Anatomy & Physiology (6th Edition)
6th Edition
ISBN: 9780134156415
Author: Elaine N. Marieb, Katja N. Hoehn
Publisher: PEARSON
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Chapter 11, Problem 21SAQ
Since at any moment a neuron is likely to have thousands of neurons releasing neurotransmitters at its surface, how is neuronal activity (to fire or not to fire) determined?
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Since at any moment a neuron is likely to have thousands of neurons releasing neurotransmitters at its surface, how is neuronal activity (to fire or not to fire) determined?
Let’s say the synapses of a neuron’s dendrites are filled with glutamate-gated channels which, when activated by glutamate, cause an excitatory postsynaptic potential (EPSP) in the neuron. In one instance, glutamate is released at all of the synapses simultaneously and this leads to an action potential in the neuron.
A) What type of summation of PSPs is this? Why?
B) List the sequence of steps that occur starting from binding of glutamate to the glutamate-gated channels at the synapses and ending with the membrane potential at the axon hillock returning to resting potential at the end of the action potential. (Include all the changes in voltage-gated channels underlying the action potential.)
Cystic fibrosis is a degenerative disease that causes the progressive breakdown of the
myelin sheaths around the axons of neurons.
Which of the following best describes the likely effect of cystic fibrosis on neuronal
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B
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D
an inhibition in the release of neurotransmitters at the synaptic terminal
a decrease in the conduction speed of the action potential along neuronal axons
an unstoppable generation of action potential in affected neurons
an inhibition in the generation of action potentials at neuronal dendrites
Chapter 11 Solutions
Anatomy & Physiology (6th Edition)
Ch. 11.1 - What is meant by integration, and does it...Ch. 11.1 - Which subdivision of the PNS is involved in (a)...Ch. 11.2 - Which type of neuroglia controls the extracellular...Ch. 11.2 - Which two types of neuroglia form insulating...Ch. 11.3 - How does a nucleus within the brain differ from a...Ch. 11.3 - How is a myelin sheath formed in the CNS, and what...Ch. 11.3 - Which structural and functional type of neuron is...Ch. 11.3 - MAKING CONNECTIONS Which part of the neuron is its...Ch. 11.4 - For an open channel, what factors determine in...Ch. 11.4 - Prob. 10CYU
Ch. 11.5 - What determines the size of a graded potential?Ch. 11.6 - Which is bigger, a graded potential or an action...Ch. 11.6 - An action potential does not get smaller as it...Ch. 11.6 - Why does a myelinated axon conduct action...Ch. 11.6 - If an axon receives two stimuli close together in...Ch. 11.7 - Events at a chemical synapse usually involve...Ch. 11.7 - What structure joins two neurons at an electrical...Ch. 11.8 - Which ions flow through chemically gated channels...Ch. 11.8 - Prob. 19CYUCh. 11.9 - Prob. 20CYUCh. 11.9 - Why is cyclic AMP called a second messenger?Ch. 11.10 - Which types of neural circuits would give a...Ch. 11.10 - Prob. 23CYUCh. 11.10 - What pattern of neural processing occurs when we...Ch. 11 - Which of the following structures is not part of...Ch. 11 - Match the names of the supporting cells found in...Ch. 11 - Assume that an EPSP is being generated on the...Ch. 11 - Prob. 3MCCh. 11 - The velocity of nerve impulse conduction is...Ch. 11 - Chemical synapses are characterized by all of the...Ch. 11 - Biogenic amine neurotransmitters include all but...Ch. 11 - Prob. 8MCCh. 11 - Inhibition of acetylcholinesterase by poisoning...Ch. 11 - The anatomical region of a multipolar neuron where...Ch. 11 - An IPSP is inhibitory because (a) it...Ch. 11 - Identify the neuronal circuits described by...Ch. 11 - Explain both the anatomical and functional...Ch. 11 - (a) Describe the composition and function of the...Ch. 11 - (a) What is myelin? (b) How does the myelination...Ch. 11 - (a) Contrast unipolar, bipolar, and multipolar...Ch. 11 - What is the polarized membrane state? How is it...Ch. 11 - Describe the events that must occur to generate an...Ch. 11 - Prob. 19SAQCh. 11 - (a) Explain the difference between an EPSP and an...Ch. 11 - Since at any moment a neuron is likely to have...Ch. 11 - The effects of neurotransmitter binding are very...Ch. 11 - Prob. 23SAQCh. 11 - Prob. 24SAQCh. 11 - Elaine Sawyer, 35, was on her way to the local...Ch. 11 - Elaine Sawyer, 35, was on her way to the local...Ch. 11 - Elaine Sawyer, 35, was on her way to the local...Ch. 11 - Elaine Sawyer, 35, was on her way to the local...Ch. 11 - Elaine Sawyer, 35, was on her way to the local...
