Electrical and Chemical
Synapses
,Distinguishing Properties of Electrical and Chemical
Synapses
,• In electrical synapses, the cytoplasms of adjacent cells are
directly connected by clusters of ion channels called gap junctions
that allow free movement of ions from the interior of one cell to the
interior of the next cell.
• Similar junctions are involved in transmittance of action potentials
from one smooth muscle fiber to the next in visceral smooth
muscle and from one cardiac muscle cell to the next in cardiac
muscle.
• Although most synapses in the brain are chemical, electrical and
chemical synapses may coexist and interact in the central nervous
system.
• The bidirectional transmission of electrical synapses permits them to
help coordinate the activities of large groups of interconnected
neurons.
• For example, electrical synapses are useful in detecting the coincidence
of simultaneous subthreshold depolarizations within a group of
interconnected neurons; this enables increased neuronal sensitivity and
promotes synchronous firing of a group of interconnected neurons.
, • Compared to chemical synapses, electrical synapses conduct nerve impulses
faster, but, unlike chemical synapses, they lack gain—the signal in the
postsynaptic neuron is the same or smaller than that of the originating neuron.
• The fundamental bases for perceiving electrical synapses comes down to the
connexons that are located in the gap junction between two neurons.
Electrical synapses are often found in neural systems that require the fastest
possible response, such as defensive reflexes.
• The simplicity of electrical synapses
results in synapses that are fast, but can
produce only simple behaviors compared
to the more complex chemical synapses.
• Because electrical synapses do not
involve neurotransmitters, electrical
neurotransmission is less modifiable than
chemical neurotransmission.
• Present throughout the CNS and have been studied specifically in the
neocortex, hippocampus, olfactory bulb, retina, and spinal cord of vertebrates.
Other examples of functional gap junctions detected in vivo are in the striatum,
cerebellum, and suprachiasmatic nucleus.
Synapses
,Distinguishing Properties of Electrical and Chemical
Synapses
,• In electrical synapses, the cytoplasms of adjacent cells are
directly connected by clusters of ion channels called gap junctions
that allow free movement of ions from the interior of one cell to the
interior of the next cell.
• Similar junctions are involved in transmittance of action potentials
from one smooth muscle fiber to the next in visceral smooth
muscle and from one cardiac muscle cell to the next in cardiac
muscle.
• Although most synapses in the brain are chemical, electrical and
chemical synapses may coexist and interact in the central nervous
system.
• The bidirectional transmission of electrical synapses permits them to
help coordinate the activities of large groups of interconnected
neurons.
• For example, electrical synapses are useful in detecting the coincidence
of simultaneous subthreshold depolarizations within a group of
interconnected neurons; this enables increased neuronal sensitivity and
promotes synchronous firing of a group of interconnected neurons.
, • Compared to chemical synapses, electrical synapses conduct nerve impulses
faster, but, unlike chemical synapses, they lack gain—the signal in the
postsynaptic neuron is the same or smaller than that of the originating neuron.
• The fundamental bases for perceiving electrical synapses comes down to the
connexons that are located in the gap junction between two neurons.
Electrical synapses are often found in neural systems that require the fastest
possible response, such as defensive reflexes.
• The simplicity of electrical synapses
results in synapses that are fast, but can
produce only simple behaviors compared
to the more complex chemical synapses.
• Because electrical synapses do not
involve neurotransmitters, electrical
neurotransmission is less modifiable than
chemical neurotransmission.
• Present throughout the CNS and have been studied specifically in the
neocortex, hippocampus, olfactory bulb, retina, and spinal cord of vertebrates.
Other examples of functional gap junctions detected in vivo are in the striatum,
cerebellum, and suprachiasmatic nucleus.
