Nervous System Histology Flashcards
Direction of flow in information through the neuron
From dendrite to soma to axons to synapse
Current flows down axon to terminal boutons where it triggers?
Do all signals make it to the axon?
Secretion of a neurotransmitter
No, some impulses flow through dendrite and soma but do not make it to the axon (so never synapse)
All presynaptic terminals are both excitatory or inhibitory except ___ which is just ___
Axospinous is just excitatory
Function of a synapse
Presynaptic neuron has neurotransmitters stored in its terminal bouton. When signal is received, neurotransmitters are released into the synaptic cleft where it binds with a receptor protein in the cell membrane of a postsynaptic neuron
What do both pre and post synaptic membranes contain that bridge the synapse?
What is this necessary for?
Cell adhesion molecules (transmembrane proteins)
Synapse formation and activity induced structural plasticity
Location and function of the different morphologies of neurons:
- Pseudo-unipolar
- Motorneurons
- Local interneuron
- Neuroendocrine neuron
- Touch/pain receptors in skin/viscera and taste receptors. Typically located in a ganglion
- Anterior horn of spinal cord and brainstem (attach to muscle)
- Usually very short, unmyelinated axons in PNS and CNS
- Mostly in hypothalmus, release peptide hormones into blood (attach to capillary)
Axonal transport is done by what two proteins and in what direction
4 things that they transport
Are they fast or slow?
Kinesin = forward transport; dynein= transport back to cell body
Mitochondria, cytoskeletal proteins, enzymes, and vesicles
Slow
What kind of diseases result from problems with axonal transport?
Other potential clinical problem with axonal transport?
Neurodegenerative diseases
Viruses such as shingles/chickenpox and herpes can spread (dynein will transport back to cell body)
What cell types are similar in that they form myelin sheaths, but different because of location?
Difference in function?
Oligodendrocytes= CNS
Schwann cells = PNS
Oligos myelinate multiple axons, each schwann cell myelinates one axon (schwann also repairs axon)
Nodes of ranvier?
Gaps in myelin sheath that allows electrical signal to renew intensity
Axonal injury in PNS vs CNS?
When axon gets injured in PNS, what kind of cells enter to clean up debris? CNS?
Better regeneration in PNS (because oligos die, schwann do not)
PNS= macrophages CNS= monocytes that morph into microglia
4 clinical things that can cause demyelination of axons
Peripheral neuropathy, multiple sclerosis
Less common: vitamin b12 deficiency, trying to rehydrate someone too quickly
- Microglia: CNS or PNS? function?
- Astrocytes: CNS or PNS? Function?
- Ependymal cells: CNS or PNS? Function?
- CNS; release growth factors that promote homeostasis; attack invading pathogens
- CNS; Provide physical barriers protecting CNS, blood brain barrier, and regulate synaptic function
- CNS; form border between tissue and cavity containing CSF
Microglia dysfunction and disease can cause?
Auto immune disease (inappropriate immune cell migration across blood brain barrier)
Contributes to neurodegenerative disease(alzheimers) and contributes to damage following TBI
What kind of substances can diffuse through blood brain barrier?
Lipids or hydrophobic substances; hydrophilic must be actively transported
