S5 NS histology (incomplete. a lot of the photos for some reason were deleted. don't bother) Flashcards
describe a neuron
cell body/soma/ perikaryon nucleus: euchromatic with prominent nucleolus cytoplasmic extensions: dendrites and axons
clear portion of branch is the
axon hillock
swelling found at terminal branches
terminal boutons
types of synapses
axosomatic
axodendritic
axoaxonic: axon on axon where not myelonated
how to identify postsynaptic membrane on EM
It is always denser
Nissl stain/cresyl violet and luxol fast blue developed for
looking at cell body
stains basophillically- RER and polyribosomes
clumps of RER and polyribosomes are referred to as Nissl substances/bodies
Luxol fast Blue (LFB) give a good
dilineation of the tracts in the CNs
any demylation due to injury u will see as white areas.
pseudounipolar cells associated with
spinal (dorsal root) and granial ganglia and spinal and granial nerves
bipolar neurons associated with
some sense organs
vestibular-cochlear, retina, olfactory epithelium
How can you identify the axon from the dendrites on a nissl stain
Note that all the processes except one contain Nissl substance and are dendrites. The process that has no Nissl substance is the axon. The axon is not always the largest of the neuron’s processes.
types of neuroglia in CNs
types of neuro glia in PNS
types of astrocytes
protoplasmic astrocyte: Gray matter
Fibrous AStrocyte: white matter
specialized astrocyte: bergmann’s glial cell, muller cell, pituicyte
Glial fibrillary acidic protein:
specific for glial cells and astrocytes
Healing after injury in the brain occurs mainly by proliferation of
astrocytes. results in glial scar.
Glioblastomas
overproliferation of neuroglial cells. brain tumor. among most deadly or malignant forms of cancer.
components of blood brain barrier
tight junctions, endothelium, basement membrane, astrocytes
most abundant glial cell in white matter
oligodendrocytes
oligodendrocytes
have several processes, each of which produces a myelin sheath on a different axon that spirals in opposite directions.
how to id oligodendrocytes
cell bodies in rows in the white matter
microglia
belong to mononulcear phagocytic system; phagocytic function
smallest of glial cells, thorny bushes in appearance.
cells that produce CSF
Ependymal cells.
simple cuboidal/low columnar epithelial cells
ciliated
choroid plexus is made of
invagination of connective tissue pia matter, highly vascular, lined by epdyminal cells.
creates myelin sheath around most axons of PNS
Schwan cells or neurolemmocytes
outer surface of schwann cells
neurolemma
surround neuron cell bodies in the ganglia, provide support and nutrients
satellite cells
myelination occurs when
axon attains a diameter > 1um
schmidt-lanterman cleft
pockets of cytoplasm left when shwann cell was myleninating the axon.
where is this and what is this
myelianted axon. surruonded by schwann cell. outside of this is are collagen fibers, help indicate this is in the PNS
redish brown cells surrounding cell bodies
satellite cells
surround neuron cell bodies within ganglia
provide nutrients, remove metabolites etc.
pyramidal cells
Axon arises from the base and the dendrite from the apex.
The largest called BETZ cells.
layers of cerebral cortex
- molecular layer few cells, run horizontally
- Outer granule cell layer. Small cells
- Pyramidal cell layers.
- Inner granule cell layer. Small cells
- Inner pyramidal cell layer, large pryamidal cells
- Multiform layer: many different shapes.
layers of cerebellum
Molecular layer: few cells, glial cells
Purkinje layer: single layer only. Large cells.
Granule cell layer: packed neuronal cell layer
Nerve fibers: blue layer, axons of all the cell bodies.
Meissner’s corpuscle
light touch
Free nerve endings
nerve endings without special structural organization- pain and temperature receptor
Expanded tip endings:
- merkel’s touch corpuscle
- Type I hair cells of Vestibular Labyrinth
Pacinian Corpuscle (corpuscle of Vater-pacini
senses vibration
senses vibration
parcinian corpuscle (corpuscle of vater-pacini)
Genital corpuscle/ ruffini’s ending
respond to skin strech
responds to skin stretch
Genital Corpuscle- ruffini’s ending
End bulb of Krause- golgi tendon organ:
proprioceptor (sense the body’s position and movement in space)
identify this
pacinian corpuscles
have a central, unmyelinated neurite surrounded by layers of lamellae (composed of flattened Schwann/neurolemmocyte cells) that are separated by interstitial fluid and collagen fibres.
senses vibration
Gamma motor nerve fibers innervate the
intrafusal fibers
sensory fiber are located on modified, small (intrafusal muscle fibers)
Alpha Motor (large) nerve fibers innerve the
extrafusal fibers
injury to axons in CNS induces changes in the soma including
Chromatolysis (disruption) of Nissel bodies with a concomitant loss of cytoplasmic basophilia),
increase in soma volume
and movement of the nucleus to a peripheral position
Alzheimer’s disease and morpholigcal changes related to Nervous system disease
Tau are proteins that are responsible for stabilizing microtubules become defective and no longer stabilizes microtubules properly.
microtubule structures collapse and aggregates of abnormal proteins are formed “neurofibrillary tangles.”
Parkinson’s disease and morphological changes related to the Nervous system disease
•abnormal protein aggregates deposits within the neurons found in the substantia nigra nucleus (an important motor center which plays an important role in movement) forming Lewy bodies. (muscle rigidity, tremors, and changes in speech, etc..)
Multiple Sclerosis and Morphological changes related to the nervous system disease
Demyelination and destruction of oligodendrocyte.
chemical changes in the lipid and protein constituents of myelin produce irregular multifocal plaques in the white mater.
