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23 Cards in this Set
- Front
- Back
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Steps of neural signaling |
1.Stimulus 2.reception 3.transmission (by afferent neuron to CNS) 4.integration (by CNS interneurons) 5.transmission (by efferent neuron to effectors) 6.action by effectors |
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Neuron structure: Cell body |
-contains the nucleus and most of the organelles |
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Neuron structure: dendrites |
-branched structures that extend from cell body -receive stimuli and send signals to the cell body |
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Neuron structure: Axon |
-single long structure extends from cell body and forms branches called axon collaterals
-transmits signals into its terminal branches that end in synaptic terminals -release neurotransmitters |
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nerve |
-bundle of axons wrapped in connective tissue |
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ganglia |
-mass of neuron cell bodies (outside of CNS) |
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glial cells |
-support and nourish neurons -phagocytic cells -four types in vertebrates: astrocytes, oligodendrocytes, ependymal cells, microglia |
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astrocytes (type of glial cell) |
-support, nourish, phagocytic -regulate composition of extracellular fluid in CNS: remove excess K+ -blood-brain barrier |
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oligodendrocytes (type of glial cell) |
-form myelin sheaths around axons in the CNS |
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ependymal cells (type of glial cell) |
-ciliated glial cells -line internal cavities of the CNS -help produce and circulate cerebrospinal fluid |
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microglia (type of glial cell) |
-specialized macrophages near blood vessels
-respond to signal from neurons: important in mediating responses to injury or disease |
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neuron resting membrane potential |
-in a resting state, the inner surface of the plasma membrane is NEGATIVELY charged compared with the outside
- -70 millivolts across the membrane
-plasma membrane is electrically polarized |
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Factors determining resting potential |
-differences in concentration of Na+ and K+ inside the cell versus outside the cell -the membrane is more permeable to K+ than Na+ ions -ions pass through specific passive ion channels -negatively charged ions (Cl-) accumulate along inner surface |
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depolarized neuron membrane |
-stimulus causes membrane potential to become less negative (excitatory) -neuron is now capable of transmitting an impulse |
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hyperpolarized membrane |
-when membrane potential becomes more negative than the resting potential (inhibitory)
-neuron ability to transmit impulse is decreased |
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Action potential |
-depolarization of the membrane to a point where the stimulus is strong enough to transmit an impulse, because the voltage-activated ion channels open and Na+ can flow into the neuron which creates a less negative atmosphere inside the cell than at resting potential |
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repolarization |
-occurs after action potential -sodium pump gates close, so Na+ stops flowing in -K+ pump slowly opens and potassium flows out -returns to its more negative state |
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continuous conduction in impulse transmission |
-occurs in unmyelinated neurons -slower that saltatory jump because has to travel along whole axon |
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saltatory jump conduction in impulse transmission |
-myelinated neurons -more rapin than continuous conduction -depolarization skips along the axon from one node of ranvier to the next |
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presynaptic neuron |
-TERMINATES at a specific synapse |
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postsynaptic neuron |
-BEGINS at a specific synapse |
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the two types of synapses |
1.Electrical synapses -gap junctions: presynaptic and postsynaptic neurons are very close to each other. they are connected by protein channels that let ions pass from one cell to another
2.chemical synapses -pre and postsynaptic neurons are separated by a space (synaptic cleft) |
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The neurotransmitters |
1. acetylcholine (motor and muscle neurons) 2.biogenic amines (from amino acids) 3.amino acids 4.peptides 5.nitric oxide (NO) |
