Fundamentals of Anatomy & Physiology (11th Edition)
11th Edition
ISBN: 9780134396026
Author: Frederic H. Martini, Judi L. Nath, Edwin F. Bartholomew
Publisher: PEARSON
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Textbook Question
Chapter 12, Problem 18CP
Which of the following axons is myelinated: one that propagates action potentials at 50 meters per second, one that carries them at 1 meter per second?
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You generate action potentials in a neuron bathed in solution in a petri dish by applying a threshold-level depolarizing stimulus near its axon hillock. If the solution surrounding
the neuron contained 5mM K+, 150 mM Na+, and 0 mM Ca2+ which of the following would you expect?
The neuron would not be able to propagate action potentials down the entire length of the axon
The neuron would not release neurotransmitter from the axon terminal
The neurons action potentials would have an unusually long duration
The neuron would have a resting membrane potential of zero
Which of the following statements best describes the properties of a myelinated axons?
The axon has an even distribution of ion channels but it is covered by layers of myelin apart from short sections termed the nodes of Ranvier where there is no myelin.
The action potential is able to jump from node to node because the myelin sheath increases the length constant. There are very few ion channels underneath the myelin.
The density of Na+ channels at the nodes of Ranvier is very high but there are no K+ channels in myelinated axons.
The myelin sheath increases the rate of action potential conduction because the action potential underneath the myelin sheath travels faster than an action potential in an unmyelinated axon.
If a neuron is stimulated simultaneously by 2 stimuli at its dendrites (one generates a very large hyperpolarizing potential and the other generates a very small depolarizing potential). What would happen to this neuron?
Group of answer choices
The summation of these two graded potentials will generate an action potential and this action potential will travel down the axon.
Summation of these two graded potentials will cause the membrane potential at the axon hillock to be more negative.
These graded potentials will bring the resting membrane potential to 0 mV.
These graded potentials with opposite polarity would therefore generate two action potentials and they will travel along this neuron in opposite direction.
Chapter 12 Solutions
Fundamentals of Anatomy & Physiology (11th Edition)
Ch. 12 - Describe the three anatomical divisions of the...Ch. 12 - Describe the two functional divisions of the...Ch. 12 - Identify the two components of the efferent...Ch. 12 - Prob. 4CPCh. 12 - Name the structural components of a typical...Ch. 12 - Classify neurons according to their structure.Ch. 12 - Classify neurons according to their function.Ch. 12 - Prob. 8CPCh. 12 - Prob. 9CPCh. 12 - Prob. 10CP
Ch. 12 - Prob. 11CPCh. 12 - Prob. 12CPCh. 12 - Prob. 13CPCh. 12 - What effect would decreasing the concentration of...Ch. 12 - Define action potential.Ch. 12 - Identify the steps involved in the generation and...Ch. 12 - Prob. 17CPCh. 12 - Which of the following axons is myelinated: one...Ch. 12 - Prob. 19CPCh. 12 - Prob. 20CPCh. 12 - What effect would blocking voltage-gated calcium...Ch. 12 - Prob. 22CPCh. 12 - Prob. 23CPCh. 12 - Prob. 24CPCh. 12 - Prob. 25CPCh. 12 - Prob. 26CPCh. 12 - Prob. 27CPCh. 12 - LEVEL 1 Reviewing Facts and Terms 1. Label the...Ch. 12 - Prob. 2RQCh. 12 - Prob. 3RQCh. 12 - Prob. 4RQCh. 12 - The neural cells responsible for the analysis of...Ch. 12 - Depolarization of a neuron plasma membrane will...Ch. 12 - Prob. 7RQCh. 12 - Receptors that bind acetylcholine at the...Ch. 12 - What are the major components of (a) the central...Ch. 12 - Prob. 10RQCh. 12 - Prob. 11RQCh. 12 - If the resting membrane potential of a neuron is...Ch. 12 - Prob. 13RQCh. 12 - What is the difference between anterograde flow...Ch. 12 - What is the functional difference among chemically...Ch. 12 - State the all-or-none principle cf action...Ch. 12 - Prob. 17RQCh. 12 - Prob. 18RQCh. 12 - What are the structural and functional differences...Ch. 12 - Describe the events that occur during nerve...Ch. 12 - Prob. 21RQCh. 12 - Prob. 22RQCh. 12 - Prob. 23RQCh. 12 - In multiple sclerosis, there is intermittent and...Ch. 12 - Prob. 25RQCh. 12 - Which cells of the CNS are targeted by the polio...Ch. 12 - Prob. 2CC
