AHN 568 Unit 1 Exam Questions and
Answers
Sinoatrial Node (SA node)
Rate?
Location & Area of intervention?
EKG? - ANSWER-Natural pacemaker of the heart
Rate: 60-100 bpm
Location: Upper portion posterior portion of the Right Atrium near superior vena cava
EKG: represented as the P wave
Atri...
Peak positive charge; K+ closes, Cl- enters to slow channels, slow Ca2+ channels open
Phase 2 - ANSWER✔✔-Phase 2 Plateau
Opening of voltage gated slow Ca2+ channels and closing of some K+, some Na+ enters to maintain;
membrane potential is maintained or plateaued
Phase 3 - ANSWER✔✔-Phase 3 Re-polarization
Opening of voltage-gated K+ channels and closing of Ca2+ channels; K+ moves from ICF to ECF
Refractory periods - ANSWER✔✔-time from phase 0 until the repolarization of a myocyte or when
enough Na+ have recovered
Absolute refractory periods - ANSWER✔✔-occurs with the early part of the T-wave when most of the
ventricle is depolarized and is "refractory" to new stimuli
Relative refractory periods - ANSWER✔✔-occurs towards the end of the T-wave when most ventricular
cells are repolarized and vulnerable to new stimuli; can lead to VT if PVC lands during this time
Refractory = resistant
Normal P Wave - ANSWER✔✔-Measures: 0.5 - 2.5mm high
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