12.2 Nervous Tissue Flashcards
Which structure propagates nerve impulses?
Axons
Which process receives information from synapses?
Dendrites
Flow of information in a Neuron
Dendrites > cell body > through axon
Axon Hillock
Initial segment
Where axon emerges from the cell body
Cytoplasm changes to axoplasm
Myelin
Protective coating over axons made from glial cells
Insulates axons
Node of Ranvier
gaps in myelin insulation
Axon Segment
segment wrapped by myelin on axon
Axon Terminal
end of the axon
Several branches extend to target
Synaptic End Bulb
end of the axon
Makes connection with the target cell at the synapse
Unipolar Neuron
One process extending from cell
Only found in invertebrates
In humans “pseudo-unipolar”
Splits so that the axon can extend a long distance
Dendrites at one end, axons connects with target at the other
Exclusively sensory neurons
Dendrites receive sensory info
Cell bodies are not always found in ganglia
Axon projects from dendrite endings to CNS
Bipolar Neuron
Two processes
Axon on one end, dendrite on the other
Uncommon cells
Olfactory epithelium and part of retina
Multipolar Neuron
One axon and 2+ dendrites
Majority of cells
Some are very small and conform as axon or dendrite depending on the function
Important to the cerebellum known as Purkinje Cells
Purkinje Cells
Multipolar neurons in the cerebellum
Types of Glial Cells
CNS
Astrocyte - Support
Oligodendrocyte - Myelination, Insulation
Microglia - Immune surveilance, phagotcytosis
Ependymal Cell - Creating CSF
Astrocyte
Support Star shaped many processes extending from main soma Interact with neurons, blood vessels or pia mater (CNS connective tissue) Maintain chemical concentration in extracellular space Removes excess signaling molecules Reacts to tissue damage Contributes to BBB
