action potential to contraction in myocytes Flashcards
what causes eletrical potential across membrane
ions
myocyte resting pot
-85mV
how do APs vary between differen cells
number and type of ion channels
how does Na channels change in purkinje vs. His
more Na channel as go down - faster propagation of signal
how do diff. ion channel affect the AP
different refractory periods, pleateau, etc.
what happens to start action potential
Na open, Ca open along the way
what happens at top of AP
Na close
what is Na threshold
-55mV
what happens in plateau
Ca open, and fast K close
what happens in repolarization
Ca close, slow K open
what is Ca channel threshold
-45mV
what leads to the refractory period
Na channels closing and not opening until -85
what phase of AP is affected in long QT syndrome
repolarization
what is P wave
atrial contraction
what is Q wave
dip as travels down His
what is R wave
entrance into purkinjes (early vent.)
what is S wave
late vent depolarization
what is sinus rhythm
heart rate
normal HR
60-100bpm
what is RR interval
heart rate
what is PR interval
time of AV nodal conduction
what is QRS interval/duration
time to depolarize heart
what is QT interval
depolarization of ventricle
what could cause QRS interval lengthing (2)
- large heart
2. blocks
steps for an AP to create a contraction
- AP comes in
- L-type channels open
- Ca comes in
- activated ryanadine receptor
- RY gives Ca sparks
- summed sparks give Ca signal
- Ca troponin binding allows myosin to attach
when does relaxation occur
what Ca unbinds
what is important about short refractory period in skeletal muscle
allows mulitple contraction to build to eventual tetanus
what is the ratio for muscle contraction to AP in cardiac muscle
almost the same, so can’t get contraction on top of each other
