Physiology of Action Potentials

Study Notes

The primary function of an action potential is to transmit information from one location to another within a neuron.

An action potential is NOT a gradual change in membrane potential, but rather a rapid, all-or-nothing response.

The role of sodium ion channels in an action potential is to rapidly open and allow a rapid influx of sodium ions into the cell, causing depolarization.

The term for the period during which an action potential cannot be triggered again is the refractory period.

The result of the depolarization phase of an action potential is a rapid increase in the positive charge inside the cell, causing the membrane potential to become less negative.

Neurotransmission is the process of communication between neurons through synapses
It involves the release of neurotransmitters from the terminal end of one neuron, which then bind to receptors on adjacent neurons

Neurotransmitters are synthesized in the neuron and packaged into synaptic vesicles
Action potential triggers the release of neurotransmitters from synaptic vesicles into the synapse
Neurotransmitters bind to specific receptors on adjacent neurons
Binding of neurotransmitters to receptors triggers a series of chemical reactions that can either excite or inhibit the postsynaptic neuron
Excess neurotransmitters are either broken down by enzymes or taken back up by the neuron through reuptake

Excitatory neurotransmitters increase the likelihood of an action potential in the postsynaptic neuron
Examples of excitatory neurotransmitters: Glutamate, Aspartate
Inhibitory neurotransmitters decrease the likelihood of an action potential in the postsynaptic neuron
Examples of inhibitory neurotransmitters: GABA, Glycine
Modulatory neurotransmitters modify the strength or duration of synaptic transmission
Examples of modulatory neurotransmitters: Dopamine, Serotonin, Acetylcholine

Synaptic plasticity is the strengthening or weakening of synaptic connections based on experience
Neurotransmitter receptors can be modified or changed in response to experience or environmental factors
Neurotrophic factors are proteins that promote the growth and survival of neurons, and can influence neurotransmission