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25 terms

chapter 12 nervous tissue

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neurons
Individual cells in the nervous system that receive, integrate, and transmit information.
nerve fiber
general term for any neuronal process that emerges from the cell body of a neuron
dendrite
a branch off the cell body of a neuron that receives new information from other neurons
axon
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
synaptic end bulb
Bulb at the end of an axon that Synapses or communicates with effector.
varicosities
varix or varicose condition in which a vein is swollen and tortuous
slow axonal transport
1-5 mm per day. from body to axon
fast axonal transport
200-400 mm per day, uses proteins that function as "motors" to move materials both directions--away from and toward the cell body-- along the surfaces of microtubules, moves various organelles and materials that form the membranes of the axolemma, synaptic end bulbs, and synaptic vesicles. materials tranported back tot he cell body are degreaded or recycled; others influence neuronal growth
synaptic vesicles
tiny oval-shaped sacs in a terminal of one neuron; assist in transferring mineral impulse from one neuron to another neuron by releasing specific neurotransmitters
multipolar neurons
have multiple dendrites and a single axon; most common type of neuron in CNS; all motor neurons that control skeletal muscles are this type
bipolar neurons
2 processes: axon and dendrite; rare; found in special sense organs: retina and olfactory mucosae
unipolar neurons
One process formed by fusion of axon and dendrite; Rapidly carries inputs over long distances (pain receptors of skin)
sensory(afferent) neurons
either contain sensory receptors @ distal ends(dendrites) or just after receptors that are seperate cells; sensory neuron forms action potential in axon & is conveyed to CNS thru spinal & cranial nerves.
Motor(efferent) neurons
A specialised neuron that carries messages away from the CNS towards the muscles, organs and glands. This enables bodily movements and activates internal organs and glandular secretions
Interneurons(association)
located within CNS between sensory and motor;integrate (process) incoming sensory info. from sensory, elicit motor response.
Neuroglia
cells within both the CNS and PNS, which, although they are external to neurons, form an essential part of nerve tissue
astrocytes
largest, most numerous glial cells; maintain blood-brain barrier to isolate CNS from general circulation; provide structural support for CNS; regulate ion and nutrient concentrations; perform repairs to stabilize tissue and prevent further injury
Oligodendrocytes
form myelin sheath around axons in the CNS, one can myelinate up to 50 axons
Microglia
Act as phagocytes, eating damaged cells and bacteria, act as the brains immune system
Ependymal
lines the cavities of the brain and spinal cord with cerebrospinal fluid. The cilia help t circulate the cerebrospinal fluid to protect the CNS.
Schwann cells
any cell that covers the nerve fibers in the peripheral nervous system and forms the myelin sheath
Satelite cells
regulate exchanges of materials between neuronal cell bodies & interstital fluid.
ganglion
an encapsulated neural structure consisting of a collection of cell bodies or neurons; in PNS.
white matter
whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths
gray matter
greyish nervous tissue containing cell bodies as well as fibers