N250 EXAM 1 QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
What are dysrhythmias?
disorder of electrical impulse
causes disturbance in HR, Heart rhythm, or both
CO is impaired
cellular oxygenation is also impaired
Resting potential state
cells are polarized
& ready to accept impulse
Depolarization
cells receive and respond to electrical stimulus
makes inside of cell +
repolarization
movement of charged particles
makes cell - again
(resting period)
absolute refractory period
heart cannot accept another impulse
(right after flushing toilet)
,relative refractory period
a greater than normal impulse can cause electrical disturbance
(pushing handle harder will = flush)
automaticity
ability to INITIATE a response
excitability
ability to RESPOND to an impulse
conductivity
ability to TRANSMIT an impulse
contractility
ability to respond to an electrical impulse w/ a pump action
Normal Electrical Conduction
SA Node→
AV node→
Conduction→
bundle of his→
R and L bundle branches→
Purkinje fibers
SA node (sinoatrial node)
pacemaker of the heart
rate = 60-100
P wave on ECG
,impulse moves from SA thru atrial muscle = atrial depolarization (P wave)
AV node (atrioventricular node)
PR on ECG
rate= 40-60
transitional cells cause impulse to slow down before going to ventricles
this delay allows the atria to contract and the ventricles to refill
Bundle of His
connects w/ distal portion of AV node & continues thru intraventricular septum
divides into L & R bundle branches
Purknje fibers
ends of the R & L bundle branches
responsible for rapid conduction of electrical impulses thru ventricles
leads to ventricular depolarization & ventricular contraction
P wave
atrial depolarization
PR interval
time it takes the impulse to go from SA to AV node
QRS complex
ventricular depolarization
T wave
ventricular repolarization
, prolonged QT
can result in lethal dysrhythmia
drugs that cause this:
reglan
zofran
halodol
NORMAL intervals:
PR=
QRS=
QT=
PR= 0.12-0.20
QRS= 0.04-0.10
QT= 0.36- 0.44
QT>> should not exceed 1/2 of the R to R interval
Steps of rhythm evaluation
1. HR > fast or slow?
2. rhythm > reg or irreg?
3. P wave> present/reg/similar?
4. PR interval
5. QRS
6. QT
7. ANALYZE
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
What are dysrhythmias?
disorder of electrical impulse
causes disturbance in HR, Heart rhythm, or both
CO is impaired
cellular oxygenation is also impaired
Resting potential state
cells are polarized
& ready to accept impulse
Depolarization
cells receive and respond to electrical stimulus
makes inside of cell +
repolarization
movement of charged particles
makes cell - again
(resting period)
absolute refractory period
heart cannot accept another impulse
(right after flushing toilet)
,relative refractory period
a greater than normal impulse can cause electrical disturbance
(pushing handle harder will = flush)
automaticity
ability to INITIATE a response
excitability
ability to RESPOND to an impulse
conductivity
ability to TRANSMIT an impulse
contractility
ability to respond to an electrical impulse w/ a pump action
Normal Electrical Conduction
SA Node→
AV node→
Conduction→
bundle of his→
R and L bundle branches→
Purkinje fibers
SA node (sinoatrial node)
pacemaker of the heart
rate = 60-100
P wave on ECG
,impulse moves from SA thru atrial muscle = atrial depolarization (P wave)
AV node (atrioventricular node)
PR on ECG
rate= 40-60
transitional cells cause impulse to slow down before going to ventricles
this delay allows the atria to contract and the ventricles to refill
Bundle of His
connects w/ distal portion of AV node & continues thru intraventricular septum
divides into L & R bundle branches
Purknje fibers
ends of the R & L bundle branches
responsible for rapid conduction of electrical impulses thru ventricles
leads to ventricular depolarization & ventricular contraction
P wave
atrial depolarization
PR interval
time it takes the impulse to go from SA to AV node
QRS complex
ventricular depolarization
T wave
ventricular repolarization
, prolonged QT
can result in lethal dysrhythmia
drugs that cause this:
reglan
zofran
halodol
NORMAL intervals:
PR=
QRS=
QT=
PR= 0.12-0.20
QRS= 0.04-0.10
QT= 0.36- 0.44
QT>> should not exceed 1/2 of the R to R interval
Steps of rhythm evaluation
1. HR > fast or slow?
2. rhythm > reg or irreg?
3. P wave> present/reg/similar?
4. PR interval
5. QRS
6. QT
7. ANALYZE
