Answers | Latest Update 2026/2027 |
Graded A+ |
depolarization - answer-- inside of cell becomes positive, outside
b b b b b b b b
bnegative b
- contraction
b
- na+ channel opens
b b b b
- ELECTRICAL
b
repolarization - answer-movement of cells = inside is negative again
b b b b b b b b b b
- na+ channels close, k+ channels open
b b b b b b b
- MECHANICAL
b
refractory period - answer-per of time where cardiac cells cannot
b b b b b b b b b
brespond to stimulus b b
absolute refractory period - answer-beginning of qrs to peak of t wave
b b b b b b b b b b b
relative refractory (vulnerable per of repolarization) - answer-- cardiac
b b b b b b b b
bcells have repolarized enough to respond to strong stimulus
b b b b b b b b b
- during this per a strong stimulus may overtake the pacemaker of the
b b b b b b b b b b b b
bheart b
- ex. PVC during vulnerable period may turn into vtach or torsades
b b b b b b b b b b b b
- prolonged QT interval inc possibility
b b b b b
causes of prolonged qt intervals - answer-haldol, bradycardia,
b b b b b b b
hypokalemia
b
,automaticity - answer-ability of pacemaker cells to initiate electrical
b b b b b b b b
impulse
b
excitability - answer-ability of muscle cells to respond to outside
b b b b b b b b b
stimulus
b
conductivity - answer-ability to recieve electrical stimulus and conduct
b b b b b b b b
impulse to adjacent cells
b b b b
contraction - answer-cardiac cells shorten = muscular contraction in
b b b b b b b b
response to electrical stimulus
b b b b
sa node - answer-- primary pacemaker of heart
b b b b b b b b
- 60-90 bpm
b b
av node - answer-delay = atrial contraction + ventricular filling
b b b b b b b b b b
- 40-60 bpm
b b
bundle of his - answer-ability to self initiate electrical activity
b b b b b b b b b b
- 40-60 bpm
b b
purkinje fibers - answer-network of fibers that carry electrical impulse
b b b b b b b b b
bto ventricular muscle cells
b b b b
- 20-40 bpm
b b
NSR b
Brady b
Tachy
SVT b
Junctional b
Ventricular rhythm - answer-NSR 60-100 b b b b
Brady 40-60 b
Tachy >100 b
SVT >150 b
Junctional 40-60 b
, Ventricular rhythm 20 - 40 b b b b
PR interval - answer-0.12-0.20
b b b
beginning of p to beginning of qrs b b b b b b
qrs interval - answer-< 0.12
b b b b
beginning of q to end of s b b b b b b
p wave b b
qrs wave b
t wave - answer-- (p) atrial depolarization
b b b b b b b
- (qrs) ventricular depolarization
b b b b
- (t) ventricular repolarization
b b b
qt interval - answer-beginning of q to end of t
b b b b b b b b b b
- heart rate dependent
b b b
is rhythm regular or irregular - answer-measure interval between R
b b b b b b b b b
bwaves
ventricular rate - answer-- count # of qrs complexesb b b b b b b b
atrial rate - answer-- count # of p waves
b b b b b b b b
causes of bradycardia - answer-- vagal
b b b b b b
- dig, beta blockers
b b b b
- compensatory response in acute MI
b b b b b b
- ischemic heart disease
b b b b
- sick sinus. synd
b b b
- inc intracranial pressure
b b b
bradycardia symptoms - answer-hypotension, AMS, signs of shock,
b b b b b b b
ischemic chest discomfort, HF
b b b b