by adunn


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cardiovascular disease  (CVD)
disease affecting the heart peripheral blood vessels or both
coroary heart disease  (CHD)
a type of CVD; the single largest killer of americans
anastomosis
communication between two or more vessels
Poiseyille's law
a law of physiology stating that blood flow through a vessel is directly proportional to the radius of the vessel to the fourth power
cardiac cycle
the period of time from the end of one cardiac contraction to the end of the next
diastole
the period of time when the myocardium is relaxed and cardiac filling and coronary perfusion occur
systole
the period of the cardiac cycle when the myocardium is contracting
ejection fraction
ratio of blood pumped from the ventricle to the amount remaining at the end of diastole
stroke volume
the amount of blood ejected by the heart in one cardiaccontraction
preload
the pressure within the ventricles at the end of diastole; commonly called the end-diastolic volume
Starling's law of the heart
law of physiology stating that the more the myocardium is stretched, up to a certain amount, the more forceful the subsequent contraction will be
cardiac output
the amount of blood pumped by the heart in 1 minute
afterload
the resistance against which the heart must pump
chronotropy
pertaining to the heart
inotropy
pertaining to cardiac contractile force
dromotropy
pertaining to the speed of impulse transmission
intercalated discs
specialized bands of tissue inserted between myocardial cells that increase the rate in which the action potential is spread from cell to cell
syncytium
group of cardiac muscle cells that physiologicaly function as a unit
cardiac depolarization
a reversal of charges at a cell membrane so that the inside of the cell becomes positive in relation to the outside; the opposite of the cell's resting state in which the inside of the cell is negative in relation to the outside
resting potential
the normal electrical state of cardiac cells
action potential
the stimulation of myocardial cells, as evidenced by a change in the membrane electrical charge, that subsequently spread across the myocardium
repolarization
return of a muscle cell to its preexcitation resting state
excitablility
ability of the cells to respond to an electrical stimulus
conductivity
ability of the cells to propagate the electrical implulse from one cell to another
automaticity
pacemaker cells' capability of self-depolarization
contractility
ability of muscle cells to contract, or shorten
rhythm strip
electrocardiogram printout
electrocardiogram (ECG)
the graphic recording of the heart's electrical activity.  It may be displayed either on paper or on an oscilloscope
artifact
deflection on the ECG produced by factors other than the heart's electrical activity
bipolar limb leads
electrocardiogram leads applied to the arms and legs that contain two electrodes of opposite (positive and negative) polarity; leads I, II, and III.
Einthoven's triangle
the triangle around the heart formed by the bipolar limb leads
augmented limb leads
another term for unipolar limb leads (see the following definition), reflecting the fact that the ground lead is disconnected, which increases the ampliude of deflection on the ECG tracing
unipolar limb leads
elerocardiogram leads applied to the arms and legs, consisting of one polarized (positive) electrode and a nonpolarized referenced point that is created by the ECG machine combining two additional electrodes; also called augmented limg leads; lead aVR, aVL, and aVF
precordial (chest) leads
electrocardiogram leads applied to the chest in a pattern that permits a view of the horizontal plane of the hert; leads V1, V2, V3, V4, V5, and V6
QT interval
period from the beginning of the QRS to the end of the T wave
corrected QT (QTc)
The QT interval divided by the square root of the R-R interval
prolonged QT interval
QT interval greater than 0.44 sec.
refractory period
the period of time when myocardial cells have not yet completely reploarized an cannot be stimulated again
absolute refractory period
the period of the cardiac cyle when stimulation will not produce any depoloarization whatever
relative refractory period
the period of the cardiac cycle when a suffiiently strong stimulus may produce depolarization
tachycardia
a heart rate greater than 100 beats per minute
bradycardia
a heart rate less than 60 beats per minute
normal sinus rhythm
the normal heart rhythm
dysrhythmia
any deviation from the normal electrical rhythm of the heart
arrhythmia
the absence of cardiac electrical activity; often used interchangeable with dysrhythmia
ectopic focus
nonpacemaker heart cell that automatically depolarizes (plural: ectopic foci)
ectopic beat
cardiac depolarization resulting from depolarization of ectopic focus
noncompensatory pause
pause following an ectopic beat where the SA node is depoloarized and the underlyin cadence of the heart is interrupted
bruit
the sound of turbulent blood flow through a vessel; usually associated with atherosclerotic disease
compensatory pause
the pause following anectopic beat where the SA node is unaffected and the cadence of the heart is uninterrupted
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