Fast: found in atrial muscle, ventricular & conductive cardiac tissue
phase 0 - Na+ channel open (fast)
phase 1 - ito (K channel) open
(fast Na channel closed)
phase 2 - Ca+2 channel opened (L-type, slow)
voltage-gated K channel open (iKR, iKS)
phase 3 - Ca+2 channel closes
voltage gated K channel open
phase 4 - resting configuration
Slow: SA AV Nodes
Nernst: RP sens to EC K, insens to EC Na

Pacemaker potential (resting PD)
- slow depolarization towards threshold

CG waves – recording electrical activity of the heart during its cycle
P wave – atrial depolarization
QRS complex – ventricular depolarization
T wave – ventricular repolarization (recovery)
PR interval (from the p wave to the q wave)– time between excitation of atria and ventricles
QRS duration – period of ventricular depolarization – slows down with conduction defects in bundle branches, Bundle of His, Perkinje fibers anything that slows down how rapidly the ventricle depolarizes and spreads out duration and decreases efficiency of the heart
QT interval (from beginning of Q to end of T wave)– duration of ventricular electrical activity- how long the ventricle is electrically active depending on the excitation of the ventricle to the end of the repolarization of ventricle
RR interval – period of cardiac cycle – (~ 0.8 sec for a heart rate of 70)

v = Q / xs area
velocity is lowest in vessels with greatest total xs area
P = ρgh
effect of pressure gradient (P) : (Q ) α Pi – Po
effect of tube length (L) : Q 1/α L
effect of vessel radius : Q α r 4
effect of fluid viscosity (η) Q 1/ α η

series resisters are cumulative
parallel resisters are summed as reciprocals
.viscosity (η) α hematocrit

rt. & lt.coronary arteries branch from aorta just beyond aortic valve
a. lt. coronary branches into circumflex & ant. interventricular (b/t lt & rt ventricles) arteries
b. rt. coronary...

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