Principles of Biology
2nd Edition
ISBN: 9781259875120
Author: Robert Brooker, Eric P. Widmaier Dr., Linda Graham Dr. Ph.D., Peter Stiling Dr. Ph.D.
Publisher: McGraw-Hill Education
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Chapter 33.4, Problem 2TYK
Summary Introduction
Introduction:
Neurons form an important aspect of the nervous system. They are responsible for the transmission of a signal between different body parts. The signal is transmitted either through electrical impulses or chemical impulses. The chemical stimulus is transmitted through some molecules known as neurotransmitters.
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Which of the following are the likely explanations for the failure of a postsynaptic neuron to trigger an action potential? Select all that apply.
The EPSPs are neutralized by the neurotransmitter
The summation of IPSPs and EPSPs is insufficient to depolarize the cell to threshold
The synapses generating the EPSPs are too close to the axon hillock
The synapses generating the EPSPs are too far from the axon hillock
When a neurotransmitter binds with receptors at the membrane, it may cause sodium channels to open. An inflow of sodium causes the membrane to partially depolarize and become less negatively charged. For example, the voltage might change from -70 mV to -65 mV. This partial depolarization of the dendrites and cell body acts as:
an EPSP, exciting the cell and increasing the likelihood of action potentials.
an IPSP, inhibiting the cell and reducing the likelihood of action potentials.
none of these options; depolarization has no excitatory or inhibitory effect on a neuron.
both an EPSP and and IPSP.
Acetylcholine is a neurotransmitter that, when bound to its receptor, causes the receptor to open a
channel that allows the flow of Na+ ions into neurons.
When the Na+ ions begin to flow into the neuron, this change in the net charge across the neuronal
cell membrane often triggers Ca2+ ion channels to open.
In this scenario, the acetylcholine receptor would be acting as a
channel, and the Ca2+ channels would be classified as
voltage-gated; leaky
ligand gated; voltage-gated
symporter; antiporter
None of the above.
ion
Chapter 33 Solutions
Principles of Biology
Ch. 33.1 - Which of the following is false? The CNS of...Ch. 33.1 - Prob. 2TYKCh. 33.1 - Prob. 1CCCh. 33.2 - Prob. 1CCCh. 33.2 - Prob. 1BCCh. 33.2 - Prob. 1TYKCh. 33.2 - The resting membrane potential occurs because the...Ch. 33.3 - Are ions the only substances that can move through...Ch. 33.3 - Prob. 1CCCh. 33.3 - Prob. 2CC
Ch. 33.3 - Which is false? Graded potentials may die out or...Ch. 33.3 - Action potentials require a threshold potential...Ch. 33.4 - Prob. 1CCCh. 33.4 - Prob. 1TYKCh. 33.4 - Prob. 2TYKCh. 33.5 - Prob. 1BCCh. 33.5 - Prob. 1TYKCh. 33.5 - Prob. 2TYKCh. 33.6 - Prob. 1CCCh. 33.6 - Prob. 2CCCh. 33.6 - Prob. 3CCCh. 33.6 - Prob. 1TYKCh. 33.6 - Prob. 2TYKCh. 33.7 - Prob. 1TYKCh. 33.7 - Therapeutic drugs that reduce symptoms of...Ch. 33 - Prob. 1TYCh. 33 - Prob. 2TYCh. 33 - Prob. 3TYCh. 33 - Neurons that function mainly in connecting other...Ch. 33 - Prob. 5TYCh. 33 - Prob. 6TYCh. 33 - Prob. 7TYCh. 33 - Prob. 8TYCh. 33 - Prob. 9TYCh. 33 - Prob. 10TYCh. 33 - Describe the differences between graded and action...Ch. 33 - Prob. 2CCQCh. 33 - Prob. 3CCQCh. 33 - Prob. 1CBQCh. 33 - Prob. 2CBQ
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- Assume presynaptic excitatory neuron A terminates on a postsynaptic cell near the axon hillock and presynaptic excitatory neuron B terminates on the same postsynaptic cell on a dendrite located on the side of the cell body opposite the axon hillock. Explain why rapid firing of presynaptic neuron A could bring the postsynaptic neuron to threshold through temporal summation, thus initiating an action potential, whereas firing of presynaptic neuron B at the same frequency and the same magnitude of EPSPs may not bring the postsynaptic neuron to threshold.arrow_forwardSome postsynaptic synapses are called silent synapses due to the lack of AMPA receptors. Why do those synapses not have a synaptic response at the resting membrane potential? Explain under what conditions you would still be able to detect a postsynaptic response from those silent synapses.arrow_forwardIn an experiment, the extracellular [Na+] surrounding a nerve cell was reduced from 145 to 45 mM. Which of the following is the most likely effect of this on action potentials? No action potentials would occur because the concentration of extracellular Na+ is too low. The membrane potential would become more negative so the threshold for action potential generation could not be reached. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarisation phase would be slower. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarization phase would be more rapid.arrow_forward
