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Summary Human Anatomy and Physiology

Course
- Human Anatomy and Physiology
- Bianca Brundel
- 2019 - 2020
- Vrije Universiteit Amsterdam
- Biomedische Wetenschappen
181 Flashcards & Notes
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A snapshot of the summary - Human Anatomy and Physiology

  • 1. Physiology heart

  • How is the membrane potential determined?
    • Concentration differences
    • Permeability to ions
  • If you look at this graph, what happens at which points?
    0: Na+ channels open, this starts depolarisation (inside of the membrane gets positive)
    2: Ca2+ channels open, this starts repolarisation (inside of the membrane gets more positive)
    3:  K+ channels open (inside of the membrane gets negative)
    4: Na+ and Ca2+ come to the inside of the membrane from adjacent cells
  • By what is the heart rate determined?
    • Resting membrane potential of SA node cell
    • Velocity of depolarisation: slope of the prepotential
  • What determines the slope of the prepotential?
    Na+
  • What happens to the prepotential slope if you increase the heart rate? And how can the heart rate be increased?
    (Nor)adrenaline activates the sympathetic NS and causes more Na+/Ca2+ to move into the cell, giving a smaller prepotential slope.
  • What happens to the prepotential slope if you decrease the heart rate? And how can the heart rate be decreased?
    Acetylcholine activates the parasympathetic NS and caused the K+ channels to remain open, this results in a bigger prepotential slope.
  • What is the refractory period? Why do you need this?
    The period in which cells are inexcitable (Na+ channels are not reset). You need this in order for cells not to be overstimulated.
  • What is the difference in absolute and relative refractory period?
    During the absolute refractory period it is ABSOLUTELY impossible to have a new action potential. During the relative refractory period a new action potential is inhibited but not impossible.
  • What initiates contraction?
    Ca2+ binding to myofilament
  • Describe a single heart beat at cellular level.
    • Electrical signal from neighbouring cell (CM, SA node, conduction system)
    • Action potential
      • Na+ influx
      • Ca+ influx
      • K+ influx
    • Ca2+ induced Ca2+ release (CICR)
    • Ca2+ binding to myofilaments
    • Power stroke --> cell shortening
    • Ca2+ release from myofilaments
    • Reuptake in SR --> relaxation
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