NS 2 - Histology Flashcards
What is Axoaxonic type of neuron?
excitatory or inhibitory, increase or decrease neurotransmitter release by postsynaptic terminal
what is axospinous type of neuron?
excitatory synapses
What is axodendritic type of neuron?
excitatory or inhibitory synapses
What is axosomatic type of neuron?
excitatory or inhibitpry synapses
What is an axonal varicosity?
Bead like terminal on axon that releases neurotransmitter
Sensory/Pseudo-unipolar neuron
touch, pain, taste (ganglion)
motor neuron
spinal cord (anterior horn), brain stem (cranial nerve motor nucleus)
local interneuron
very short, unmyleinated axons of CNS/PNS
Neuroendocrine
hypothalamus, releases peptide hormones (systemic or portal) typically to capillary
Kinesin function of axonal transport
anterograde, to positive terminal or positive dendrite end
Dynein function of axonal transport
retrograde, toward soma, negative end
Clinical significance of axonal transport
viruses spread in peripheral neuropathies, some viruses such as rabies can jump across synapses
Schwann cells and ogliodendrocyte for conduction of AP
myelin sheath has gaps which are nodes of ranviers where sodium channels are for allowing AP
What is the mechanism of action for demyleination diseases/disorders?
ineffective proteins between the multiple lipid bilayers, degradation of Myelin Basic Protein and Peripheral Myelin Protein 22 are key targets
Axonal injury
NOT demylienation but actual injury. Can regrow but can’t take itself to CNS/PNS
Anterograde is distal to injury
Schwann cells are scaffolding and protection for regeneration
Schwann cells in PNS with axonal injury
macrophages clean up yucky injury area but schwann cells are what create favorable environment for re-growth
Much better regrowth
Ogliodendrocytes in CNS with axonal injury
monocytes turn to microglia to clean up debris but still problems
Oglios like to die off as easily damaged and create scar tissue
peripheral neuropathy
demyelination axons in peripheral
slows electrical conduction/sensory process/muscle weakness
speed of conduction key to show demyelin not axonal (signal amplitude)
causes of peripheral neuropathy
autoimmune, typically causes change in action potential and connection with peripheral nerves
MS
attack against myelin sheath CNS azons, creates 2+ focal lesions
B12 deficincy
can develop due to alcohol abuse causing problem with PNS nerves on CNS axons
Glial Cells
ogliodendrocytes (CNS), schwann cells (PNS), microglia, astrocytes, ependymal cells
Microglia
immune surveillance CNS, attack invading pathogens
astrocytes
play role in BBB by keeping normal extracellular environment or supplying molecules to neurons regulate synaptic function
ependymal cells
form single layer along deepest border between tissue and CSF cavity
Microglia in microscopy
small, flat bodies in resting state
some traumatic event causes them to synthesisze material and release info which creates expanded size in active state
auto immune disease microglia
something triggers inappropriate inflammation where prevent self recognition and react to CNS antigen as foreign
Astrocytes
multiple function with many dendrites, they gather together at site of inflammation or injury to create impenetrable barrier to prevent spread
Astrocytes 3 main location
barrier just inside pia layer
BBB & surrounding capillaries
envelope part of neuron to control extracellular environment for normal neuron
Astrocyte 3 parts in barrier making
astrocyte barriers have non-fenestrated tight junctions, mean completely impenetrable
pericytes are involved by moving substance across membranes
astrocytes extend feet around pericyte
astrocyte and BBB
lipid/hydrophobic diffuse spontaneous across BBB (steroid & hormones)
water soluble can’t diffuse BBB, need active transport (glucose, amino acids, nucleotides)
medications sometimes need alterations to be able to use active transport
white matter contents
myelinated axons
gray matter contents
cell bodies & dendrites, few or none axons
Anterior/ventral roots carry what axons?
motorneurons project to skeletal
dorsal/posterior roots carry what axons?
sensory neurons that have cell bodies in dorsal/posterior ganglion
what do peripheral nerves carry?
axons of sensory, motor, and autonomic neuronsas
sensory ganglions pathway
sensation: skin, conective tissue, bone, joint, muscle, tendon, visceral organ
Synapse: in spinal cord, brain stem
Doesn’t have synaptic connection, bypass go one end to next
Sympathetic chain
from T1-L2 of spinal cord, then synapse paravertebral and project on to further target
parasympathetic ganglion
from brainstem or S2-S4 spinal cord then synapse on parasympathetic ganglion near target, project onto nearby target
