Neurons Flashcards
Ultrastructural characteristics of a neuron
abundant mitochondria, large centrally located euchromatic nucleus with prominent nucleolus, abundant RER (Nissl bodies)
What are the pigment granules of a neuron?
lipofusicin and melanin. lipofuscin may reflect wear and tear.
What are the dendritic sites of synaptic contacts?
dendritic spines
Where on the axon are APs generated?
initial segment
What kinds of axons have larger conduction velocities?
larger axons; myelinated axons
What ultrastructural characteristics are absent in axons?
no RER or ribosomes
What are two kinds of axon terminals?
at the end of the target: end boutons
if targets are adjacent to axons, the axon displays varicosities (aka boutons en passage)
What is anterograde transport? What mediates anterograde transport?
movement of things from the cell body out. can be fast or slow. slow is like diffusion; fast mediated by kinesins. ATP dependent.
What is retrograde transport? What mediates retrograde transport?
Dyneins mediate retrograde transport (related to cilia). moves things from the axon toward the cell body.
3 kinds of neurons
pseudounipolar, multipuola, bipolar
What is a pseudounipolar neuron? Where seen?
single process that bifurcates. example: sensory neurons as in DRG
What is a multipolar neuron? Where seen?
single axon and multiple dendrites. both sensory and motor; seen in brian, spinal cord, and peripheral autonomic nervous system
What is a bipolar neuron? Where seen?
2 processes that extend from opposite poles of the cell body. sensory. have been modified for olfaction, visual, vestibular, and auditory receptors
Describe interneurons
multipolar microneurons (golgi type II)
From where are macroglia derived?
neuroectoderm. can divide throughout life
