Lec 2 Review of brain histology Flashcards
Where in the neuron does the action potential initiate?
the spike initiaion zone in the nerve cell body (soma) near the axon hillock
What are boutons?
swellings at the ends of axon terminal
What is a telodendron?
the entire array of terminals for one axonal process
What are neruonal processes?
non-specifically refer to axons and dendrites
What is structure of multipolar neurons?
- 3-5 primary dendrites coming off cell body
- axon emerges from axon hillock
Where do you find multipolar neurons?
through the CNS
What is structure of bipolar neurons?
- single process
- cell body located directly along the course
- distal extension is dendrite, proximal (directed toward CNS) is axon
Where do you find bipolar neruons?
- retina
- in clusers of cell bodies (ganglia) of vestibular and auditory cranial nerves
What is structure of unipolar neurons?
- single process extends proximally and distally from a short segment that connect it to the cell body
- both parts of process technically called neurites (or distal = dendrite, proximal = axon)
Where do you find unipolar neurons?
sensory ganglia in PNS
notably in dorsal root ganglia
What is structure of pyramidal cells?
- pear shaped soma, several dendrites
large, highly branched dendrite from apex of soma called apical dendrite
- axon from base of the cell body
- have dendritic spines
What is function of dendritic spines?
What are granule cells? structure?
- smaller, star shaped (stellate)
- dendritic tree radiates out in all directiosn from the soma
- provide much of local (regional) info processing)
What are the 3 different types of neurons as classified by length of axon?
- projection clels
- interneurons
- amacrine cells
What are projection cells?
- neurons with long axons
- axons extend long distance, send neural signal from one region of nervous system to another
- long axons sometimes branch into: 1. main axon that projects to chief target site, 2. axon collateral that projects to another far location
What are interneurons?
- neurons with short axons
their axons remian within the region of cell’s dendritic field
- provide local synaptic interactions and feedback
- many are inhibitory
What are amacrine cells? Where are they found?
- axon-less neurons
- found in retina and olfactory bulb
What is the neuromuscular junction?
- specialized version of a synapse
- motor neuron + NMJ forms motor end plate consisting of enlarged axon terminal with synaptic vesicles, junctional folds, enlarged synaptic clefs, muscle sole plate
What are the 3 general neruonal cell death pathways?
- necrosis
- apoptosis
- autophagy
What factors lead to selective vulnerability?
- cytoarchitecture
- physiology/metabolism
- regional/network associations
- blood supply
In what diseases is prolonged microglia activation thought to play a role in neurodegeneration?
- alzheimers
- parkinsons
- viral (HIV, HSV) infections
- bacterial (streptococcus pneumoniae) infections
- parasitic (plasmodium falciparum) infections
What are two types of lower motor neuron diseases?
ALS, polio
What are two subtypes of astrocytes?
fibrous (found in white matter)
protoplasmic (found in gray matter)
Why do myelinated axons appear white?
myelin has high lipid content
What makes of gray vs white matter?
white matter contains myelinated fiber tracts
gray matter contains high concentrations of cell bodies
What type of disease is multiple sclerosis?
A demyelinating disease
What is schwannoma?
a benign encapsulated tumor originating from schwann cells
