The Science of Synapses

Introduction

• Synapse: A junction between two neurons, acting as communication links.
• Key role in the nervous system, transforming structure into function.
• Origin: Greek word meaning "to clasp or join."

Neurons and Synapses

• Human brain: 100 billion neurons, each with 1,000-10,000 synapses.
• Total synapses: 100-1,000 trillion in the brain.
• Synapses enable learning, memory, and affect psychiatric disorders.

Types of Synapses

• Electrical Synapses: Fast, direct ion current transmission through gap junctions.
  • Example: Muscle cells in the heart.
  • Pros: Speed and synchrony.
  • Cons: Lack of control, not suitable for all body functions.
• Chemical Synapses: Use neurotransmitters for signal transmission.
  • Slower but more precise and selective.

Synapse Function

• Presynaptic Neuron: Sends signals through the presynaptic terminal.
• Postsynaptic Neuron: Receives signals at the receptor region.
• Neurotransmitters diffuse across the synaptic cleft.

Transmission Process

1. Action potential activates voltage-gated calcium channels.
2. Calcium influx causes neurotransmitter release.
3. Neurotransmitter binds to receptors on the postsynaptic neuron.
4. Signal converted back to electrical form.
5. Response depends on neurotransmitter type (excitatory or inhibitory).

Neurotransmitters

• Over 100 types with various functions: mood regulation, alertness, etc.
• Short binding duration, followed by reuptake or degradation.

Impact of Drugs

• Drugs can alter neurotransmitter activity.
• Example: Cocaine blocks reuptake of dopamine, serotonin, norepinephrine.
  • Leads to temporary euphoria, but long-term imbalances and receptor loss.

Conclusion

• Synapses are critical for communication within the nervous system.
• Balance in neurotransmitter activity is essential for healthy function.

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Acknowledgments

• Supported by Logan Sanders and Dr. Linnea Boyev.
• Created by Kathleen Yale, edited by Blake DePestino, consulted by Dr. Brandon Jackson.
• Direction by Nicholas Jenkins and Michael Aranda, graphics by Thought Cafe.