Synaptic Transmission and Neural Integration

Vocabulary flashcards covering key terms and definitions related to synaptic transmission and neural integration, including electrical and chemical synapses, neurotransmitter release, and postsynaptic potentials.

Synapses

Functional association of a neuron with another neuron or with effector organs (muscle or gland).

Electrical Synapses

Synapses characterized by direct transfer of action potentials between neurons linked by gap junctions, allowing rapid, synchronous, and bidirectional communication.

Chemical Synapses

Synapses that involve a presynaptic neuron, a synaptic cleft, and a postsynaptic neuron, allowing unidirectional communication via neurotransmitters.

Presynaptic Neuron

The neuron that releases neurotransmitters into the synaptic cleft.

Synaptic Cleft

The space (30–50 nm wide) between the presynaptic and postsynaptic neurons in a chemical synapse.

Postsynaptic Neuron

The neuron that receives neurotransmitters and responds to them at a chemical synapse.

Axodendritic Synapse

A type of chemical synapse where the axon of one neuron synapses with a dendrite of another neuron.

Axosomatic Synapse

A type of chemical synapse where the axon of one neuron synapses with the cell body (soma) of another neuron.

Axoaxonic Synapse

A type of chemical synapse where the axon of one neuron synapses with the axon of another neuron.

Dendrodendritic Synapse

A type of chemical synapse where the dendrite of one neuron synapses with the dendrite of another neuron.

Neurotransmitter

Chemical messengers released from presynaptic axon terminals that diffuse across the synaptic cleft and bind to receptors on the postsynaptic neuron.

Voltage-gated Ca2+ channels

Channels on the presynaptic axon terminal that open in response to an action potential, allowing Ca2+ entry to trigger neurotransmitter release.

Synaptic Delay

The time of 0.5–5 msec between the arrival of an action potential and the change in postsynaptic membrane potential, due to Ca2+ entry, vesicle docking, and neurotransmitter release.

Channel-linked (Ionotropic) Receptors

Ligand-gated channels on the postsynaptic membrane that, when bound by a neurotransmitter, cause a fast change in membrane potential.

G protein–coupled (Metabotropic) Receptors

Receptors on the postsynaptic membrane that, when bound by a neurotransmitter, induce slow-acting responses, either through direct coupling or via a second messenger system.

Postsynaptic Potential (PSP)

A graded potential, or change in membrane potential, in the postsynaptic cell in response to receptor-neurotransmitter binding.

Excitatory Postsynaptic Potential (EPSP)

A depolarizing change in the postsynaptic membrane potential, which makes the neuron more likely to fire an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A hyperpolarizing change or membrane stabilization in the postsynaptic membrane potential, which makes the neuron less likely to fire an action potential.

Fast EPSP

An EPSP resulting from the opening of cation channels (permeable to Na+ and K+), causing a rapid and short-duration depolarization.

Slow EPSP

An EPSP resulting from the activation of a metabotropic receptor and a G protein, leading to the closure of K+ channels and a longer-duration depolarization.

Fast IPSP (K+ channel)

An IPSP resulting from the opening of K+ channels, causing K+ to leak out and leading to hyperpolarization.

Fast IPSP (Cl- channel, with ATPase pump)

An IPSP resulting from the opening of Cl- channels in cells with a Cl- ATPase pump, causing Cl- to diffuse in and leading to hyperpolarization.

Fast IPSP (Cl- channel, with leak channels)

An IPSP resulting from the opening of Cl- channels in cells at equilibrium with Cl- leak channels, causing Cl- to diffuse in and leading to membrane stabilization rather than hyperpolarization.