Human Physiology: An Integrated Approach (8th Edition)
8th Edition
ISBN: 9780134605197
Author: Dee Unglaub Silverthorn
Publisher: PEARSON
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Textbook Question
Chapter 8, Problem 31RQ
An unmyelinated axon has a much greater requirement for ATP than a myelinated axon of the same diameter and length. Can you explain why?
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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.
Unmyelinated axons conduct action potentials without decrement, but when myelinated axons lose myelin in demyelinating diseases such as multiple sclerosis, conduction of action potentials is blocked. Why?
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.
Chapter 8 Solutions
Human Physiology: An Integrated Approach (8th Edition)
Ch. 8.1 - Organize the following terms describing functional...Ch. 8.2 - Where do neurohormone-secreting neurons terminate?Ch. 8.2 - What is the difference between a nerve and a...Ch. 8.2 - Draw a chain of three neurons that synapse on one...Ch. 8.2 - What is the primary function of each of the...Ch. 8.2 - Name the two glial cell types that form myelin....Ch. 8.3 - Given the values in Table 8.2, use the Nernst...Ch. 8.3 - Would a cell with a resting membrane potential of...Ch. 8.3 - Would the cell membrane depolarize or...Ch. 8.3 - Match each ions movement with the type of graded...
Ch. 8.3 - Prob. 11CCCh. 8.3 - What is the difference between conductance and...Ch. 8.3 - If you put ouabain, an inhibitor of the Na+-K+...Ch. 8.3 - The pyrethrin insecticides, derived from...Ch. 8.3 - When Na+ channel gates are resetting, is the...Ch. 8.3 - A stimulating electrode placed halfway down an...Ch. 8.3 - Place the following neurons in order of their...Ch. 8.4 - Prob. 18CCCh. 8.4 - Prob. 19CCCh. 8.4 - Prob. 20CCCh. 8.4 - Prob. 21CCCh. 8.4 - Prob. 22CCCh. 8.4 - Classify the H+-neurotransmitter exchange as...Ch. 8.4 - Prob. 24CCCh. 8.4 - Prob. 25CCCh. 8.4 - Is Na+-dependent neurotransmitter reuptake...Ch. 8.5 - In Figure 8.24e, assume the postsynaptic neuron...Ch. 8.5 - In the graphs of Figure 8.24a, b, why doesnt the...Ch. 8.5 - Prob. 29CCCh. 8.5 - Prob. 30CCCh. 8 - List the three functional classes of neurons, and...Ch. 8 - Somatic motor neurons control __________, and...Ch. 8 - Prob. 3RQCh. 8 - Prob. 4RQCh. 8 - Prob. 5RQCh. 8 - Prob. 6RQCh. 8 - Axonal transport refers to the (a) release of...Ch. 8 - Match the numbers of the appropriate...Ch. 8 - Arrange the following events in the proper...Ch. 8 - List the four major types of ion channels found in...Ch. 8 - Prob. 11RQCh. 8 - An action potential is (circle all correct...Ch. 8 - Choose from the following ions to fill in the...Ch. 8 - What is the myelin sheath?Ch. 8 - List two factors that enhance conduction speed.Ch. 8 - Prob. 16RQCh. 8 - Draw and label a graph of an action potential....Ch. 8 - Prob. 18RQCh. 8 - Prob. 19RQCh. 8 - Create a map showing the organization of the...Ch. 8 - Prob. 21RQCh. 8 - Prob. 22RQCh. 8 - Prob. 23RQCh. 8 - Prob. 24RQCh. 8 - The presence of myelin allows an axon to (choose...Ch. 8 - Define, compare, and contrast the following...Ch. 8 - Prob. 27RQCh. 8 - Prob. 28RQCh. 8 - Prob. 29RQCh. 8 - Prob. 30RQCh. 8 - An unmyelinated axon has a much greater...Ch. 8 - The GHK equation is sometimes abbreviated to...Ch. 8 - In each of the following scenarios, will an action...
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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
- A neuron responds to adequate stimulation with _______, a type of self-propagating signal.arrow_forwardWhen action potentials arrive at a synapse between a neuron and another cell, they stimulate the release of molecules of a ________ that diffuse over to that cell.arrow_forwardView the University of Michigan Webscope (http://openstaxcollege.org/l/nervefiber) to see an electron micrograph of a cross-section of a myelinated nerve fiber. The axon contains microtubules and neurofilaments, bounded by a plasma membrane known as the axolemma. Outside the plasma membrane of the axon is the myelin sheath, which is composed of the tightly wrapped plasma membrane of a Schwann cell. What aspects of the cells in this image react with the stain that makes them the deep, dark, black color, such as the multiple layers that are the myelin sheath?arrow_forward
- Why does an action potential move in an all-or-nothing fashion down the length of an axon without stopping?arrow_forwardYou 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 zeroarrow_forwardAction potentials are changes in membrane potential that are localized to a small area of the plasma membrane. However, an action potential can trigger the formation of a new action potential nearby. This cycle can repeat to produce conduction of the action potential down the length of the axon. Explain this process.arrow_forward
- A damaged axon in the PNS may be able to regenerate only if the cell body is intact. why do you think that the cell body must be intact for regeneration to occur?arrow_forwardHelp me pleasearrow_forwardImagine a neuron that has a thousand axonal terminals synapsing on it. The majority of these axonal knobs are shown to be "firing." However, the neuron in question does not fire an action potential. What could be a possible explanation as to why this could be?arrow_forward
- An action potential can only be propagated along a myelinated axon. True or False?arrow_forwardThe neuron resting potential diagram is confusing to me. For the supposed sodium potassium channel in purple, how come the sodium ions are going outside of the cell instead of inside? How is it that there is a higher potassium concentration inside of the cell at this time if there are more leaky potassium channels (which should be pumping the potassium ions outside)?arrow_forwardWhy doesn’t an action potential that is propagated down an axon go in the reverse direction ( give a molecular explanation; what channels are involved)arrow_forward
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