Difference between Electrical and Chemical Synapses

Introduction

• A synapse connects two neurons or a neuron with a target or effector cell, such as a muscle cell. It facilitates the transmission of electrical or chemical impulses.
• The synapse forms a connection between presynaptic and postsynaptic neurons. The neuromuscular junction connects a neuron with a muscle.
• A synapse transmits nerve impulses from one neuron’s axon terminal to the dendrites of the next neuron. It could be electrical or chemical in nature.

Table of Contents

• Electrical Synapse
• Chemical Synapse
• Functional Connections between Electrical and Chemical Synapses
• Difference between Electrical and Chemical Synapses
• Frequently Asked Questions – FAQs

Electrical Synapse

• Electrical synapses are faster compared to chemical synapses.
• An electric signal transmission across the electrical synapse is identical to the conduction of impulse in an axon because these gap junctions enable immediate ion passage.
• Gap junctions are formed when presynaptic and postsynaptic neurons are close together. Protein channels form a physical link between pre and postsynaptic neurons at the gap junction.
• Electrical synapses are less adaptable than chemical synapses since they can’t switch from excitatory to inhibitory signals.
• Some lower invertebrates have it. It is present between glial cells in humans.
• The presynaptic and postsynaptic membranes are relatively close together in an electrical synapse, and channel proteins generate gap junctions that physically connect them.

Chemical Synapse

• Chemical synapses are much more prevalent. Neurotransmitters are responsible for the transfer of nerve signals through chemical synapses.
• The synaptic cleft is a fluid-filled gap between the two neurons. A nerve impulse cannot travel from one neuron to the next.
• Synaptic vesicles from the terminal of the presynaptic neuron produce neurotransmitters at the synaptic cleft when the action potential reaches the terminals.
• Neurotransmitters bind to postsynaptic membrane receptors enabling voltage-gated channels to open, allowing ions to flow.
• The polarity of the postsynaptic membrane changes, and the electric signal is transmitted across the synapse.
• Neurotransmitters could be inhibitory or excitatory. Various cells respond to the same neurotransmitter in different ways.
• The neurotransmitter is inhibitory if there is a net influx of positively charged ions within the cell, which causes the action potential to be generated (EPSP – excitatory postsynaptic potential).
• The membrane is hyperpolarized as the membrane potential gets increasingly negative, and neurotransmitter action becomes inhibitory. They produce IPSP or inhibitory postsynaptic potential.
• Once connected to the receptor, neurotransmitters are either worked on by enzymes or transferred back and recycled to end the signal after it has been transmitted forward.

Functional Connections between Electrical and Chemical Synapses

1. Although chemical synapses are thought to be more complex anatomically and functionally than electrical synapses, new data suggests that electrical synapses are just as complex, functionally diverse, and highly changeable.
2. These two synaptic transmission modalities interact intimately, rather than working independently and providing different purposes. Synaptic transmissions are both chemical and electrical, and connections between these two types of interneuronal communication are necessary for optimal brain development and function.
3. The formation of chemical and electrical synapses, which reciprocally and dynamically govern the emergence of these two modes of transmission, appears to be crucial in developing neuronal circuits in various nervous systems (both vertebrates and invertebrates).
4. Interactions between electrical synapses are critical for the construction of neuronal circuits throughout development. Neuromodulators like dopamine and glutamatergic synapses affect the strength of electrical synapses in an activity-dependent manner.
5. Electrical and chemical synaptic interactions are also expected to have significant pathogenic consequences. Following brain damage, recapitulation of developmental connections among chemical and electrical synapses has been observed, and neurotransmitter dysregulation of electrical synapses might contribute to cognitive impairment.

Difference between Electrical Synapse and Chemical Synapse

The major difference between a chemical and an electrical synapse is that in a chemical synapse, the nerve impulse is transmitted chemically via neurotransmitters, whereas in an electrical synapse, the nerve impulse is transmitted electrically via channel proteins.

Related Links:

• Human Nervous System
• What Is the Role of Synapses in Nerve Impulses?