Loose Leaf For Integrated Principles Of Zoology
18th Edition
ISBN: 9781260411140
Author: Cleveland P Hickman Jr. Emeritus, Susan L. Keen, David J Eisenhour Professor PhD, Allan Larson, Helen I'Anson Associate Professor of Biology
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 33, Problem 3RQ
The concentration of potassium ions inside a nerve cell membrane is higher than the concentration of sodium ions outside the membrane, yet the inside of the membrane (where the cation concentration is higher) is negative to the outside. Explain this observation in terms of permeability properties of the membrane.
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The concentration of potassium ions inside a nerve cell membrane is higher than the concentration of sodium ions outside the mem-brane, yet the inside of the membrane (where the cation concentra-tion is higher) is negative to the outside. Explain this observation in terms of permeability properties of the membrane.
There are differences in Na+, K+, and Cl- ion concentrations across the membrane. Knowing that ions like to flow down their respective concentration gradients explain how the movement of Cl- and K+ ions can result in membrane hyperpolarization.
Draw the current changes caused by a single voltage gated Potassium channel when the
membrane is voltage-clamped at different voltage values (see below). Assume an
equilibrium potential for potassium of -70mV and don't worry about exact values for the
currents (approximations are fine). Label the axes on the traces and describe how the
dynamics of individual voltage gated potassium channels come together to form the
macroscopic K+ currents during depolarization. .
a. @Resting Membrane Potential = -70 mV
b. @Voltage Step = -20 mV
c. @Voltage Step = +50mV
Chapter 33 Solutions
Loose Leaf For Integrated Principles Of Zoology
Ch. 33 - Define the following terms: neuron, axon,...Ch. 33 - Glial cells far outnumber neurons and contribute...Ch. 33 - The concentration of potassium ions inside a nerve...Ch. 33 - What ionic and electrical changes occur during...Ch. 33 - Explain different ways in which invertebrates and...Ch. 33 - Why is the sodium-potassium pump indirectly...Ch. 33 - Prob. 7RQCh. 33 - Prob. 8RQCh. 33 - Prob. 9RQCh. 33 - Prob. 10RQ
Ch. 33 - Prob. 11RQCh. 33 - Prob. 12RQCh. 33 - Prob. 13RQCh. 33 - Prob. 14RQCh. 33 - Chemoreception in vertebrates and insects is...Ch. 33 - What is the vomeronasal organ and what activity...Ch. 33 - Explain how ultrasonic detectors of certain...Ch. 33 - Outline the place theory of pitch discrimination...Ch. 33 - Explain how the semicircular canals of the ear are...Ch. 33 - Contrast the structure and functioning of the...Ch. 33 - Explain what happens when light strikes a...Ch. 33 - Prob. 22RQCh. 33 - Prob. 1FFT
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- One of the important uses of the Nernst equation is in describing the flow of ions across plasma membranes. Ions move under the influence of two forces: the concentration gradient (given in electrical units by the Nernst equation) and the electrical gradient (given by the membrane voltage). This is summarized by Ohms law: Ix=Gx(VmEx) which describes the movement of ion x across the membrane. I is the current in amperes (A); G is the conductance, a measure of the permeability of x, in Siemens (S), which is I/V;Vm is the membrane voltage; and Ex is the equilibrium potential of ion x. Not only does this equation tell how large the current is, but it also tells what direction the current is flowing. By convention, a negative value of the current represents either a positive ion entering the cell or a negative ion leaving the cell. The opposite is true of a positive value of the current. a. Using the following information, calculate the magnitude of Na [ Na+ ]0=145mM,[ Na+ ]i=15mM,Gna+=1nS,Vm=70mV b. Is Na+ entering or leaving the cell? c. Is Na+ moving with or against the concentration gradient? Is it moving with or against the electrical gradient?arrow_forwardDescribe the contribution of each of the following to establishing and maintaining membrane potential: (a) the Na+K+ pump, (b) passive movement of K+ across the membrane, (c) passive movement of Na+ across the membrane, and (d) the large intracellular anions.arrow_forwardif an object b has a plasma sodium concentration of 135mOsm/L and an intracellular concentration of 4mOsm/L. It also has a plasma concentration of potassium of 20mOsm/L and an intracellular concentration of 200mOsm/L. studies identify that the cells have a permeability to potassium that is 10 times greater than sodium. What is the resting membrane potentialarrow_forward
- Ions like K+ cannot diffuse directly across the membrane. They need open ion channels to cross the membrane. Explain why.arrow_forwardThe resting membrane potential is a negative value because of:arrow_forwardThe action potential is split into 4 parts (A-D). For each part, 1. Describe what stimulated the channel responsible for this part, 2. what is the likely ion that is moving and 3. explain which direction the ion had to move to create the measured membrane potential.arrow_forward
- Hyperkalemia is a condition by which ECF potassium levels become too high (usually due to kidney failure). Consider the following questions about the consequence of hyperkalemia on membrane potential. How would hyperkalemia affect EK? Considering your answer to the previous question, how would hyperkalemia affect membrane potential?arrow_forwardIf an ion has the same concentration on both sides of the membrane, then Eion Will be:arrow_forwardCompare the resting membrane potential of a neuron with the potassium and sodium equilibrium potentials. Explain how this comparison relates to the relative permeabilities of the resting plasma membrane to these two ions.arrow_forward
- If sodium permeability were to increase compared to normal what would be the resulting effect on the membrane potential 1.The charge on the inside of the cell becomes less negative compared to resting conditions and hyperpolarizes 2.The charge on the inside of the cell becomes more negative compared to resting conditions and hyperpolarizes 3.The charge on the inside of the cell becomes less negative compared to resting conditions and depolarizes 4.The charge on the inside of the cell becomes more negative compared to resting conditions and depolarizesarrow_forwardThe membrane potential for an excitable cell membrane is -70 mV, for sodium ions the Nernst equilibrium potential is +50 mV, the conductivity of the single sodium channel is 10 pS. What is the electrochemical potential difference that is the driving force for sodium ions to migrate? How much current flows through an open sodium channel under these conditions?arrow_forwardExplain why reticular fibers are also termed as argyrophilic fibers and lattice fibersarrow_forward
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