Electrical Signaling Flashcards
____ ____ are the vocabulary of the nervous system
Electrical signals
____ signals are how ____ is transmitted from cell to cell
Chemical; information
Membrane potential
An electrical-potential difference across the membrane
Characteristic resting membrane is in the range of ____mV to ____mV, making the typical to be ____mV
-50; -90; -70
The inside of the cell is more ____ relative to the outside
Negative
Forces influencing ion distribution between in and out of a cell
Diffusion force and electrostatic force
Diffusion force is founded on a ____ gradient, in which molecules move from ____ to ____ of the concentration gradient to achieve ____
Chemical; High; Low; Equilibrium
Electrostatic force is on a ____ gradient, in which ____ charges repel and ____ charges attract
Electrical; like; opposite
Equilibrium potential
Potential at which opposing forces reach equilibrium
Na+/K+ pump (Na+/K+ ATP-ase) moves ____ Na+ out for ____ K+ in
3; 2
Concentration of ions & polymers outside of cell
- Na+: Many
- K+: Few
- Cl-: Many
- Ca2+: Many
- Proteins: Few
Concentrations of ions & polymers inside of cell
- Na+: Few
- K+: Many
- Cl-: Few
- Ca2+: Few
- Proteins: Many
Hyperpolarization of a neuron is due to an ____ of K+ ions and an ____ of Cl- ions, making the inside of cell more ____, resulting in a ____ in voltage
Efflux; Influx; Negative; Decrease
Depolarization of a cell is due to an ____ of Na+ through ____ ____, making the inside of cell more ____, resulting in an ____ in voltage
Influx; Na+ Channels; Positive; Increase
Types of sub threshold responses
IPSP (Inhibitory postsynaptic potential) & EPSP (Excitatory postsynaptic potential)
IPSP (Inhibitory postsynaptic potential)
- Produces a small hyperpolarization, pushes the cell away from the threshold
- Typically result from Cl- ions entering the cell / K+ ions leaving the cell
EPSP (Excitatory postsynaptic potential)
- Produces a small local depolarization, pushes the cell closer to the threshold
- Typically result from positive ions entering the cell (ex. Na+), making the inside more positive
Action potential
Brief but large changes in membrane potential
Action potentials are triggered when a ____ ____ ____ is reached, which involves the triggering of ____-gated channels
Threshold membrane potential; Voltage
Membrane potential returns to its baseline when ____-gated ____ and ____ channels are ____ and the ____ ____ helps restore ion balance
Voltage; Na+; K+; Na+/K+ pump
Axon hillock
A region in the axon densely packed with voltage-gated Na+ channels, also where action potentials originate from
Absolute refractory period
- Voltage-gated Na+ channels open (inactivated)
- Voltage-gated K+ channels are closed
Relative refractory period
- Voltage-gated Na+ channels are closing and re-activating
- Voltage-gated K+ channels are opened and slowly closing
Action potential is ____ or ____: only when the threshold is reached can the action potential be fired
All; None
Because of the refractory periods, there is ~____ msec limit on how frequently APs can occur
* Firing rate max is ~____/sec
5; 200
Refractory periods prevent the AP from ____ ____
Reversing direction
Speed of transmission of AP depends on the size of the ____: The larger it is, the ____ it takes to transmit the information
Axon; Longer
Saltatory conduction gives the axon the ability for…
- Faster conduction
- Less metabolic “cost”
The Na+/K+ pump locate between the ____ ____ on an axon, where it is named the ____ ____ ____
Myelin sheath; Node of Ranvier
The Summation Mechanism of Axons
- If the overall sum of IPSPs and EPSPs can sufficiently depolarize the cell at the axon hillock, an action potential will occur
Temporal summation
The summing of potentials that arrive at the axon hillock at different TIMES
- The closer together they arrive, the greater the summation
Spatial summation
Summing of potentials that come from different PARTS of the cell
- The closer the synapses are to the axon hillock, the greater the summation
Neuromuscular junction
a synaptic connection between the terminal end of a motor nerve and a muscle
Types of neuron-neuron synapses
- Axo-dendric (axon to dendrite)
- Axo-somatic (axon to soma)
- Axo-axonic (axon to axon — mediates the effect of membrane potential from other neuron)
- Dendro-dendritic (dendrite to dendrite)
Gate 1 (voltage-gated Na+ channels)
Activation=voltage sensitive
Gate 2 (Voltage-gated Na+ channels)
Inactivation=Voltage insensitive
Subcategories of absolute refractory period
Depolarizing; Repolarizing
The ____ of ____ ____ is perceived as pain
Inflammation; trigeminal nerves
____ synapses are the vast MINORITY of synapses in the ____
Electrical; Brain
Electrical synapses in synaptic communication has lined up ____ ____ that allows for ____ flow into the ____ neuron
Gap junction; Ion; Postsynaptic
(Gap junction): Depolarization in ____ ____ leads to ____ ions moving towards post-synaptic cell
Presynaptic terminal; Na+
Primary source of synaptic communication
Chemical synapses (neurotransmitters)
