Physiology of Action Potentials

Action Potential

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

Characteristics of an Action Potential

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

Sodium Ion Channels

• 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.

Refractory Period

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

Depolarization Phase

• 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

Overview

• 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

Steps of Neurotransmission

• 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

Neurotransmitters

• 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

Regulation of Neurotransmission

• 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

This quiz assesses knowledge of action potentials, including their primary function, characteristics, and ion channels. It also covers the refractory period and depolarization phase.