Electrical Physiology Flashcards
What is the resting concentration of K+ in and out of cell?
150 mmol in
4 mmol out
What is the resting potential of a muscle cell?
-90mV
What pumps keeps Ca and Na ions out of the cell (ie. higher concentration)?
Na+/K+ ATPase
Na+/Ca++ exchanger
Ca++ ATPase
True False: systole is the state of depolarization
true
Describes the phases of myocardial electrical activity:
Phase 0: depolarization –> influx of Na
Phase 1: closure of Na pumps (peak)
Phase 2: plateau phase –> Ca into the cell and K out (membrane voltage stays constant)
Phase 3: K out and hyperpolarises
Phase 4: repolarization to resting membrane
What are pacemaker cells?
Cells that can spontaneous trigger another activation by slow deploarization via slow diastolic inward leak of Na+
Left anterior descending artery problems can be detected by which leads?
V2 to V5
Lateral leads (ie I, and aVL) can detect which coronary problem?
Circumplex artery
Inferior Leads (ie. II, III, aVF) can detect which coronary problems?
Posterior descending artery
What are the unipolar limb leads?
aVR, aVL, aVF
What are the bipolar limb leads?
I, II, III
What are the chest leads?
V1 to V6
Where does normal beat begins?
sino-atrial node, located at the junction of the right atrium and the superior vena cava
T or F: the wave of depolarization from SA node travels rapidly within the AV node?
False: there is an expected delay
What does a P wave represent?
deploarization of atria
What does th QRS complex represent?
depolarization of ventricle muscle cells (endocardium)
What does T wave represent?
repolarization of ventricle cells (epicardium)
When would you expect to see a second upward deflection in a QRS complex?
A second upward deflection (seen in bundle branch blocks) is referred to as R ′
Whats the PR(PQ) segment
delay between atrial and ventricular deploarization
What is the QT segment?
time from ventricular deploratization until full repolarization (ie. end of T wave)
What are the lateral leads?
I, aVL, V5, V6
What are the inferior leads?
II, III, aVF, V5, V6
What does a large Q wave signify?
myocardial damage/scar
When would you expect to see Q waves in inferior leads?
if initial septal depolarization a bit superior as well as left
What is the most common cause of of ST/T abnormalities?
ischemia
What happens to the electrical activity during ischemia?
less positive systole, and less negative diastole and resting membrane
What happens to the ECG for sub-endocardium ischemia?
Marked ST depression, and T wave abnormal (T waves maybe inverted / bi-phasic)
What happens to the ECG for trans-mural ischemia?
ST- elevation
What happens to ECG in K+ imbalances?
severe increase in K+ in blood
(eventually –> sine wave pattern) –> depressed P wave, long QRS complex, increased T wave
derease in K+ (Mg++) in blood
(long QT, T wave changes, U waves)
