Unit 6 - Electrical Properties of Neurons Flashcards
Squid Giant Axons
Controls part of the water jet repulsion
Unmyleinated: decreases the conduction velocity potential substantially
Role of Plasma Membrane
Acts as a barrier that separates charges by keeping different ions inside or outside cell.
Ion concetrations differ between exterior/interior of cell, act as an electrical force measured in volts. (interior more negative)
Resting Potenital = -70mV
Threshold Potential
-50 mV:Critical level at which membrane potential must be depolarized in order to intimate an action potential
Voltage gated K+ Channels
“Leaking Channels”
Tend to be more open at the resting membrane potential
Action Potential
When stimulus pushes resting potential to threshold value.
Voltage gated Na+ and K+ channels open in the plasma membrane
Inward flow of Na+ changes membrane potential from negative to positive peak
Potential falls to resting value when K+ channels open
Refractory Period
Action Potentials are prevented from reversing direction
Voltage gated K+ Channels and Evolution of NS
Evolution of K+ channels with a slower opening time than Na+ channels was a key even that led to the formation of NS. If both opened at the same time they would negate each others effects.
Saltatory Conduction
In myelinated axons, ions can flow across the plasma membrane only at nodes where the myelin sheath is interrupted.
Action potentials skip node to node.
SC allows thousands of fast transmitting axons to be packed into a small diameter.
Integration of Signals
Graded Potentials:
- Neurons carry out integration by summing:
Excitatory Postsynaptic Potentials (EPSP)
Inhibitory Postsynaptic Potentials (IPSP)
Summation:
Pushes membrane potential of receiving cell toward/away from action potential
Summation
Is the addition of post synaptic potentials
Temporal: one neutron fires (time)
Spatial: two neutron fires (space)
Effects: Control behaviour and underlie complex mental processes
