Chapter 1.2 Flashcards
Resting potential
Difference in voltage in cell
Prepares neuron to respond rapidly
Concentration gradient
Difference in distribution of ions across membrane; Ion moves to even out the number of ions inside/outside the membrane
Sodium moves in; K moves out
Electrostatic gradient
Opposites attract & negative ions pulled towards positive ones
Inside of cell is negative and sodium is positive, so Na pulled in
Depolarization
Inside of cell becomes less negative
Hyperpolarization
Inside becomes more negative
Temporal summation
Sum of successive EPSP’s from a single neuron at the same TIME
Repeated stimuli over a short period of time produces stronger response
Spatial summation
Synaptic input from SEVERAL LOCATIONS can have a cumulative effect and trigger a nerve impulse
Action potential
A big stimulus beyond the threshold that produces a big response
Voltage gate
Proteins that regulate Na and K; permeability depends on voltage difference across membrane
Absolute refractory period
Period immediately following the firing of a neuron when it cannot be stimulated no matter how great a stimulus applied
Sodium channels close
Relative refractory period
Period shortly after firing of a neuron when a greater than normal stimulus can stimulate a second response
All-or-none law
The amplitude and velocity of an action potential are independent of the intensity of the stimulus as long as the stimulus reaches threshold
Propagation of the action potential
The transmission of an action potential down an axon
Begins at axon hillock and is generated and regenerated down the axon
Action potential process:
- Axon reaches threshold, Na & K channels open
- Na ions rush into axon (depolarization)
- Positive charge flows down axon and opens Na channels at each point
- At peak of AP, Na channels close
- K ions flow out
- K channels close
Saltatory conduction
Describes AP jumping from node to node
Occurs in myelinated axons
Conserves energy
More rapid
Multiple schlerosis
Immune system attacks myelin sheath, so action potentials die out between one node and the next
Causes poor motor coordination & vision impairment
Local neurons
Small neurons without an axon that exchange info only with closest neighbors
Don’t follow all-or-none law
Potential gradually decays as it travels
Post synaptic potential
Ligand-gated (chemically gates)
Decremental - dendrites farther from axon hillock lose amplitude
Goal to trigger action potential
Autoreceptors
Receptor located on presynaptic terminal of neuron
Tracks amount of neurotransmitter being fired
Flexor muscles
Draw an extremity toward trunk of body
Extensor muscles
Move an extremity away from body
Spontaneous firing rate
Action potentials triggered by synapses that are weakly or erroneously connected to neuron
Polarization/electrical gradient
A difference in the electrical charge between inside and outside of cell
