Functional groups of neurons that process and ingrate information.
Sodium-potassium (Na+-K+) pump
A primary active transport system that simultaneously drives Na+ out of the cell against a s steep gradient and pumps K+ back in. Also called Na+-K+ ATPase.
Involuntary nervous system
The autonomic nervous system
Enzyme present at the neuromuscular junction and synapses that degrades acetylcholine and terminates its action.
Peripheral nervous system (PNS)
Portion of the nervous system consisting of nerves and ganglia that lie outside of the brain and spinal cord.
Nerve growth factor (NGF)
Protein that promotes survival and development of neurons; secreted by their target cells and many other cell types.
Branching neuron process that serves as a receptive, or input, region; transmits an electrical signal toward the cell body.
function junction or point of close contact between two neurons or between a neuron and an effector cell.
(1) control center of a cell; contains genetic material; (2) clusters of nerve cell bodies in the CNS.
Ability to transmit an electrical impulse.
Accumulation of effects those of muscular, sensory, or mental stimuli.
A type of CNS supporting cell that composes myelin sheaths.
Non-excitable cells of neural tissue that support, protect, and insulate, the neurons. See Neuroglia..
Neuron process that carries impulses away from the nerve cell body; efferent process; the conducting portion of a nerve cell.
Axon terminals (terminal boutons)
The bulbous distal endings of the terminal branches of an axon.
A type of CNS supporting cell; can transform into phagocytes in areas of neural damage or inflammation.
fluid filled space at a synapse.
Multiple sclerosis (MS)
Demyelinating disorder of the CNS; causing hardened patches (sclerosis) in the brain and spinal cord.
Afferent (sensory) nerve
Nerve that contains processes of sensory neurons and carries nerve impulses to the central nervous system.
Excitatory postsynaptic potential (EPSP)
Depolarizing graded potential in a postsynaptic neuron.
Automatic reaction to stimuli.
Ability to respond to stimuli.
White substance of the central nervous system; myelinated nerve fibers.
Epinephrine, norepinephrine, and dopamine; a class of amines that act as chemical transmitters.
Fast-acting control system that triggers muscle contraction or gland secretion.
Inhibitory postsynaptic potential (IPSP)
A graded potential in a postsynaptic neuron that inhibits action potential generation; usually hyperpolarizing.
Fatty insulating sheath that surrounds all but the smallest nerve fibers.
Transmission of an action potential along a myelinated fiber in which the nerve impulse appears to leap from gap to gap.
Neuron with axon and dendrite that extend from opposite sides of the cell body.
A large transient depolarization event, including polarity reversal, that is conducted along the membrane of a muscle cell or a nerve fiber.
Neuron in which embryological fusion of the two processes leaves only one process extending from the cell body.
Interneuron (association neuron)
Nerve cell located between motor and sensory neurons that shuttles signals through CNS pathways where integration occurs.
Time required for an impulse to cross a synapse between two neurons.
Resting membrane potential
Resting membrane potential: the voltage that exists across the plasma membrane during the resting state of an excitable cell; ranges from -90 to -20 millivolts depending on cell type.
A type of supporting cell in the PNS; forms myelin sheaths and is vital to peripheral nerve fiber regeneration.
Branching ends of an axon that allow it to form many axon terminals; telodendria.
A self-propagating wave of depolarization; also called an action potential.
Non-excitable cells of neural tissue that support, protect, and insulate the neurons; glial cells.
The plasma membrane of an axon
Carrying away or away from, especially a nerve fiber that carries impulses away from the central nervous system.
A local change in membrane potential that varies directly with the strength of the stimulus, declines with distance.
Chemical messenger released by neurons that may, upon binding to receptors of neurons or effector cells, stimulate or inhibit those neurons or effector cells.
A class of neurotransmitters including beta endorphins and enkephalins (which act as euphorics and reduce perception of pain) and gut-brain peptides.
Nitric oxide (NO)
A gaseous chemical messenger; diverse functions include participation in memory formation in the brain, and causing vasodilation throughout the body.
Supply of nerves to a body part.
Carrying to or toward a center.
Loss of a state of polarity; loss or reduction of negative membrane potential.
A type of CNS supporting cell; assists in exchanges between blood capillaries and neurons.
The process by which the nervous system processes and interprets sensory input and makes decisions about what should be done at each moment.
Central nervous system (CNS)
Brain and spinal cord.
Voluntary nervous system
The somatic nervous system.
Chemical transmitter substance released by some nerve endings.
An increase in membrane potential in which the membrane becomes more negative than resting membrane potential.
The division of the autonomic nervous system that oversees digestion, elimination, and glandular function; the resting and digesting subdivision.
Another term for unipolar neuron.
A type of CNS supporting cell; lines the central cavities of the brain and spinal cord.
The division of the autonomic nervous system that prepares the body for activity or to cope with some stressor (danger, excitement, etc..); the fight. fright, and flight subdivision.
Relative refractory period
Follows the absolute refractory period interval when a threshold for action potential stimulation is markedly elevated.
A bundle of axons in the peripheral nervous system.
Somatic nervous system
division of the peripheral nervous system that provides the motor innervation of skeletal muscles; also called the voluntary nervous system.
Absolute refractory period
Period following stimulation during which no additional action potential can be evoked.
Small membranous sacs containing neurotransmitter.
Neurons with three or more processes; most common neuron type in the CNS.
Neuron (nerve cell)
Cell of the nervous system specialized to generate and transmit electrical signals (action potentials and graded potentials).
Axon of a neuron
To combined difference in concentration and charge; influences the distribution of diffusion of ions
Neuron cell body
The biosynthetic center of a neuron; also called the perikaryon, or soma.