lab 9 physio

intrinsic conduction system

nodal tissues; SA node, internodal tracts, AV node, bundle of His, right and left bundle branches, Purkinje fibers

primary pacemaker

sa node; 70-80 bpm; sinus rhythm

secondary pacemaker

SA node; 40-60 bpm

tertiary pacemakers

purkinje fibers; 30-40 bpm; set ventricular rate

ventricular systole

ventricular contraction that occurs after the depolarization of the ventricles

repolarization

relaxation of the heart muscle; diastole

P wave

depolarization of the atria

QRS complex

depolarization of the ventricles

T waves

repolarization of the ventricles

P-R interval

<0.2; atrial depolarization and systole

S-T segment

plateau of the AP when all of the myocardium is depolarized

Q-T interva;

0.31-0.43; ventricular depolarization through ventricular repolarization

Lead I

electrical potentials between right arm and left arm

Lead II

right arm to left leg

Lead III

records left arm to left leg

atrial flutter

rapid atrial waves (sawtooth appearance) with AV node beating to every ¾ wave it receives

atrial fibrillation

abscence of P waves that are replaced by a wavy baseline

ventricular tachycardia

widened and distorted QRS complex that obscures the P waves

ventricular fibrillation

uncontrolled contractions that do not allow the ventricles to adequately pump blood; restored by defibrillation

1st degree av block

p-r interval is greater than 0.20 seconds

second degree AV block

two or more P waves are seen before QRS is recorded

third degree/complete AV BOCK

no signlas from atria reach the ventricles