nervous system Flashcards
what is nervous tissue composed of
100 billion neurons and trillions of glial support cells
what does classification of nervous tissue depend on
differ in types of cells
describe nervous tissue classification anatomically
cns = brain, cerebellum, spinal cord = gray and white matter, can distinguish between
pns = nerve ganglia, nerve fibers
describe nervous tissue classification histologically
nerons - nerve cells
neuroglia - glial cells equivalent to the ct = involved in support, neuron protection, defense and nutrition
what is difference between CNS gray matter and white matter
gray = cell bodies of neurons, neuroglia
white = neuronal cell processes (axons), neuroglia
what is neuron
functional unit of nervous system
what does neuron consist of
dendrites
cell body
axons
describe dendrites
Receives signals
neurons synapse with each other and other things
describe cell body
integrates incoming signals from dendrites and outgoing signals to axons
soma, perikaryon
organelles and nucleus
describe axons
transmits signals to another neuron or effector cell
what is present in grey matter cns and ganglia pns
dendrites and cell bodies
what is present in white matter cns and nerve fiber pns
axon
what are the dots
nissl bodies
how to tell axon from dendrite
dendrites still have nissl bodies
axon hillock has no nissl bodies at begining of axon
do all nerons look the same
neurons have complex moprhology
perikaryons can be spherical, ovoid or angular
can have more than 2 processes = multipolar
not all neurons are typical and many have multiple polarities
name and describe types of neurons
pyramidal - brain cortex
purkinje - cerebellum
motor neurons - spinal cord
pseudounipolar - spinal ganglia, bifurcates- opens in 2, arborizes, branches
bipolar = retinal, olfactory, mucosa, originates from same cell body then goes in 2 opposite directions
name parts of cns
cerebrum
cerebellum
spinal cord
what does cns show when sectionned
regions of white or grey matter when sectioned
what does gray matter have
neuronal cell bodies and neuroglial cells
what does white matter have
axons and neuroglial cells
appears white due to presence of myeline around myelinated axons
where is cerebrum
upper portion of brain
what is function of cerebrum
integration of sensory information (from peripheral nervous system= sensory modalities = olfactory,touch, language,learning,nearing
initiation of voluntary motor Responses - motor cortex
describe histology of cerebrum
white matter appears lighter
gray matter appears darker, more homogenous
describe white matter of cerebrum
both longitudinal and cross section
broken up appearance
where myelin used to be - white spaces, does not preserve well
describe gray matter of cerebrum generally
can trace where axons are
entirely different
no myeline since no axons
cell bodies and nucleus
smaller = neuroglial cells in white and gray mater = support cells, maintains, supports and protects tissue