Homework/Lab #8 Pictures – Flashcards
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Oligodendrocytes
These cells form myelin sheaths within the white matter of the CNS.
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Which of the neuroglial cell types shown form myelin sheaths within the CNS?
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dendrites
A indicates the dendrites of the neuron.
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What is the structure at A?
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multipolar
The neuron shown has many processes (axon and dendrites) that emerge from the cell body. Such neurons typically function as motor neurons or interneurons.
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What structural classification describes this neuron?
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both A and B
The dendrites and soma of the cell receive signals form other neurons.
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Which areas of this neuron would be classified as receptive regions?
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the voltage measured across the axon membrane at a specific point as an action potential travels past.
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What change in a neuron is being measured in the graph?
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Na+ ions move into the axon; K+ ions move out
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What best describes the direction followed by the specified ions when their voltage-gated channels open?
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chemically gated
The receptors at C are affected by the binding of a chemical neurotransmitter.
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How would the receptors at C best be classified?
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vesicles containing neurotransmitter
Neurotransmitters are released by secretion from the ends of axonal terminals.
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Which of these materials or structures would be found in the greatest amounts or numbers at E?
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C
Graded potentials originating in the dendrites and cell body are integrated (summated) at the axon hillock.
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In which area of the neuron is an action potential initially generated?
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C, D and E
Voltage-gated channels, which are triggered to open by depolarization of the membrane, are found ONLY in the axon, which in this image includes region D, but also includes the axon hillock (C) which is the initial segment of the axon, and region E, which is the terminal end of the axon - the axon terminal.
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Where would you expect to see voltage-gated channels?
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A and B
Chemically-gated channels are located primarily in the dendrites and cell body which are considered the "receptive" region of the neuron. This is where presynaptic axon terminals will form synapses on the neuron, and therefore are the parts of the neuron that will "receive" the incoming signals. The chemically gated channels are responsible for generating graded potentials, which are also known as synaptic potentials, and can be either EPSPs or IPSPs.
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Where would you expect to find chemically-gated channels?
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Na+ channels are inactivating, and K+ channels are opening.
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What is happening to voltage-gated channels at this point in the action potential?
