Synaptic Transmission
Overview
- The human brain consists of 86 billion neurons.
- Communication among these neurons is facilitated by synapses.
Types of Synapses
Two main types: Electrical and Chemical Synapses.
- Electrical synapses use connexons for direct current flow.
- Direct, passive flow of electrical current.
- Chemical synapses use neurotransmitters for cell-to-cell communication.
- Chemical: Communication via neurotransmitter release.
Chemical Synapses and Neurotransmitters
- Over 100 different neurotransmitters identified.
- Communication process: Synthesis, packaging, release, and binding of neurotransmitters, followed by rapid removal or degradation.
| Feature | Electrical Synapses | Chemical Synapses |
|---|---|---|
| Structure | - Gap junctions<br>- Connexons enable close neuron-to-neuron links | - Larger synaptic cleft between neurons<br>- Synaptic vesicles in presynaptic terminal |
| Function | - Direct flow of electrical current<br>- Current sourced from local potential difference | - Neurotransmitters facilitate communication as chemical messengers |
| Key Characteristics | - Permits passive electrical current flow<br>- Influenced by presynaptic action potential | - Presence of neurotransmitters in synaptic vesicles<br>- Acts through specialized receptors on postsynaptic cell |