Nerve Impulse Flashcards
(21 cards)
What is the resting membrane potential?
-70mV achived by the Sodium-potassium pump (3 Na+ out for 2 K+ in) during this, Potassium (ungated) channels opened
What is hyperpolarization?
Inside more negative
What is depolarization?
Inside more positive
What does polar mean?
A structure having an uneven distribution of electron density
What are Lingad-gated ion channels?
Found at dendrites and open/close when bound to neurotransmitters
What are Voltage-gated ion channels?
Found in axons and Open/close when membrane potential changes
What are action potentials?
Triggered by a stimulus strong enough to produce a depolarization to threshold
What is the all or non phenomenone?
Neurons either fire maximally
or not at all.
AP Generation #1
When membrane is depolarized, Na+ voltage-gated channels open
AP Generation #2
Na+ influx causes further depolarization, opening more Na+ voltage-gated channels
AP Generation #3
Na+ voltage-gated channels close
AP Generation #4
K+ voltage-gated channels open, allowing efflux of K+, known as repolarization.
AP Generation #5
K+ voltage-gated channels open longer than needed, creating an “undershoot”
What does AP Gen #5 prevent?
second stimulus from depolarizing
membrane.aka the refractory period
What is a synapse?
space between two neurons or between a neuron and an effector
What is a presynaptic neuron?
carries impulse toward synapse
What is a postsynaptic neuron?
carries impulse away from
synapse.
Synaptic Transmission
Impulse down axon–NTs released from presynaptic axonal end plates–NTs diffuse across synaptic cleft–depolarizes
postsynaptic dendrite
Excitatory NTs on Postsynaptic Membrane
Opens Na+ channels and Causes depolarization
Inhibitory NTs on Postsynaptic Membrane
More permeable to K+ and Causes hyperpolarization
What is summation?
Effect produced by the
accumulation of NTs from two or more neurons.
