EBK HUMAN PHYSIOLOGY
8th Edition
ISBN: 9780134704227
Author: Silverthorn
Publisher: YUZU
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Chapter 8, Problem 18RQ
Summary Introduction
Introduction: The conduction of action potential is initiated by the change in the K+ concentration of blood, which affects the resting membrane potential. The rise in the action potential is due to the increase in the Na+ permeability, and the falling phase occurs due to the increase in the K+ permeability.
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The membrane potential labeled (0) is due to which of the following (when compared to (3) potential.
(A) voltage-gated Na+ channels
(B) voltage-gated K+ channels
(C) voltage-gated slow Ca++ channels
(D) voltage-gated fast Ca++ channels
(E) voltage-gated transient Ca++ channels
(F) funny channels
At the peak of the action potential, Vm is approximately -65 mV. Assuming normal intracellular and extracellular K+ concentrations (refer to the table),
(1) calculate the driving force (in mV) that acts on K+ ions
and
(2) use the information obtained in part 1 to determine the direction in which K+ ions will flow (i.e., into the cell or out of cell)
The extracellular sodium [Na+]0 is reduced in the saline bath. Following another current injection
in a neuron, the membrane potential changes were recorded.
a) Why has the membrane potential changed following the Na+ reduction?
b) Why has the current injection produced no action potentials?
c) How might you experimentally rescue action potential generation?
Chapter 8 Solutions
EBK HUMAN PHYSIOLOGY
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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- Conformational changes in channel proteins brought about by voltage changes are responsible for opening and closing Na+ and K+ gates during the generation of an action potential. (True or false?)arrow_forwardAssume 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_forwardRead the following statements (a) The resting nerve membrane is freely permeable to Na*, K* ions and negatively charged proteins. (b) The activity of Na* - K* pump is responsible for maintaining resting membrane potential. (c) The resting membrane is impermeable to negatively charged proteins present in the axoplasm. Choose the option representing correct statements. b only a and b b and c a, b and carrow_forward
- The following is a graph of membrane potential over time during an action potential. At which labeled point, A-D, would permeability to potassium (K+) be the greatest? A) B) C) D)arrow_forwardRefer to the graph showing the course of an action potential. Which of the numbered points along the graph represent the time when voltage-gated potassium channels are first activated? a) 1 b) 2 c) 3 d) 4 e) 5arrow_forwardwhich of the following would be true (more than one can be true)? a) summation of A and X would reach threshold b) summation of C and A would be a graded potential c) stimulation by A would depolarize cell d) stimulation by B would be a subthreshold depolarization e) summation of B and C would be a graded potential with the net value of 12 mV depolarizationarrow_forward
- Choose the correct answer: A) When the voltage gated K+ channels open K+ moves down its concentration gradient from the ECF to inside the cell. O B) The value for resting membrane potential is closer to the EK+ (Equilibrium potential for K+) than the ENa+ O C) When the membrane potential is at rest the membrane is more permeable to Na+ than it is to K+ O D) Closing of the voltage-gated Na+ channels increases the permeability of the membrane to Na+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_forwardWhich factors in the establishment of the membrane potential are considered in the Nernst equation? (i) Coulomb force; (ii) Ion concentration; (iii) Length of the axon; (iv) Number of dendrites; (v) Permeability of the cell membrane. Select one: a. (i), (iii), (iv) b. (ii), (iii) c. (ii), (iv), (v) d. (i), (ii)arrow_forward
- Which statement is true regarding the action potential process? 1) the repolarization phase must occur prior to depolarization 2) hyperpolarization allows for Na+ and K+ ions to move into and out of the cell 3) the action potential process only occurs at the nodes of ranvier in myelinated axons 4) depolarization occurs because voltage gated K+ channels allow K+ ions to rush into the cellarrow_forwardFigure 1 shows the action potential graph recorded from a rat neurone and the potential changes obtained from the rat neurone when the concentration of potassium ([K*]out) and calcium ([Ca²+]out) are varied extracellularly in the bathing solution. (i) In the resting state, is the neuronal permeability to potassium more than, less than or equal to that of the permeability to calcium? Explain your answer. (ii) Vm 'The calcium ion concentrations are lower inside the cell than outside.' Justify this statement based on the graphs and the Nernst equation assuming the temperature is at 25 °C. Vm 30 0 -30 30 0- -30 0 50 AP overshoot [K+ lout 100 150 time (msec) 30 RP Figure 1 0- -30 AP overshoot RP 200 250 AP overshoot {Ca²+ Jout RParrow_forwardNerve membrane hyperpolarization after an action potential a)Is the movement of membrane potential voltage below normal resting potential voltage. b) This Is mostly due to the slow-closing of K+ channels. c)Makes it more difficult to evoke another action potential. d) This Is mostly due to the slow-closing of Na+ channels.arrow_forward
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