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 Synaptic vesicles in presynaptic terminal
Function	Direct flow of electrical current Current sourced from local potential difference	Neurotransmitters facilitate communication as chemical messengers
Key Characteristics	Permits passive electrical current flow Influenced by presynaptic action potential	Presence of neurotransmitters in synaptic vesicles Acts through specialized receptors on postsynaptic cell