Chemical Synapse

What are the three types of chemical synapse targeting?

Axodendritic, axosomatic, axoaxonic.

Describe axodendritic synapses

Most common, axon to dendritic spines, spine shape affects response.

Describe axosomatic synapses

Axon to soma, typically inhibitory (GABAergic interneurons).

Describe axoaxonic synapses

Axon to axon terminal, modulates release, typically inhibitory.

What is a synaptic bouton?

The presynaptic terminal is where neurotransmitters are released, there are hundred that line the axon of one cell allowing form connections with hundreds of postsynaptic neurons at once

What are the main components of a chemical synapse?

1. Mitochondria,

2. vesicles,

3. active zone,

4. neurotransmitter,

5. postsynaptic receptor,

6. postsynaptic density.

What do mitochondria do in synapses?

Provide ATP and buffer calcium for neurotransmitter release.

What is the active zone?

Area concentrating vesicles for rapid neurotransmitter release.

What is the postsynaptic density?

Region concentrating postsynaptic receptors.

What is the vesicle life cycle?

Formation from endosomes, neurotransmitter loading, docking, priming, fusion (exocytosis), recycling.

What is synapotagmin's role?

Calcium sensor triggering vesicle fusion.

What is the SNARE complex?

vSNARE (synaptobrevin) and tSNAREs (syntaxin, SNAP25) mediating vesicle fusion.

What is MUNC18's role?

Stabilizes SNARE complex for vesicle docking.

How does botulinum toxin affect synapses?

Inhibits SNARE proteins, preventing neurotransmitter release, causing paralysis.

How does tetanus toxin affect synapses?

Cleaves synaptobrevin, inhibiting inhibitory neurons, causing spasms.

How does current flow in chemical synapses?

Action potential triggers Ca²⁺ influx, neurotransmitter release, and delayed receptor activation.

Can chemical synapses amplify signals?

Yes, based on receptor properties.

Compare speed of electrical vs. chemical synapses

Electrical: faster (no delay - instantaneous); Chemical: slower (1-5 ms).

Compare directionality of electrical vs. chemical synapses

Electrical: bidirectional; Chemical: unidirectional.

Which synapse type amplifies signals?

Chemical synapses.

What is chemical synaptic transmission?

The process where a presynaptic neuron releases neurotransmitters across a synaptic cleft to activate postsynaptic receptors, transmitting signals.

Why is chemical transmission significant in the brain?

It's the most common signaling method, allowing dynamic signal amplification and modification.

What are the four stages of chemical transmission?

1. Neurotransmitter synthesis | 2.

Storage and release |

3. Postsynaptic receptor interaction |

4. Removal from the synaptic cleft.

What is the postsynaptic density?

The postsynaptic density is a protein-dense area of the cell, visible as heavily stained in electron microscopy, composed of postsynaptic receptors and scaffolding proteins that traffic and hold the receptors in place.