Nervous Tissue Flashcards by sophie rosen

what is the structural and functional unit of the nervous system?

neuron

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what do neurons constitute? (3)

most sensory receptors
conducting pathways
integration centers

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where are most neuron cell bodies located?

CNS

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all neurons terminally differentiated (Go)…

do not divide, although regeneration of axons is possible

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what are the two basic cell types of nervous tissue?

neurons
supporting cells (non-conducting)

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what do supporting cells provide? (3)

physical support snd protection
electrical insulation
metabolic exchange

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3 categories of supporting cells

neuroglia in CNS
Schwann cells in PNS
stellate cells in ganglia

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soma contains

nucleus surrounded by cytoplasm

cell body

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perikaryon

area around the nucleus

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Kissel substance

rough ER

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neurilemma

plasma membrane surrounding the cell

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melanin, lipofuscin

age pigment within the cell body

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neuronal dendrites

one or more highly branched neuron processes

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dendrites receive stimuli from

other neurons or environment (afferent)

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single axon

transmits stimuli to other neurons or effector cells (efferent)

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axon arises from

Saxon hillock

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axon hillock terminates in the distal swelling called the

terminal bouton

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axonal transport

movement of products down the axon

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slow axonal transport carries

cytoskeletal elements

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fast exon transport carries

membrane bound organelles

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anterograde transport

from cell body down the axon

used kinesis

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retrograde transport

from axon to cell body

uses dynein

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multi-polar neuron

most common, several dendrites

ex. motor neurons, interneurons

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bipolar

single dendrite opposite axon

ex. receptor neurons of retina

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unipolar

no dendrites on soma, axon only | ex. sensory neurons

pseudo unipolar

insult dendrite and axon fuse, soma off to one side | ex. dorsal root ganglion

Na+ and Cl- are higher -- the cell

outside

K+ is higher -- the cell

inside

resting membrane potential inside the cell

~80 mV

action potential is an -- or none response

all

action potential arises in the cell body as a result of an

affect stimulus

causes region of the plasma membrane to

depolarize

causes reversal of resting potential, cells electrical potential

neutralized (goes to zero, or slightly positive)

during the refractory period,

na+ channels close and can't reopen for another 1-2 msec | Na+ is unresponsive to the stimuli

refractory period is initially ---, where response to stimulus is impossible, then ---, where only a very strong stimulus can initiate depolarization

absolute | initial

after Na channels close, voltage hated K channels also close, membrane depolarizes, ends

refractory period

opening and closing of na and k channels in a domino effect along the axon, the change in electrical potential of the membrane which travels down the axon as a

wave of depolarization

action potential is then conducted to effector cell at the synapse via

neurotransmitter

what are synapases/neuromuscular junctions?

specialized junctions between neurons or between neuron and effector cell (ex. mm)

each synapse is ---

unidirectional

response to stimulus max be either

excitatory or inhibitory

entrainment

more a pathway is used, easier it is to access

terminal bouton separated from the effector cell via the

synaptic cleft

what does the synaptic cleft contain?

mitochondria and membrane bound semantic vesicles containing neurotransmitters

signaling molecules are related from the

presynaptic membrane

diffuse across the synaptic cleft, bind to receptors on the

postsynaptic membrane

neurotransmitters used in the PNS

acetylcholine | norepinephrine (adrenaline)

sympathetic uses

noradrenaline (norepinephrine) as excitatory neurotransmitter (adrenergic)

parasympathetic uses

actyelcholine as the excitoru neurotransmitter (cholinergic)

vesicles on the post unapt membrane contain hydrolytic and oxidative enzymes such as (2)

acetylcholinesterase | MAO

inactive neurotransmitter between consecutive impulses prevents

continuous stimulation | ex. tetany

pns contains

afferent or efferent (axons) of either somatic or autonomic nn

cell bodies of PNS are located in

CNS or ganglia

peripheral nerve bundle

fascicle

Schwann cells derived from neural crest associated with axons provide

metabolic support and electrical insulation

nuclei along the length of the axon belong to

schawnn cells

in the PNS, all Nn enveloped by

Shawnee cells

Schwann cells provide

structural and metabolic support

in non myelinated Nn several axons lie in channels within Shawnee cells, surrounded by a single layer of

neurilemma from Schwann cells

myelinated Nn insulated by many concentric layers of plasma membrane from many

Schwann cells

the sachets of Schwann consists mostly of cell membrane and forms the

myelin sheath

many axons found together in a fascicle form a

nerve

nodes of ranvier

gaps in myelin sheath between adjacent Schwann cells

nodes of ranvier are responsible for

rapid, saltatory conduction

membrane depolarization only occurs as ---, not beneath Schwann cell, faster conserves electrolytes

nodes

myelinated Nn in the CNS sheathed by cells called

oligodendrocytes

one oligodendrocyte surrounded several NN with >1 layer of

plasma membrane

rate of conduction is proportional to the diameter of

the axon (bigger=faster) Myelin increases conduction rate

individual axons and Schwann cells are surrounded by loose connective tissue called the

endoneyrium

multiple axons are organized into bundles called fascicles surrounded by

perineurium

small diameter of Nn containing only one fascicle surrounded by

perineurium

cells of the perineurium are

unique, not just fibroblasts

;arger Nn containing several fascicles are surround by an additional layer of connective tissue called the

epineurium

blood vessels tend to follow

epi and peri neurium

cells of the perineurium exhibit --- and --- features. may play a role in axon regeneration

epitheliod and myoid

in the ANS, - neurons connect the CNS t viscera

2 | pre and post ganglionic neurons

preganglionic neurons have cell bodies in the

gray matter of the brain and cord in CNS

preganglionic axons synapse with

postganglionic

postganglionic cell bodies are found within

ganglia

discrete aggregations of postsynaptic neuron cell does located out the CNS

embryologically derived from the neural crest, like all

peripheral nn

each cell body (soma) is surrounded by

satellite cells

satellite cells are derived from

neural crest

satellite cells provide

structural and metabolic support

location of autonomic ganglia varies

sympathetic ganglia parallel to vertebral column | parasympathetic ganglia lie in or near the effector organ

sympathetic ganglia include -- and -- ganglia

prevertebral and paravertebral

prevertebral ganglia are located

anterior to the spine

paravertebral ganglia are located primarily in the

sympathetic trunk

parasympathetic ganglia are located

in or near the effector organ

Nervous Tissue Flashcards

(89 cards)