Synaptic Transmission

Introduction

• Neuroscience Topic: Synaptic transmission
• Definition: Communication between neurons at a synapse

Synapse

• Structure: Specialized area where two neurons approach each other closely
• Components:
  • Synaptic Cleft: Microscopically small space (< 40 nm wide)
  • Not physically connected
  • Comparison: Human hair is ~75,000 nm

Neurons

• Presynaptic Neuron: Initiates the signal
• Postsynaptic Neuron: Receives the signal

Neurotransmitters

• Location: Packaged in vesicles within the presynaptic neuron
• Contents: Thousands of neurotransmitter molecules per vesicle

Action Potential

• Process:
  • Electrical signal excites the presynaptic neuron
  • Vesicles fuse with the presynaptic membrane
  • Release of neurotransmitters into the synaptic cleft

Interaction with Postsynaptic Neuron

• Binding: Neurotransmitters bind to receptors on the postsynaptic membrane
• Result:
  • May increase likelihood of postsynaptic cell firing an action potential
  • May decrease likelihood

Clearing Neurotransmitters

• Methods:
  • Diffusion: Neurotransmitter molecules drift away
  • Reuptake: Neurotransmitter taken back into presynaptic neuron
    • Recycled and reused
  • Enzymatic Breakdown: Enzymes break down neurotransmitters in the cleft
    • Components sent back to presynaptic neuron for recycling

Conclusion

• Synaptic transmission is a key process in neuronal communication, involving release, binding, and clearance of neurotransmitters to propagate signals between neurons.