Nervous System Neurons, Nerves, and Glial cells Flashcards
neuron
individual nerve cell
stimulus
agent of change in the internal or external environment that evokes a response (light, sound, touch, pressure, or pain)
dendrites
branching fibers of a neuron
path of impulse
stimulus, dendrite, cell body, cell nucleus, axon (surrounded by myelin sheath), terminal end fibers, neurotransmitter, synapse
ganglia (ganglion)
small collections of nerve cell bodies outside the brain and spinal cord
axon
microscopic fiber that is part of a neuron and carries nervous impulse along a nerve cell
myelin sheath
fatty tissue that covers the axon. Purpose is to insulate the axon and speed transmission of the impulse
white matter
axons covered in myelin sheath
gray matter
composed of the cell bodies of neurons that appear gray because they are not covered by a myelin sheath
terminal end fibers
where the nervous impulse passes through the axon to leave the cell
synapse
space where the nervous impulse jumps from one neuron to another
neurotransmitter
chemical substance released at the end of the nerve cell. It stimulates or inhibits another cell. Acetylcholine, norepinephrine, dopamine, and serotonin
nerve
consists of many axons that travel together like strands of rope
what is the parenchyma of the nervous system?
neurons and nerves
stroma
connective and supportive tissue of an organ
what is the stromal tissue of the CNS?
glial (neuroglial) cells
What is important about glial cells?
Do not transmit impulses, and they are far more numerous than neurons and can reproduce
4 types of glial cells
astrocyte (astroglial cells), microglial cells, oligodendroglial cells (oligodendrocytes), ependymal cells
What are astrocytes?
star-like in appearance and transport water and salts between capillaries in neurons
What are microglial cells
small cells with many branching processes (dendrites). They protect neurons in response to inflammation
What are oligodendroglial cells?
have few or scanty dendrites. These cells form the myelin sheath in the CNS
What are ependymal cells?
line membranes within the brain and spinal cord where CFS is produced and circulates
blood-brain barrier (BBB)
protective separation between the blood and brain cells. Makes it difficult for substances to penetrate capillary walls and enter the brain