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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. thanks a lot in advance:)arrow_forwardWhich statement is true regarding the neuron synapse? B) binging of a neurotransmitter on the postsynaptic neuron membrane can generate an action potential in that neuron C) the binding of a neurotransmitter always causes an excitatory effect on that cell, never inhibitory D) the presynaptic and pastsynaptic neuron membranes are not physically separatedarrow_forwardHelp mearrow_forward
- Which of the following is the role of axonal Calcium (Ca2+) channels in neuronal communication at the synapse? a) they inhibit the action potential causing it to stop b) Calcium channels have no role in this process c) by allowing calcium to exit the cell, they promote the propagation of action potential across the synapse by creating depolarization d) by blocking calcium entrance, they mediate the contraction of presynaptic axon to facilitate movement e) when they open, calcium enters the presynaptic terminal, promoting fusion of neurotransmitter vesicles with presynaptic membrane, and release of neurotransmitters to the synaptic cleftarrow_forwardHow do neurotransmitters directly affect the postsynaptic neuron? A)They cause a change in the electrical potential, exciting the neuron and causing it to fire b)They cause a change in the electrical potential, either exciting or inhibiting the next neuron. C)They cause a change in the electrical potential, inhibiting the neuron and stopping it from fi d)They connect with the appropriate receptor on the postsynaptic neuronarrow_forwardWhen an impulse arrives at the synapse, the synaptic vesicles open and release neurotransmitters into the cleft within a thousandth of a second. Within another ten thousandth of a second, these molecules have diffused across the cleft and bound to receptor sites in the effector cell. In what two ways is transmission across a synapse terminated so that the neuron’s signal is concluded?arrow_forward
- Photoreceptor cells form glutamatergic synapses onto bipolar cells and when photoreceptor cells are depolarized the release of glutamate into the synapse is increased. One class of bipolar cells, (called OFF bipolar cells) have excitatory glutamate receptors in their post-synaptic specialization. What happens to the membrane potential of OFF bipolar cells when photoreceptors are illuminated?arrow_forwardNeuron A is an inhibitory neuron that is activated when the person feels heat in the tip of their index finger. Neuron A sends signals to neuron B (the postsynaptic neuron). First consider how a stimulus impacts the firing rate of neuron A. For example, when the person touches ice with their index finger vs. when the person touches a hot cup of coffee with their index finger? How would each of these impact the frequency of action potentials, the size of action potentials and the amount of neurotransmitter released. Second, consider Drug-D that causes all sodium channels in neurons to close immediately. How would taking Drug-D affect the firing rate of neuron A when the person touches a hot pan? In turn, how would this affect the firing rate of post-synaptic neuron B? Rubric: Impact of heat on A Impact of ice on A ( Impact of drug X on A Impact of drug X on B 1arrow_forwardA postsynaptic neuron has three presynaptic inputs from neurons X, Y, and Z. When X and Y are stimulated simultaneously and repeatedly, the postsynaptic neuron reaches threshold and undergoes an action potential. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential of the postsynaptic neuron. Which of the following is correct? Select one: A. The simultaneous stimulation of X and Z is an example of temporal summation. O B. The simultaneous stimulation of X and Y is an example of temporal summation. O C. The repeated rapid stimulation of X is an example of spatial summation. O D. The stimulation of Y causes an IPSP in the postsynaptic neuron. O E. The stimulation of Z causes a hyperpolarization in the postsynaptic neuron.arrow_forward
- Which of the following is true regarding the difference between graded and action potentials? a.) Action potential occur only when the surface of the neuron is myelinated, but graded potentials occur in both in both myelinated and non-myelinated neurons. b.) The magnitude of action potential depends on the magnitude of the stimulus, whereas graded potentials are all or none. c.) The magnitude of graded potential depends on the magnitude of the stimulus, whereas action potentials are all or none.arrow_forwardWhich of the following statements concerning synapses is FALSE? O A) Modulation of synaptic strength can be presynaptic of postsynaptic B) High frequency stimulation in the presynaptic neuron often leads to DECREASED neurotransmitter release O C) Modulation of synaptic strength can either be short term, lasting seconds, or long term, lasting as long as a lifetime. D) Agonists are drugs that mimic neurotransmitters and antagonists are drugs that block the action of neurotransmitters O E) Certain drugs prevent the reuptake of neurotransmitter from the synapsearrow_forwardHelp me pleasearrow_forward
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