Excitatory synapse

Excitatory Synapse

An excitatory synapse is a type of synapse that increases the likelihood of the post-synaptic neuron firing an action potential. This is achieved through the release of neurotransmitters that bind to receptors on the post-synaptic neuron, leading to a depolarization of the neuron's membrane potential.

Mechanism of Action

The process begins when an action potential reaches the pre-synaptic neuron. This triggers the opening of voltage-gated calcium channels, allowing calcium ions to flow into the neuron. The influx of calcium ions causes synaptic vesicles to fuse with the pre-synaptic membrane and release neurotransmitters into the synaptic cleft.

The neurotransmitters then diffuse across the synaptic cleft and bind to specific receptors on the post-synaptic neuron. These receptors are typically ligand-gated ion channels, which open in response to the binding of the neurotransmitter. The opening of these channels allows positively charged ions to flow into the post-synaptic neuron, causing a depolarization of the membrane potential. If this depolarization reaches the threshold potential, it will trigger an action potential in the post-synaptic neuron.

Neurotransmitters

The most common neurotransmitter involved in excitatory synapses is glutamate. Glutamate binds to a variety of receptors, including the NMDA receptor and the AMPA receptor, both of which are ligand-gated ion channels. Other neurotransmitters that can act at excitatory synapses include acetylcholine and norepinephrine.

Clinical Significance

Excitatory synapses play a crucial role in many aspects of neural function, including learning and memory. However, excessive activity at excitatory synapses can lead to neurotoxicity, contributing to the development of neurological disorders such as Alzheimer's disease and epilepsy.

See Also

• Inhibitory synapse
• Neurotransmission
• Neural plasticity

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Excitatory_synapse

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  Diagram of a synapse

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  Video of synaptic transmission

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  Histological sample of Substantia nigra in Parkinson's disease