type of neuron that carries messages from sensory receptors to the brain or the spinal cord; known also as afferent neurons
neurons that carry outgoing information from the central nervous system to the muscles and glands; also known as efferent neurons
neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs.
the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, they travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
enables muscle action, learning, and memory; with Alzheimer's disease, the neurons that produce it deteriorate
a neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system; excess activity of this neurotransmitter is linked to schizophrenia, and the lack of it is related to the decreased mobility and tremors of Parkinson's disease
a neurotransmitter that affects hunger, sleep, arousal, and mood; it appears in lower than normal levels in depressed persons
helps control alertness and arousal; an undersupply can depress mood; while an oversupply can lead to mania
GABA (gamma-aminobutyric acid)
a major inhibitory neurotransmitter; an undersupply linked to seizures, tremors, anxiety and insomnia
a major excitatory neurotransmitters: involved in memory. Oversupply can overstimulate brain,producing migraines or seizures (which is why some people avoid MSG (monosodium glutamate) in food
a drug that is similar enough in structure to a neurotransmitter molecule to mimic its effects (e.g., morphine mimics the action of endorphins)