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40 Cards in this Set
- Front
- Back
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dendrites |
appendages from soma (nucleus) receive signals, which are transmitted to axon hillock, which integrates |
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axon |
long appendage of neuron that terminates near target structure |
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myelin |
in mammalian nerve cells, insulates to prevent signal crossing or loss increases speed produced by oligodendrocytes in CNS and Schwann cells in PNS Small breaks called nodes of Ranvier |
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nerve terminal |
aka synaptic bouton at end of axon enlarged and flattened to maximize neurotransmission |
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synaptic cleft |
space into which neurotransmitters released- they bind to dendrites at post-synaptic neuron |
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synapse |
nerve terminal + synaptic cleft + post-synaptic membrane |
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nerves |
bundle of neurons in the PNS, can include sensory, motor, or mixed |
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ganglia |
cluster of cell bodies of neurons of the same type |
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tracts |
bundles of axons in the CNS- only carry one type of info |
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astrocytes |
type of glial cell nourish neurons and form blood/brain barrier |
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ependymal cells |
line brain ventricles, produce cerebrospinal fluid |
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microglia |
phagocytic, break down waste and pathogens in CNS |
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resting potential |
electrical potential difference between inside neuron and extra cellular space usually around -70 mV (inside neg to outside) |
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Na+/K+ ATPase |
maintains resting potential (negative inside cell) by moving 3Na+ ions out for every 2 K+ ions in ATP necessary bc moved against gradient |
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depolarization |
caused by excitatory input membrane potential increased from resting potential more likely to fire action potential |
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hyperpolarization |
caused by inhibitory input membrane potential decreased from resting potential less likely to fire |
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action potential |
triggered if axon hillock receives enough to be depolarized to threshold (-55 to -40 mV) |
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action potential mechanism |
when cell is brought to threshold, voltage-gated sodium ion channels open. sodium passes into cell, rapidly depolarizing it. when membrane potential (Vm) reaches +35 mV, sodium channels are inactivated and have to be brought back to near resting potential to be deinactivated |
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repolarization |
potassium flows out of cell (happens after sodium depolarizes bc electrochemically favorable now) this causes overshoot of resting potential (hyperpolarization) making neuron refractory to more action potentials (refractory period can by absolute or relative) |
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impulse propagation |
sodium rushing into one segment causes depolarization of surround regions, continues to move down axon toward nerve terminal only in one direction bc prior segment momentarily refractory after firing |
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speed of impulse propagation |
depends on length and cross-sectional area of axon greater cross-section- faster bc less resistance length is less significant, but longer is slower |
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increased intensity of stimulus |
leads to increased frequency of firing, not increased potential difference |
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release of neurotransmitters |
stored in membrane-bound vessels in nerve terminals voltage-gated calcium channels open when action potential reaches terminal and calcium flows into cell, causing exocytosis of neurotransmitters |
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neurotransmitter received at post-synaptic neuron/effector |
receptors usually either ligand-gated ion channel or G-protein coupled receptors. If ligand-gated, post-synaptic cell either depolarized or hyperpolarized if G-protein, cause change in levels of cAMP or calcium influx |
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3 methods to remove neurotransmitter from synaptic cleft |
1. broken down by enzymatic reactions 2. brought back to presynaptic neuron by reuptake carriers 3. can diffuse out |
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white matter |
in CNS. axons in myelin sheaths (usually lie deeper) |
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grey matter |
in CNS unmyelinated cell bodies and dendrites |
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dorsal root ganglion |
in spinal cord, contains cell bodies of sensory (afferent) neurons |
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afferent |
towards |
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efferent |
away |
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parasympathetic nervous system response |
-ACh responsible for parasympathetic, released by both preganglionic and postganglionic neurons -vagus nerve responsible for innervation of thoracic and abdominal cavity- digestion |
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sympathetic nervous system response |
preganglionic releases ACh, postganglionic releases norepinephrine |
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reflex path |
pain receptor to sensory neuron to interneurons, then to muscles quickly and brain more slowly |
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dopamine |
neurotransmitter in CNS activates reward circuit |
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serotonin |
neurotransmitter in CNS mood, sleeping, eating, dreaming |
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GABA |
neurotransmitter in CNS brain "stabilizer"- inhibitory function, keeps neurons from firing out of control |
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endorphins |
in CNS painkillers, have slower and longer effects |
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epinephrine |
neurotransmitter in PNS "fight or flight" |
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norepinephrine |
neurotransmitter in PNS regulates wakefulness and alertness |
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acetylcholine |
in PNS, regulates voluntary muscle control in CNS, regulates attention and arousal |
