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| Rapid increase in positive charge in a nerve fiber (axon) that travels down the fiber. Action potentials are all-or-nothing events (compare graded potential). Also called nerve impulse or spike. |
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| A long projection of a neuron that typically conducts action potentials away from the neuron's cell body. Also known as a nerve fibre. |
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| The basic structural, functional, and biological unit of all known living organisms. |
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| The core region of a cell containing the nucleus and other cell organelles. |
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| Branching extensions of the neuron’s plasma membrane that increase the surface area of the neuron and collect neuronal activity from other cells. |
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| The membrane potential at which a particular type of ion has no driving force to diffuse through the plasma membrane in either direction. At the equilibrium potential, chemical and electrical gradients are equal in magnitude. |
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| Non-neuronal cells in the nervous system that provide support and protection for neurons. Among many other functions, Glia cells are responsible for the myelination of axons. |
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| A relatively small change in membrane potential, for example by opening ligand-gated ion channels. The strength of a graded potential is given relative to the strength of stimulation (compare action potential). |
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| A group of ion channels, which open to allow ions such as Na+, K+, Ca2+, or Cl− to pass through the membrane in response to the binding of a messenger. |
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| The difference in electric potential between the interior and the exterior of a biological cell. |
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| A fatty substance that surrounds the axon of many neurons. Myelin increases the membrane resistance helping to speed the conductance of action potentials. |
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| The concept proposing that the neuron is the fundamental unit of the nervous system. Compare Reticular theory. |
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| Chemical messenger released by neurons onto a target cell with an excitatory or inhibitory effect. |
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| A type of glia cells in the central nervous system (CNS). Oligodendrocytes cells wrap around axons to form the myelin sheath (equivalent to Schwann cells). |
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| A membrane-enclosed organelle found in eukaryotic cells that contains most of the cell's genetic material. |
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| A biological membrane that separates the interior of all cells from the outside environment. The plasma membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of the cell. |
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| Referring to the neuron (or parts thereof) after the synapse with respect to the flow of information. Compare presynaptic. |
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| Changes in the membrane potential of the postsynaptic neuron of a synapse. Postsynaptic potentials are graded potentials that are either excitatory or inhibitory. |
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| The ion of the Potassium atom, which is positively charged (K+). One of the main players contributing to the membrane potential of neurons. |
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| Referring to the neuron (or parts thereof) before the synapse with respect to the flow of information. Compare postynaptic. |
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| The membrane potential in the absence of stimulation. The resting potential of neurons is typically around -70 mV (inside negative). It depends on the equilibrium potentials of contributing ions and the selective membrane permeability for these ions. |
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| An obsolete scientific theory in neurobiology that stated that the nervous system is made up of a single interlinking network. Compare Neuron doctrine. |
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| The principal glia of the peripheral nervous system (PNS). Schwann cells wrap around axons to form the myelin sheath (equivalent to Oligodendrocytes). |
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| The ion of the Sodium atom, which is positively charged (Na+). One of the main players contributing to the membrane potential of neurons. |
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| An energy consuming enzyme that pumps sodium out of cells, while pumping potassium into cells. It is essential for maintaining the resting potential (and therefore normal brain functioning). |
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| The junction between a neuron and another cell that forms the information transfer site between the two cells. |
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| Small membrane compartments that store and release neurotransmitters at the synapse. |
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| Gated membrane channels that open and close only at specific membrane potentials. Voltage-gated channels are essential for the generation of action potentials. |
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