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.

1. Electrical synapses use connexons for direct current flow.
   • Direct, passive flow of electrical current.
2. 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 * 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