Lecture 9: Histology of the Nervous System Flashcards
Ventricular Space
Internal core of CNS, sac filled with CSF, flows into subarachnoid space, lined by ciliated ependymal cells
Polarization of Neurons
structurally polarized by axon vs. dendrites; microtubules positive ends towards terminal bouton of axon, negative end towards nucleus
Bipolar Neurons
Found in the retina and all cells related to the 8th cranial nerve (auditory)
Multipolar neurons
found everywhere
unipolar neurons
Found in DRG
2 main types of neuron shapes
pyramidal (all have spines) and spiny stellate
dendrite spines effected by
experience, learning, memory, cognition, plasticity, hormones and aging
amacrine cells
no axon, famously found in retina
telodendrons
branching of axons, end in terminal boutons
Parts of synapse
presynaptic membrane (of axon, can see vesicles); synaptic cleft; post-synaptic membrane density
the neuro-muscular junction
presynaptic membrane very inter-folded with-in the muscle tissue, called junctional folds
Enlarged terminal bouton called end-plate
enlarged synaptic cleft
Synapsing muscle called sole-plate
Differences serve to increase the amount of neuro-transmitter released
motor neuron
V. prominent nucleolus, lots of nissl bodies (RER site, needs to make protein for neurotransmitters)
Affected by polio and ALS
three types of neuronal cell death
apoptosis (natural/abnormal), necrosis/cytoplasmic (brain trauma), autophagy (auto-immune disease
Glia types
astrocytes, oligodendrocytes, microglia
Microglia
CNS macrophages, activated by inflammation, can be helpful and harmful
Astrocytes
Scavenge neurotransmitters that is leaking, funnel back into neuron; form a lining around the capillary with feet-like processes. All blood vessels in brain covered by astrocyte perivascular end-feet, one astrocyte will cover multiple capillaries
oligodendrocytes
Processes of one form myelin sheath for many axons, gaps in myelin sheath create nodes of ranvier, saltatory conduction
multiple sclerosis
demyelinating disease of CNS
PNS myelination
Supplied by Schwann cells (neurolemmocytes)
Schwann cells function
cover all PNS axons, if axon is myelinated will wrap around axon many times creating insulating myelin sheath, nodes of ranvier not insulated but still covered by cell processes
neurolemmocytes
another name for schwann cells
PNS connective tissue layers
PNS cell –> Schwann cell –> Endoneurium (CT) –> many neurons make up one fasicle/fasiculus –>perineural epithelium –> perineurium (fibrous CT)–> many fasicles make up nerve trunk –> epineurium