- Consider the following three diagrams of a nerve cell membrane. They show resting potential, depolarization, and hyperpolarization. Figure out which one is which, then draw them in the order they occur in a cell that undergoes an action potential outside + Na* inside K* Na* Nat K Nat K Na potential: -80 mV outside + Na K* Na* inside Na+ K Nat Na* K+ potential: +30 mV outside Na Na Na Na* K+ inside K* Na* Kt potential: -70 mVarrow_forwardWhich of the following describe(s) the difference(s) between an EPSP and an IPSP? Select all that apply. An EPSP is actively reproduced as it travels along the axon, whereas an IPSP is a graded potential that decreases in strength with time and distance. An EPSP moves the cell closer to threshold, whereas an IPSP moves the cell away from threshold. An EPSP results from the movement of Cl- ions into the cell, whereas an IPSP results from movement of Na+ ions into the cell. An EPSP is a result of depolarization of the cell membrane, whereas an IPSP is a result of hyperpolarization of the membrane.arrow_forwardDrag and drop the following events of an action potential into its correct order: Voltage-gated Na* channels open and Na* floods into the neuron. Nat channels inactivate and voltage gated K* channels open. Ligand-gated Na* channels open. Voltage gated K* channels close and membrane potential approaches the resting membrane potential.arrow_forward
- You are examining a postsynaptic neuron that has a resting membrane potential of -70 mV and a threshold of -55 mV. If an inhibitory presynaptic neuron creates an IPSP of -5 mV and two excitatory presynaptic neurons have EPSPS of 10 and 12 mV, will the postsynaptic neuron fire an action potential if all three pre- synaptic neurons fire at the same time? In your answer describe EPSPS, IPSPs, temporal or spatial summation as appropriate.arrow_forwardWhich of the following statements about voltage gated channels is true? Voltage-gated sodium channels open at a higher (more positive) membrane potential than do potassium-gated channels Voltage-gated sodium channels open at a lower (more negative) membrane potential than do potassium-gated channels Sodium- and postassium-gated channels open at about the same membrane potential, but they have different effects because there are different numbers of the two kinds of channels in neuron cell membranesarrow_forwardThe correlation between neurons can explain the basis of the synaptic modification, that is, how much they can connect to each other or if they are not synchronized, how much they can lose or weaken their connections. Draw a picture of an excitatory synapse such as glutamatergic with its receptors between the pre- and postsynaptic neuron.arrow_forward
- Classify each phrase as describing ligand-gated ion channels, voltage-gated ion channels, or both. Ligand-gated ion channels a form of passive transport Voltage-gated ion channels include the acetylcholine receptor change conformation in response to changing membrane potential Answer Bank may participate in an action potential Both change conformation in response to a signal molecule bindingarrow_forwardChanges in intracellular Ca2+ is one of the main governing factors that determines the direction of plasticity (i.e., whether a synapse potentiates or depresses). Provide a general mechanism to explain how changes in intracellular Ca2+ can result in either synaptic depression or synaptic potentiation (refer to our discussion on kinases and phosphatases).arrow_forwardExplain what happens when an action potential reaches the axon terminus (terminal) by activating the receptors on the postsynaptic membrane. Explanation addressing the question above When an action potential, or nerve impulse, arrives at the axon terminal, it activates voltage-gated calcium channels in the cell membrane. Which is present at a much higher concentration outside the neuron than inside, rushes into the cell. The Ca2+ allows synaptic vesicles to fuse with the axon terminal membrane, releasing neurotransmitters into the synaptic cleft. The molecules of neurotransmitters diffuse across the synaptic cleft and bind to receptor proteins on the postsynaptic cell. Activation of postsynaptic receptors leads to the opening or closing of ion channels in the cell membrane. This may be depolarizing, making the inside of the cell more positive, or hyperpolarizing making the inside more negative depending on the ions involved. The excitatory and inhibitory postsynaptic potentials…arrow_forward
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