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Non-Neuronal Cells of the Nervous System. Neuroglia Can’t generate or transmit nerve impulses (signals). Non-Neuronal Cells of the Nervous System. Central Nervous System (4 kinds of cells). 1) Astrocytes Provides neurons with nutrients & energy Physical support
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Non-Neuronal Cells of the Nervous System • Neuroglia • Can’t generate • or transmit nerve • impulses (signals)
Central Nervous System (4 kinds of cells) • 1) Astrocytes • Provides neurons with • nutrients & energy • Physical support • Forms the “Blood:Brain • Barrier”
2) Oligodendrocytes • Secretes myelin sheaths • around the axon of • the neurons (this • directs impulse)
3) Microglia • Are like Macrophages • Scavenge cell debris • Protects from • pathogens in the brain
4) Ependymal Cells • Line the hollow cavities • (ventricles) • Secretes cerebral & spinal • fluid which acts as • ‘shock absorber’, and distributes nutrients • in the brain and spinal cord
A myelin system • Protects cells Peripheral Nervous System
Transmission Of the Nerve Impulse
Before arrival of an Action (Electric) Potential Synapse (2 cells) Page 399
Action Potential opens channels that cause Calcium ions to move into the Synaptic Bulb
Neurotransmitters released into ‘cleft’ • Examples: • Glutamate (most common in brain) • Gamma-aminobutyric acid (GABA) • Dopamine • Acetylcholine • Epinephrine • Histamine • Serotonin • Neurotensin • Nitric Oxide • Neuropeptide Y
Neurotransmitters bind to receptors in next neuron...opening Sodium channels. This initiates an Action Potential in the next Neuron.
Neurotransmitters are cleared out of cleft. • By: • Diffusion • Reuptake by upper neuron • Enzymatic breakdown