Chapter 1 Cont'd Flashcards
Autonomic Nervous System
Controls:
automaticity
excitability
conductivity
contractility
Sympathetic Nervous System
stimulates heart
Parasympathetic Nervous System
slows heart rate
vagus nerve (vagal)
Sinoatrial (SA) node
controlled by both PSNS and SNS
natural rate of 60-99 bpm
located in right atrium
Bachmann’s Bundle
sends impulse to left atrium
Atrioventricular (AV) node
located in right atrium
delays impulse (.12 seconds)
-allows for ventricle filling
Bundle of His
speeds up impulse to ventricles
Bundle branches
right and left branches travel along interventricular septum
left bundle branch divides into septal fascicle
Purkinje fibers
Happens twice as fast
ventricular contraction occurs, ends the signal
States of Polarization
Phase 4: Resting Phase
Phase 0: Rapid Depolarization
Phase 1: Early Repolarization
Phase 2: Plateau
Phase 3: Rapid Repolarization
Phase 4
Resting Phase
resting state
no electrical activity
Phase 0
action potential
calcium and sodium open
Phase 1
during contraction, the cell partially repolarizes
sodium close, calcium still open
Phase 2
Plateau
contraction complete, cell begins to relax
potassium out of cell
Phase 3
relaxation completed
calcium closes, potassium continues to flow out
