-
nerve tissue
-from ectoderm
- neurons = cells
- nerves = multiple processes of cells
-
components of neuron
soma, dendrite, axon,
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SOMA
- -cell body
- -large nucleus
- -nissl substance (RER)
-
dendrite
surface area for incoming signals
-
axon
- -conducts signals away
- -axolemma
- -axoplasm
- -microtubules
- -microfilaments
-
•Schwann cells form myelin (in PNS)
•Multiple cells, separated by nodes
•(nodes of Ranvier)
•Myelin provides insulation
•Nodes speed conduction of impulse
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Support cells of CNS: astrocytes
- -blood-brain barrier
- -homeostasis of neuronal environment
-
Support cells of CNS: Oligodendrocytes
- -myelin
- •many axons per oligo.
-
support cells of CNS: Microglia
macrophage
•CT, not neural origin
-
Glial cells in CNS
- satellite cells: protect SOMA of ganglion (cell body)
- schwann cells: protect axons
-
-
synapses
- function: polarization of impulses passing from one neuron to the next
- strategy: chemical --> electrical --> chemical
-
components of a synapse
- presynaptic neuron:
- -neurotransmitters (acetylcoline, norepinephrine, dopamine, seratonin, ect)
- postsynaptic neuron:
- -specific receptors coded for neurotransmitters
- synaptic cleft:
- -inactivation enymes
-
convergence vs divergence
convergence: many inputs converge into one output
divergence: one input diverges into many outputs
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