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21 Cards in this Set
- Front
- Back
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CNS |
Brain (cerebrum, cerebellum, subcortical structures, and brainstem) and spinal cord |
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PNS |
cranial and spinal nerves |
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Astrocytes |
help separate neurons from each other, important for supplying nutrients, help create the blood brain barrier, kept toxins from blood from affecting the brain |
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Microglial Cells |
eat up necrotic tissue fromed by injury or lesion |
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glial cells |
supporting synaptic activity in neural system outnumber neurons 10-1 |
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–Oligodendrocytes
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-make up myelin in CNS
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Schwann Cells |
make up myelin in PNS |
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Neural Transmission |
•chemicalsubstance released from preceding neuron reacts with the cell membrane•generatesa postsynaptic electrical potential•Canbe excitatory or inhibitory
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Resting State of Neuron (Inside) |
-unequal concentration on either side of axon wall -high concentration of K+(30 times as much inside than out) -inside low concentration of Cl- and Na+ |
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Resting state of neuron (outside of wall) |
-high Na+ concentration (10x) -about -70mV |
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Resting Potential |
the amount of negative charge inside cell body |
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sodium potassium pump |
pumpNa+ back out and K+ back in maintains resting potential runs on ATP from mitochondria concentration gradient maintained |
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passive movement of ions |
membrane is semi-permeable concentration gradient is maintained by pump inside of cell negative relative to outside |
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excitatory |
depolarization of dendritic zone |
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inhibitory |
hyperpolarization of neuron, (raises the threshold for firing) |
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Critical firing level for transmission |
-50 mV |
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Actionpotential
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-occurs when cell membrane is adequately stimulated (reaches a threshold)
-allows ion exchange between intracellular and extracellular spaces -Na+ allowed into cell, changes the charge inside the cell to positive, known as depolarization |
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Absolute Refractory Period |
–Furtherstimulation of neuron in that area of membrane has no effect for about 1 msec.
-Cannot fire until RMP reaches -50 mV |
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Relative Refractory Period |
–Followsthe absolute refractory period
–Occurswhen RMP reaches -50mV again –Lasts3 to 4 msec in motor nerves –Membranerequires greater than normal stimulation to fire again |
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Spatialsummation
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—impulses from many different activations from different parts of the dendrite arrive at the same time
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Temporal summation
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if many small epsp arrive at in quick succession from the same , the neuron ismore likely to fire
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