Rapid Interpretation of EKGs - Chapter 1 highlights Flashcards
A good review of basics.
Resting myocytes (aka polarized) have what electrical charge?
negative
When myocytes contract, what is their electrical charge?
positive
As the positive wave of depolarization within the myocytes flows toward a positive electrode, there is a _________ deflection recorded on EKG.
positive (or upward)
The generation of pacemaking stimuli by the SA node is known as what?
automaticity
What does the P wave represent?
atrial depolarization (contraction)
The AV valves have two functions, what are they?
- prevent backflow of blood to the atria
2. electrically insulate the ventricles from the atria
When the conducting pathway gets to the AV valves, where does it go from there?
the AV node
it sits between the AV valves
Which AV valve is between the right atrium and right ventricle?
tricuspid valve
(tRIcuspid is RIght side)
[got that one from the book, but i’m sure jake’s eye is twitching anyway]
Which AV valve is between the left atrium and the left ventricle?
mitral valve
mitraL is Left side
Cell to cell conduction of depolarization through the myocardium is carried by what kind of ions?
fast-moving sodium ions
Slow conduction through the AV node is carried by what ions?
slow-moving calcium ions
The AV node is connected to what?
the His bundle
What comes after the His bundle?
the right and left bundle branches
What are the His bundle and bundle branches “bundles” of?
purkinje fibers
Purkinje fibers use what type of ions for the conduction of depolarization?
fast-moving sodium ions
What do the purkinje fibers depolarize?
the ventricular myocytes
Do the purkinje fibers penetrate into the myocardium?
no.
(the terminal filaments of the Purkinje fibers spread out just beneath the endocardium, and thus depolarization begins at the inside lining and proceeds toward the outside surface (epicardium) of the ventricles)
What does the QRS complex represent?
depolarization of the ventricles
What is the name of the horizontal segment of baseline that follows a QRS complex?
the ST segment
From the beginning of the ST segment to the end of the T wave, what does this represent?
ventricular repolarization?
yes, ventricular repolarization
In regards to ventricular repolarization, what phase is the ST segment and what phase is the T wave?
ST segment - plateau phase
T wave - rapid phase
The QT interval (from the beginning of the QRS complex to the end of the T wave) represents what?
ventricular systole
The whole representation of the P wave, QRS complex, the T wave, and the baseline that follows until another P wave appears is known as what?
a cardiac cycle
Calcium ions cause what?
myocyte contraction
The outflow of potassium ions causes what?
repolarization of myocytes
Sodium ion movement produces what?
cell to cell conduction in the heart
except the AV node, which uses slow-moving calcium ions
