Fill in the diagram, your illustration should demonstrate for each phase of the AP: 1. The relative concentration of K and Na 2. The relative voltage across the membrane 3. Any movement across the membrane of K and NA 4. The three kinds of channels in the membrane, and their state (open or closed) 5. Finally, indicate on the graph of the AP which phases correspond to hyper- polarization and which phases correspond to de- polarization

Fill in the diagram, your illustration should demonstrate for each phase of the AP: 1. The relative concentration of K and Na 2. The relative voltage across the membrane 3. Any movement across the membrane of K and NA 4. The three kinds of channels in the membrane, and their state (open or closed) 5. Finally, indicate on the graph of the AP which phases correspond to hyper- polarization and which phases correspond to de- polarization

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter4: Principles Of Neural And Hormonal Communication

Section4.3: Action Potentials

Problem 2CYU

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Assume that a membrane permeable to Na+ but not to Cl- separates two solutions. The concentration of sodium chloride on side 1 is higher than on side 2. Which of the following ionic movements would occur? a. Na+ would move until its concentration gradient is dissipated (until the concentration of Na+ on side 2 is the same as the concentration of Na+ on side 1). b. Cl- would move down its concentration gradient from side 1 to side 2. c. A membrane potential, negative on side 1, would develop. d. A membrane potential, positive on side 1, would develop. e. None of the preceding is correct.
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?)
Which 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 membranes
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.
Draw details of the repolarization phase of an action potential from the following descriptions of the sequences of AfterHyperPolarization (AHP) and AfterDePolarization (ADP) sequences. Make the distinct phases clear and noticeable (5 % each) A complex AHP consisting of a first component AHP, an ADP, and a second component AHP before repolarization to resting membrane potential a first fast AHP component, followed by a slower AHP, followed by a fast ADP, and a second late AHP component before repolarization to rest
If a cell with the following ion concentrations had a resting membrane potential of -40mV which of the following can you conclude? Extracellular: Cl- = 110 mM, Na+ = 145 mM, K+ = 5mM. Intracellular Cl- = 20 mM, Na+ = 10 mM, K+ = 140mM a) At rest it is only permeable to potassium b) At rest it has some permeability to more than one of these ions c) At rest it is only permeable to chloride d) Rest it is not permeable to sodium
The resting membrane potential…A) Can be approximated using the Goldman-Hodgkin-Katz equation.B) Represents a difference in charges across the cell membrane, resulting mostly from the passive flow of Na+ions.C) Has no influence on the driving force that acts on different ions across the cell membrane.D) Is equally dependent on the concentration gradients of potassium and sodium across the cell membrane.E) Becomes hyperpolarized during an excitatory graded potential.
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.
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?
Describe the contribution of each of the following to the establishment and maintenance of membrane potential: Part A Na+K+ Pump Passive movement of K+ across the membrane Passive movement of Na+ across the membrane Part B Resting membrane potential is approximately -70mV. Explain what resting membrane potential is and what -70mV refers to.
You attempt to generate an IV plot for GABA channels in cultured neurons. You apply pentobarbital and perform voltage steps but see no current at any voltage. Which of the following would explain your findings? Concentration of pentobarbital is too low GABA is not present in your solutions Cl- concentration is equal on both sides of the membrane None of the above
The following graph represents a membrane potential recording in the dark, then during a brief flash of flight at the time indicated by the arrow. This could be a recording from a: a) rod cell b) bipolar cell c) ganglion cell d) any of the above