Human Physiology
15th Edition
ISBN: 9781259864629
Author: Fox, Stuart Ira
Publisher: Mcgraw-hill Education,
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Chapter 7, Problem 30RA
Summary Introduction
To review:
1. The different states of voltage-gated ion channels and the differences between them.
2. The role of molecular biology/biochemistry in understanding the physiology of these channels.
Introduction:
The transportation of molecules or ions present in the extracellular fluid is regulated by different methods such as diffusion, facilitated diffusion, and active transport. Normal diffusion results in the flow of molecules or ions across the membrane from high concentration to low concentration. Facilitated diffusion results in the transport of molecules or ions through carrier proteins or channels present in the cell membrane with respect to their concentration gradient.
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Separately, draw a table using arrows to depict the appropriate magnitude and direction of the forces and ion fluxes at different membrane potentials for a ligand-gated channel that is equally permeable to both ion X+ and ion Y+. The equilibrium potential for ion X+ is -60 mV, and the equilibrium potential for ion Y+ is -20 mV. Which item best represents the forces and fluxes for a membrane potential of -40 mV (a, b, c, or d)? Upwards arrows means outward direction and downwards arrow means inward direction. The length of the arrow determines the magnitude.
Separately, draw a table using arrows to depict the appropriate magnitude and direction of the forces and ion fluxes at different membrane potentials for a ligand-gated channel that is equally permeable to both ion X+ and ion Y+. The equilibrium potential for ion X+ is -60 mV, and the equilibrium potential for ion Y+ is -20 mV.
Which item best represents the forces and fluxes for a membrane potential of +20 mV?
What is the difference between a ligand-gated channel (like H1 or the AChR) and a voltage gated channel?
Chapter 7 Solutions
Human Physiology
Ch. 7 - Draw a neuron, label its parts, and describe the...Ch. 7 - Distinguish between sensory neurons, motor...Ch. 7 - Describe the structure of the neurilemma, and...Ch. 7 - Explain how myelin sheaths are formed in the CNS....Ch. 7 - Explain what is meant by the blood-brain barrier....Ch. 7 - Define the terms depolarization and...Ch. 7 - Prob. 4bCPCh. 7 - Describe how gating of Na+andK+ in the axon...Ch. 7 - Prob. 5aCPCh. 7 - Prob. 5bCP
Ch. 7 - Prob. 6aCPCh. 7 - Describe the location of neurotransmitters within...Ch. 7 - Describe the sequence of events by which action...Ch. 7 - Explain how chemically regulated channels differ...Ch. 7 - Prob. 8CPCh. 7 - Prob. 9aCPCh. 7 - Prob. 9bCPCh. 7 - Prob. 10CPCh. 7 - Prob. 11CPCh. 7 - Prob. 12aCPCh. 7 - Prob. 12bCPCh. 7 - Prob. 13aCPCh. 7 - Prob. 13bCPCh. 7 - Prob. 14aCPCh. 7 - Describe the mechanism of action of glycine and...Ch. 7 - Give examples of endogenous opioid polypeptides,...Ch. 7 - Prob. 15bCPCh. 7 - Prob. 16CPCh. 7 - Prob. 17aCPCh. 7 - Prob. 17bCPCh. 7 - Prob. 17cCPCh. 7 - Prob. 1RACh. 7 - Prob. 2RACh. 7 - Prob. 3RACh. 7 - Prob. 4RACh. 7 - Repolarization of an axon during an action...Ch. 7 - As the strength of a depolarizing stimulus to an...Ch. 7 - Prob. 7RACh. 7 - Which of these is not a characteristic of synaptic...Ch. 7 - Prob. 9RACh. 7 - Prob. 10RACh. 7 - Prob. 11RACh. 7 - Prob. 12RACh. 7 - Prob. 13RACh. 7 - Prob. 14RACh. 7 - Prob. 15RACh. 7 - Prob. 16RACh. 7 - Prob. 17RACh. 7 - Which of these may be produced by the action of...Ch. 7 - Prob. 19RACh. 7 - In a step-by-step manner, explain how the...Ch. 7 - Prob. 21RACh. 7 - Prob. 22RACh. 7 - Prob. 23RACh. 7 - Prob. 24RACh. 7 - Once an EPSP is produced in a dendrite, how does...Ch. 7 - Prob. 26RACh. 7 - List the endogenous opioids in the brain and...Ch. 7 - Explain what is meant by long-term potentiation...Ch. 7 - Prob. 29RACh. 7 - Prob. 30RACh. 7 - Prob. 31RACh. 7 - Prob. 32RACh. 7 - Prob. 33RACh. 7 - Explain the nature of the endocannabinoids....Ch. 7 - Prob. 35RACh. 7 - Prob. 36RACh. 7 - Prob. 37RACh. 7 - Prob. 38RACh. 7 - Prob. 39RACh. 7 - Use the figure below (from figure 7.34) to answer...
