chapter 12 nervous tissue

25 terms by jessie-allen

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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

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