 | Term | Definition |
| |
action potential |
the sequence of electrical changes when a nerve cell membrane is exposed to a stimulus that exceeds its threshhold |
| |
autonomic nervous system |
portion of nervous system that controls the actions of the viscera |
| |
axon |
a nerve fiber that conducts a nerve impulse away from a neuron cell body |
| |
central nervous system |
portion of nervous system that consists of the brain and spinal cord |
| |
chromatophilic substances |
membranous sacs within cytoplasm of nerve cells that have ribosomes attached to their surfaces |
| |
convergence |
nerve impulses arrive at the same neuron |
| |
dendrite |
nerve fiber that transmits impulses toward a neuron cell body |
| |
divergence |
a spreading apart |
| |
effector |
a muscle of gland that responds to stimulaton |
| |
facilitation |
subthreshold stimulation of a neuron makes it more responsive to further stimulation |
| |
ganglion |
a mass of neuron cell bodies, usually outside the central nervous system |
| |
myelin |
fatty material that forms a sheathlike coverin garound some nerve fibers |
| |
neurilemma |
sheath formed from Schwann cells on the outside of some nerve fibers |
| |
neurotransmitter |
chemical that an axon end secretes to stimulate a muscle fiber to contract or a neuron to fire an impulse |
| |
parasympathetic nervous system |
portion of the autonomic nervous system that arises from brain and sacral region of the spinal cord |
| |
peripheral nervous system |
the portions of the nervous system outside the central nervous system |
| |
plexus |
a network of interlaced nerves or blood vessels |
| |
reflex |
a rapid, automatic response to a stimulus |
| |
sensory receptor |
a specialized structure associated with the peripheral end of a sensory neuron specific to detecting a particular sensation and triggering a nerve impulse in response, which is transmitted to the central nervous system |
| |
somatic nervous system |
motor pathways of peripheral nervous system that lead to the skin and skeletal muscles |
| |
sympathetic nervous system |
portion of the autonomic nervous system that arises from the thoracic and lumbar regions of the spinal cord |
| |
synapse |
the junction between the axon of one neuron and the dendrite or cell body of another neuron |
