EKG I Flashcards
Myocytes
cardiac cells, electrically polarized at rest
Polarity
is maintaned by membrane pumps necessary to keep the inside of the cells electronegatave
which pump maintains membrane electrical polarity
sodium/potassium
Ratio of Na to K
3 Na outside for every 2 K inside
What is needed to keep cell polarized
ATP
pacemaker cells
electrical power source of the heart
electrical conducting
the hard wiring of the heart
myocardial cells
the contractile machinery of the heart
what determines rate of depolarization
innate electrical characteristcs of the cell and the external neurohormonal input
action potential
a record of one elecrical cycle of depolarization & repolarization from a single cell
sinus node
dominant pacemaker of the heart, located in the RA, rate 60-100 BP, altered by Autonomic NS
Automaticity
all hearts cells posses ability to behave as a pacemaker.
intrinsic pacing SA node
60-100
intrinsic pacing atrial foci
60-75
junctional foci AV
40-60
Ventricular foci (his bundle, etc.)
30-40
horizontal small square distance in time
.04 sec
horizontal large square distance in time
.2 sec
vertical small square voltage
.1mV
vertical large square voltage
.5mV
P Wave
atrial depolarization
3 parts of ventricular conduction
1-bundle of Hi, 2-Bundle Branches, 3-Terminal Purkinje fibers