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- Which of the following statements best describes the features of voltage-gated K+ channels? They consist of 4 subunits, are activated at the same time as voltage-gated Na+ channels, but do not inactivate. They consist of 4 subunits, are activated by depolarisation and close slowly during the refractory period. They have 24 membrane spanning alpha helices, 4 of which have positively charged amino acids which promote a conformational change in the channel following depolarisation. They consist of 4 subunits and are open at rest which causes the resting membrane potential to be close to the K+ equilibrium potential.arrow_forwardSeparately, draw a table using arrows to depict the appropriate magnitude and direction of the forces and ion fluxes at different membrane potentials for a ligand-gated channel that is equally permeable to both ion X+ and ion Y+. The equilibrium potential for ion X+ is -60 mV, and the equilibrium potential for ion Y+ is -20 mV. Which item best represents the forces and fluxes for a membrane potential of -60 mV? Pick one of the four tables in the included image please for your answer.arrow_forwardname the three ways in which an ion channel can be gated.arrow_forward
- The resting membrane potential…A) Can be approximated using the Nernst equation.B) Is established by a difference in charges across the cell membrane, with the inside more positive than the outside.C) Has no influence on the driving force for flow of a particular ion across the cell membrane.D) Is more dependent on the passive flow of potassium vs. sodium ions through leak channels across the cell membrane.E) Stays the same during an action potential.arrow_forwardDefine the term voltage-gated ion channels?arrow_forwardExplain how the crystal structures of potassium ion channels suggest the way in which the voltage-sensing domains interact with other parts of the proteins to open and close the ion channels. How does this structure-function relationship apply to other voltage-gated ion channels?arrow_forward
- What properties of ion channels allow them to generate the large, rapid changes in membrane potential?arrow_forwardPlease explain what the resting membrane potential is and its value. Make sure you include all structures involved in the creation and maintenance of the resting membrane potential. Explanation addressing the question above Membrane potential is the difference in electric potential between the interior and the exterior of a biological cell. With respect to the exterior of the cell, typical values of membrane potential range from -40 mV to -80 mV. The membrane potential has two basic functions as a battery and transmitting signals between different parts of a cell. In non-excitable cells, the membrane potential is held at a relatively stable value, called the resting potential. The resting membrane potential of a neuron is about -70 mV. At rest, there are relatively more sodium ions outside the neuron and more potassium ions inside that neuron. It is determined by concentration gradients of ions across the membrane and by membrane permeability to each type of ion. Structure and…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_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_forwardDescribe in detail what resting membrane potential is and what role the sodium/potassium leakage channels and the sodium-potassium pump play in maintaining this potential.arrow_forwarddescribe what the resting membrane potential of a cell is. What is the resting membrane potential of neurons (give units)? What are the two factors that generate the resting membrane potential? Think of scenarios that change the factors that generate the resting membrane potential and how that would change the overall resting membrane potential.arrow_forward
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