SDL: Neurocytology and CSF Flashcards
the trophic (metabolic) center of the neuron
the neuronal soma, defined by presence of the nucleus
the longer the axon,
the wider the soma’s diameter
three basic shapes of neurons
pseudounipolar, bipolar, multipolar
characteristic of pseudounipolar neuron
a single process which extends from the soma then bifurcates
characteristic of a bipolar neuron
bipolar neurons have 2 processes, 1 an axon, the other a dendrite
characteristic of a multipolar neuron
1 axon and 2 or more dendrites extending from the soma
what portion of the nervous system are pseudounipolar neurons found in?
peripheral sensory system
the most rare neuronal shape, and where are they found?
bipolar neurons, in the peripheral nervous system
most common type of neuron
multipolar
characteristics of the cell membrane of neurons
cover axon, soma, dendrites; contains receptors (glycoproteins, glycolipids); contains ion channels
name given for rough ER that is large, organized into parallel cisternae with numerous polyribosomes between them
Nissl substance or Nissl bodies
where are Nissl bodies found in the neuron, and what do they produce?
found everywhere except the axon; make structural proteins and NT peptides
where are neuronal mitochondria often found?
in the presynaptic terminals
what is the function of microtubules in neurons?
movement of substances and organelles within the cytoplasm; can move in both directions
transport away from the soma is called
anterograde transport
transport toward the soma is called
retrograde transport
where are microtubules more abundant: axons or dendrites?
dendrites
what is a lipofuscin granule?
an inclusion of a neuron that contains substances that were not digested by the lysosome; the older the neuron, the more lipofuscin granules it has
byproduct of catecholamine synthesis that is another inclusion found in neurons
melanin
what is the level of myelination of peripheral DRG (dendrites)?
unmyelinated or lightly myelinated (like pain and temp. receptors)
increased degree of myelination means..
faster rate of conductance of impulses
the axon hillock can be distinguished from other processes by..
the lack of Nissl bodies
unlike the dendritic tree, the axon of a neuron can
leave the CNS and enter the PNS
type of neuron that is important for development and maintenance of the blood brain barrier
astrocyte
type of neuron derived from mesoderm (rather than ectoderm); what it functions as
microglia that migrate in and out of the CNS; participates in the inflammatory response and phagocytic processes
neurons that line the inner CNS
ependyma cells
ependymal cells can participate in passage of substances between
the CNS and CSF
cells that form a CSF-blood barrier
choroid epithelial cells (differentiated ependymal cells)
makes up the H-shape in the spinal cord
gray matter
areas of gray matter which contain intermingled processes like axons and dendrites
neuropil
a type of neuronal organization in which the somata are arranged in layers
laminar
found deep to the cortex of the brainstem and cerebellum, and surrounds the H shape of the spinal cord cross section
white matter
the presynaptic side of the synapse that has the small bulb of the end of the axon is called the
bouton
is the synaptic cleft an empty space?
no, it has fine filaments and polysaccharides that bind to the 2 membranes tightly
which receptor plays a large role in strengthening of synapses, and what is the mechanism?
NMDA receptor; F actin filaments change the conformation of the post synaptic site, which makes it more capable of processing signals and placing them into “memory”
example of a large complex of intracellular proteins called “signaling machines”
CaM Kinase II
in what type of junction does an electrical synapse occur?
gap junction, a passage for ions and small molecules
the terminal of a synapse on a skeletal muscle is called
motor end plate
neuronal-glandular cell terminations
secretomotor synapses
axons from neurons such as those in the hypothalamus which pass to the hypophysis
neurosecretory axons
describe astrocytic-oligodendritic interaction
astrocytes appear to “prime” axons for myelination
describe astrocytic-microglial interactions
produce cytokines, growth factors; play major role in communication between CNS and the remainder of the body (since the CNS lacks lymphatics)
an ultrafiltrate of plasma consisting of proteins and electrolytes; circulates through ventricular system and subarachnoid space, reabsorbed by arachnoid granulations
CSF
main site that produces CSF
choroid plexus
what does the BBB exclude?
macromolecules (proteins), limits small non-lipid soluble molecules
Congenital or acquired stenosis of the cerebral aqueduct prevents normal CSF egress and results in dilated lateral and third ventricles and a small fourth ventricle, causing what type of hydrocephalus?
non-communicating or obstructive hydrocephalus
causes of non-communicating hydrocephalus
tumor, infection, inter-ventricular bleeding
when arachnoid granulation function is compromised due to increased venous back pressure or abnormally low CSF pressure
communicating hydrocephalus
CSF can leave the brain, but not the cranial cavity
communicating hydrocephalus
CSF can’t leave the brain via the cerebral aqueduct
non-communicating hydrocephalus
how hydrocephalus (both kinds) are treated
shunts to other body cavities
