foot/hip is positive or negative?
positive electrode
Lead I will have a positive or negative on left side of body? right?
positive left shoulder, negative right hand
There will always be _____ on left foot, _____ right arm, and _____ on left arm
2 positive electrodes (lead II and III); 2 negatives (Negative lead II, lead I); Positive lead I/negative lead III
Lead III will have a positive or negative electrode on left foot? left arm?
Positive left foot
Negative left arm
Which leads are on left foot? Number and charge
2 positives; Lead II and III
Which leads are on right arm? Number and charge
2 negatives; Lead II and I
Which leads are on left arm? Number and charge
Positive lead I, Negative lead III
In einthovens triangle, where are the leads on each side? charges?
Top side: lead I (left negative, right positive)
Left side: Lead II (Top negative, bottom positive)
Right side: Lead III (top negative, bottom positive)
Keep in mind, the bottom part of triangle is positive for both left and right, therefore the top is negative both sides. Lead I on top has left to right negative to positive.
what is the degree axis of the bottom side of Lead III of einthovens triangle?
top?
120 degrees
-60 degrees or +300 degrees
Who is einthoven
someone from europe, maybe a Duetsche scientist
What is the degree axis that the bottom side of Lead II of einthovens triangle? top?
60 degrees; -120 degrees, or +240 degrees
What is the degree axis of lead I?
Left side: 180
Right side: 0
Equipment needed for ekg
Lead selector/amplifier to amplify the signals
Chart recorder
Mean electrical axis of heart
59 degrees
Lead II angle is
60 degrees