Biology 1361: Neurons, Synapses and Signaling
42 Cards in this Set
Front | Back |
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Neuron
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Nerve cells that transfer information within the body
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What two kinds of signals do neurons transfer?
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Electrical (long-distance)
Chemical (short-distance)
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Where does the processing of information take place?
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ganglia
brain
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Ganglia
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Simple clusters of neurons
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Brain
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More complex cluster of neurons
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What are the 3 stages of processing information?
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Sensory input
Integration
Motor output
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Sensory Neurons
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Detect external stimuli (light, sound, touch, heat, smell, and taste) and internal conditions (blood pressure, muscle tension, and blood carbon dioxide levels)
Part of sensory input stage.
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Interneuron
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- Integrate information sent to the brain or ganglia
- Part of integration stage
- Most neurons in the brain are interneurons
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Motor Neuron
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Motor output leaves from the brain or ganglia; triggers muscle or gland activity.
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What are nervous systems consisted of? (2 things)
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Central nervous system (CNS)
Peripheral nervous system (PNS)
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Central Nervous System (CNS)
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Where integration takes place
Includes brain and spinal cord
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Peripheral Nervous System (PNS)
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brings information in and out central nervous system (CNS)
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What is the structure of a neuron?
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cell body
dendrites
axon
axon hillock
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Cell body
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Where most of a neuron's organelles (including nucleus) are
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Dendrites
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Highly branched extensions that RECEIVES signals from other neurons
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Axon
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Longer extension that TRANSMITS signals to other cells at synapses.
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Axon Hillock
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connection between axon and cell body
signals that travel down the axon are generated here.
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Synapse
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junction between an axon and cell body
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Synaptic Terminal
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passes information across the synapse in the form of chemical messengers called neurotransmitters.
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Neurotransmitters
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pass information from the transmitting neuron to the receiving cell.
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Presynaptic Cell
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A neuron
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Postsynaptic Cell
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A neuron, muscle, or gland
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Glia
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supporting cells
nourishes or insulates most neurons
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membrane potential
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charge difference, or voltage, across the plasma membrane
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resting potential
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a resting neuron that isn't sending a signal.
typically between -60 and -80 mV (millivolts)
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is K high inside or outside cell?
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inside
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is Na high inside or outside the cell?
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outside
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is anions high inside or outside the cell?
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outside
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gated ion channels
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open and close in response to stimuli
the opening and closing of these channels change the membrane potential
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When gated K+ channels open, K+ diffuses out, making the inside of the cell more negative. What is this an example of?
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hyperpolarization
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What is hyperpolarization (-)?
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the increase in the magnitude of the membrane potential
makes the inside of the membrane more negative (-)
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what is depolarization (+)?
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the reduction in the magnitude of the membrane potential
makes the inside of the membrane LESS negative
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Na+ channels open and Na+ diffuses into the cell. What is this an example of?
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depolarization
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What are the 5 major classes of neurotransmitters?
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acetylcholine
biogenic amines
amino acids
neuropeptides
gases
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electrical synapses
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the electrical current flows from one neuron to another
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chemical synapses
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chemical neurotransmitter carries information across the gap junction
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Most synapses are chemical or electrical?
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chemical
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when most voltage-gated Na+ and K+ channels are close, but some K+ channels (not voltage-gated) are open. is that action potential or resting potential?
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resting potential
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When an action potential is generated
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voltaged-gated Na+ channels open first and Na+ flows into the cell.
rising phase.
falling phase.
undershoot
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What happens during the rising phase?
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the threshold is crossed and the membrane potential increases
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what happens during the falling phase?
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the voltage-gated Na+ channel is inactivated
voltage-gated K+ channels open and K+ flows out of the cell.
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what happens during the undershoot phase?
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membrane permeability to K+ is higher than at rest, then voltage-gated K+ channels close, resting potential is restored
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