Intro to Psychology: Neurons, Action Potentials, and Synaptic Transmission

Comprehensive vocabulary flashcards covering the anatomical structure of neurons and glia, resting and action potentials, ion movements, synaptic transmission mechanisms, postsynaptic potentials, and neural network organization.

Stevan Pinker

Psychologist noted for asserting that the supposedly immaterial soul can be bisected with a knife, altered by chemicals, started by a sharp blow, stopped by electricity, and extinguished by insufficient oxygen.

Neuron

A cell specialized for communication within the nervous system.

Cell Membrane

The structural boundary that separates the inside of the neuron from the outside.

Soma

The cell body of a neuron that produces and synthesizes cellular materials.

Dendrites

Branch-like projections of a neuron that receive incoming messages and initiate electrical activity.

Axon

A neuronal fiber that conducts electrical activity away from the soma and releases chemical neurotransmitters.

Myelin Sheath

An insulating layer covering the axon that speeds up electrical activity and transmission, making information transfer more efficient.

Glial Cells

Cells typically smaller than neurons that provide nutrition, healing, protection, and physical support, while devouring dead or damaged cells, removing debris, and modulating neuronal signaling.

Axon Terminals

Endings of an axon containing terminal buttons where chemicals are released to influence the electrical activity of adjacent neurons.

Synaptic Cleft

A microscopic, fluid-filled space separating interconnected neurons across which electrical signals cannot jump directly.

Hodgkin and Huxley (1952)

Researchers who established that the fluids inside and outside neurons consist of electrically charged particles (ions) and that a resting neuron possesses a negative internal charge.

Resting Potential

The stable, negative electrical charge of approximately $-70\,\text{milivolts}$ found inside a non-stimulated neuron, acting as a tiny battery of potential energy with a higher concentration of negative ions inside.

Action Potential

A complete, rapid, and brief reversal of electrical potential across the neuronal membrane to approximately $+40\,\text{milivolts}$, which propagates down the axon to the axon terminals.

Absolute Refractory Period

The minimum interval of time following an action potential during which another action potential cannot be initiated; serves as a foundation of brain function.

Sodium ($Na^+$) Influx

The movement of positively charged sodium ions into the neuron through dedicated channels, depolarizing the cell to threshold voltage and opening voltage-sensitive sodium channels.

Potassium ($K^+$) Efflux

The massive movement of positive potassium ions exiting the cell through dedicated potassium channels during an action potential.

Presynaptic Neuron

The neuron that sends a chemical message by releasing neurotransmitters across the synaptic cleft.

Postsynaptic Neuron

The receiving neuron with specialized receptor sites that bind neurotransmitters to produce postsynaptic electrical changes.

Postsynaptic Potential (PSP)

A graded voltage change occurring at the receptive site of a postsynaptic neuron that alters the probability of that neuron firing, rather than operating as an all-or-nothing event.

Excitatory PSP (EPSP)

A positive voltage shift that causes depolarization of the neuron, making the generation of an action potential more likely.

Inhibitory PSP (IPSP)

A negative voltage shift that causes hyperpolarization of the neuron, making the generation of an action potential less likely.

Deactivation

The step in synaptic transmission wherein released neurotransmitters are destroyed and inactivated by an enzyme.

Auto-Receptor Activation

The phase in synaptic transmission during which released neurotransmitters bind to receptor sites located on the releasing (presynaptic) neuron.

Reuptake

The process by which excess neurotransmitter molecules remaining in the synaptic cleft are reabsorbed into the presynaptic neuron.

Degradation

The stage of synaptic transmission responsible for the elimination and breakdown of excess neurotransmitters.

Neural Networks

Interconnected assemblies of neurons that frequently fire either synchronously or sequentially to support perceptions, thoughts, and actions.

Synapse Pruning

The elimination of old synapses, occurring more frequently than the creation of new ones, which serves as a critical mechanism in the formation and strengthening of neural networks.