Synaptic Transmission: How Neurons Communicate

Overview

• Neurotransmission: Also known as synaptic transmission, involves transfer of biological information between neurons.
• Synapse: The site where transmission occurs, involving a pre-synaptic neuron (sending information) and a post-synaptic neuron (receiving information).
  • Synaptic Cleft: Small gap between neurons where transmission takes place.

Process of Synaptic Transmission

1. Action Potential Arrival
   • Initiates the process at the axon terminal of the pre-synaptic cell.
2. Calcium Channels Activation
   • Voltage-gated calcium channels open in response to the action potential.
   • Calcium ions, more abundant outside the cell, flow into the cell's interior.
   • Calcium plays a crucial role in initiating vesicle-membrane fusion.
3. Exocytosis of Neurotransmitters
   • Synaptic vesicles containing neurotransmitters fuse with the terminal membrane.
   • Neurotransmitters are released into the synaptic cleft.

Types of Neurotransmitters

• Amino Acids: Glycine, Glutamic Acid, GABA
• Others: Dopamine, Acetylcholine
• Note: Many types exist with various functions.

Interaction with Post-Synaptic Cell

• Diffusion: Neurotransmitters cross the cleft and bind to receptors on the post-synaptic neuron.
• Receptor Activation: Determines outcome:
  • Ion Channel Opening/Closing: Alters electrical state of post-synaptic cell.
  • Activation/Inhibition: Can either trigger or inhibit action potentials in the post-synaptic cell.

Neurotransmitter Receptor Dynamics

• Temporary Binding: Neurotransmitters bind briefly to receptors.
• Ion Channel State: Returns to resting once neurotransmitters detach.
• Clearance: Neurotransmitters are enzymatically degraded or reabsorbed by the axon terminal.
  • Important for medication applications.

Additional Information

• For more on neuron structures and functions, further resources are suggested.
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