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Nervous System 2

Terms in this set (28)

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