4. Action potential Flashcards
What can measure the neuron signalling? (Action potentials psychobiology)
Oscilloscope
What is shown through a concentration gradient? (Action potentials psychobiology)
Ions of a higher concentration pulled toward a lower concentration
What is shown through an electrical gradient? (Action potentials psychobiology)
Ions of a positive charge are pulled towards those of a negative charge
What does the transmembrane voltage force and what will this lead to? (Action potentials psychobiology)
Counterbalance
No net ion flow across the membrane
If a cell is permeable to more than one ion, what is the cells potential measured by? (Action potentials psychobiology)
Goldmann-Hodgkin-Katz equation
What 4 factors contribute to resting membrane potential? (Action potentials psychobiology)
- Selective permeability
- Potassium gradients
- Sodium gradients
- Ion pumps
How does selective permeability affect resting membrane potential? (Action potentials psychobiology)
May be more permeable to potassium ions
How does potassium gradients affect resting membrane potential? (Action potentials psychobiology)
In the cell, potassium ion concentration is lower than outside the membrane, so potassium ions are pulled back in
How does sodium gradients affect resting membrane potential? (Action potentials psychobiology)
The membrane is slightly permeable to sodium ions which shift the resting potential from -90mV to -70mV
How does ion pumps affect resting membrane potential? (Action potentials psychobiology)
Sodium pumps move two potassium ions into the cell for every three sodium ions moved out
What is potassium equilibrium potential? (Action potentials psychobiology)
90mV
What do ion pumps help to do? (Action potentials psychobiology)
Keep the intracellular potassium concentration high
Over time, what would a graph showing membrane potential look like? (Action potentials psychobiology)
resting potential (middle flat line)
depolarisation (rapid climb)
depolarisation (rapid fall)
hyper polarisation (low climbing line)
What are the stages of action potentials? (Action potentials psychobiology)
1) Threshold potential reached
2) Depolarisation due to the opening of sodium channels
3) Depolarisation due to inactivation of sodium channels and opening of potassium channels
4) Hyper-polarisation as potassium channels are still open
What does action potential create? (Action potentials psychobiology)
A positive feedback
What does the absolute refractory period force? (Action potentials psychobiology)
One way transmission
What is the absolute refractory period? (Action potentials psychobiology)
Where a second action potential cannot be initiated, no matter how big the applied stimulus is
What is the relative refractory period? (Action potentials psychobiology)
The interval, immediately following the ARP, where a second action potential is inhibited but not impossible
What is the charging of the membrane known as? (Action potentials psychobiology)
Capacitance
How does the thickness of the membrane change the charging of it? (Action potentials psychobiology)
The thicker the membrane, the less capacitance
What does myelin do? (Action potentials psychobiology)
Reduces the charge loss across the axon membrane by decreasing its capacitance