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- Which of the following combinations of spatial summation of postsynaptic potentials (PSP) would result in an action potential in a typical neuron? The voltage given for each PSP is measured as it reaches the axon hillock. Axon A EPSP 25 mV & axon B IPSP 10 mV Axon A IPSP 25 mV & axon B EPSP 10 mV Axon A IPSP 5 mV & axon B IPSP 5 mV Axon A EPSP 5 mV & axon B EPSP 5 mVarrow_forwardWhich of the following would occur if a neuron was experimentally stimulated simultaneously at both ends? The action potentials would pass in the middle and travel to the opposite ends The action potentials would stop as they meet in the middle. The stronger action potential would override the weaker action potential. Summation would occur when the action potentials meet in the middle, resulting in a larger action potential.arrow_forwardWhich of the following statements is TRUE about the depolarization phase of action potential? Group of answer choices: Na-K pump initiates depolarization. Potassium ion channels quickly opens to allow efflux of ions. Depolarization is characterized by the movement of calcium ions out of the cell. Depolarization is primarily triggered by opening of sodium ion channels asap plsarrow_forward
- 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 hillockarrow_forwardTwo separate post-synaptic interneurons receive synaptic potentials from afferent neurons in the periphery. The dendrites of one these interneurons receive an excitatory post-synaptic potential (EPSP) and an inhibitory post-synaptic potential (IPSP) of equal magnitude at the same time. The dendrites of the other interneuron receive one excitatory post-synaptic potential that is the same sized as the EPSP and IPSP received by the other interneuronarrow_forwardTwo axons are tested for propagation velocities (speeds). One carries action potentials at 50 meters per second, the other at 1 meter per second. Which axon is myelinated?arrow_forward
- Which of the following would most likely occur if you experimentally depolarise the middle of an axon to threshold using an electronic probe? Question 24 options: an action potential will be initiated and proceed only in the normal direction toward the axon terminal no action potential will be initiated an action potential will be initiated and proceed only back toward the axon hillock two action potentials will be initiated and will proceed in opposite directionsarrow_forwardWhich of the following is NOT true regarding the changes that occur during an action potential. Check All That Apply When stimulus is sufficient to cause the threshold potential to be reached, the area stimulated opens its voltage-gated sodium channels.When stimulus is sufficient to cause the threshold potential to be reached, the area stimulated opens its voltage-gated sodium channels. After threshold is reached, the sodium ions move into the cell via the Na+/K+ pump, the inside of the cell becomes momentarily positive.After threshold is reached, the sodium ions move into the cell via the Na+/K+ pump, the inside of the cell becomes momentarily positive. At almost the same time as Na+ channels are closing, voltage-gated potassium channels open, allowing an increased movement of potassium ions out of the cellAt almost the same time as Na+ channels are closing, voltage-gated potassium channels open, allowing an increased movement of potassium ions out of the cell The…arrow_forwardBased on the graph, how soon could another action potential be easily initiated (at the end of the relative refractory period) after the first stimulus? (Base your answer to this question on the graph below depicting an action potential.) less than 0.5 msec 1 msec 2 msec 3 msec 4 msecarrow_forward
- Which 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_forwardIn the figure to the left, name the 4 phases of the action potential (Note: you have to write in where phase 4 occurs). Describe what happens in each phase with a focus on Na+ and K+ flow through channels and the membrane potential. Discuss the importance of threshold. How does this relate to the concept of APs being all or none?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
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