Human Physiology: From Cells to Systems (MindTap Course List)
9th Edition
ISBN: 9781285866932
Author: Lauralee Sherwood
Publisher: Cengage Learning
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Chapter 4, Problem 1TAHL
The rate at which the
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The extracellular concentration of Cl-Cl¯ is 123 mM and the
intracellular concentration is 4 mM. In which direction does Cl-CI¯|
flow through an open channel when the membrane potential is in
the -60 mV-60 mV to +30 mV+30 mV range?
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+
The following concentrations of Na+ and K+ ions: [Na+]o = 120 mM, [Na+]i = 6 mM,[K+]o = 2 mM, and [K+]i = 150 mM.
Assuming that the further at the peak of the action potential, PK: PNa is 1 : 12.
Calculate (Vm) at the peak of the action potential
Chapter 4 Solutions
Human Physiology: From Cells to Systems (MindTap Course List)
Ch. 4.1 - Name the two types of excitable tissue.Ch. 4.1 - Prob. 2CYUCh. 4.1 - State the factor responsible for triggering gate...Ch. 4.2 - Prob. 1CYUCh. 4.2 - Prob. 2CYUCh. 4.2 - Prob. 3CYUCh. 4.3 - Draw and label an action potential, indicating the...Ch. 4.3 - Prob. 2CYUCh. 4.3 - Prob. 3CYUCh. 4.3 - Prob. 4CYU
Ch. 4.4 - Explain why synapses operate only in the direction...Ch. 4.4 - Prob. 2CYUCh. 4.4 - Prob. 3CYUCh. 4.4 - Prob. 4CYUCh. 4.5 - Define target cell.Ch. 4.5 - Distinguish among the four types of extracellular...Ch. 4.5 - Outline the three general means by which binding...Ch. 4.5 - Prob. 4CYUCh. 4.6 - Distinguish between cytokines and eicosanoids.Ch. 4.6 - Discuss the roles of phospholipase A2,...Ch. 4.6 - Prob. 3CYUCh. 4.7 - Prob. 1CYUCh. 4.7 - Prob. 2CYUCh. 4.7 - Prob. 3CYUCh. 4.8 - Prob. 1CYUCh. 4.8 - Prob. 2CYUCh. 4 - Conformational changes in channel proteins brought...Ch. 4 - Prob. 2RECh. 4 - Prob. 3RECh. 4 - Prob. 4RECh. 4 - Second-messenger systems ultimately bring about...Ch. 4 - Each steroidogenic organ has all the enzymes...Ch. 4 - Prob. 7RECh. 4 - Prob. 8RECh. 4 - Prob. 9RECh. 4 - Prob. 10RECh. 4 - Prob. 11RECh. 4 - Prob. 12RECh. 4 - Prob. 13RECh. 4 - A common membrane-bound intermediary between the...Ch. 4 - Prob. 15RECh. 4 - Prob. 16RECh. 4 - Prob. 17RECh. 4 - Prob. 18RECh. 4 - Define the following terms: polarization,...Ch. 4 - Prob. 2UCCh. 4 - Prob. 3UCCh. 4 - Prob. 4UCCh. 4 - Compare the four kinds of gated channels in terms...Ch. 4 - Prob. 6UCCh. 4 - Prob. 7UCCh. 4 - Prob. 8UCCh. 4 - Prob. 9UCCh. 4 - Define signal transduction.Ch. 4 - Compare the tyrosine kinase and JAK/STAT pathways.Ch. 4 - Prob. 12UCCh. 4 - Prob. 13UCCh. 4 - Describe how arachidonic acid is converted into...Ch. 4 - Prob. 15UCCh. 4 - Prob. 16UCCh. 4 - Explain how the cascading effect of hormonal...Ch. 4 - Prob. 18UCCh. 4 - Answer the following questions regarding...Ch. 4 - Prob. 2SQECh. 4 - Prob. 3SQECh. 4 - Prob. 1ACRCh. 4 - The rate at which the Na+K+ pump operates is not...Ch. 4 - Which of the following would occur if a neuron...Ch. 4 - Prob. 3TAHLCh. 4 - Assume presynaptic excitatory neuron A terminates...Ch. 4 - Prob. 5TAHL
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- Describe 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_forwardConformational 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_forwardOne 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_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_forwardChloride ions (Cl-) behave a bit differently to Na+ and K+ in that most cells don't have active Cl- transporters. As a result, the concentration gradient for Cl- is not 'set' like it is for Na+ and K+. There are, however, a limited number of Cl- leak channels in the cell membrane. As a result, Eci generally matches resting membrane potential - around - 70mV. Considering this, answer the following questions. If Cl- can cross the cell membrane, is not being actively transported, and membrane potential is -70mV, will there be a concentration gradient for Cl-?arrow_forwardWhat happens to the membrane potential when Na+/K+ pump is active?arrow_forward
- The resting potential is dependent upon the electrochemical gradient for potassium ions because: The permeability of the resting membrane to potassium is higher than for other ions Of the activity of the sodium/potassium ATPase pump Cells contain largely potassium The permeability to sodium ions is very small except during action potentialsarrow_forwardA drug specifically blocks the Na+/K+ ATPase pump. What effect might this have on the action potential? O It will shorten the duration of the action potential as there will not be as many ions available to cross the membrane. None, as action potentials rely on channels for Na+ and K+ to cross the membrane, not pumps. It will not have an immediate effect, but eventually action potentials will stop as the Na+ and K+ gradients are depleted. It will make action potentials more likely to occur as the pump normally makes the cell more negative, so without it the membrane will reach threshold more easily.arrow_forwardWhat role do the Na+/K+ pumps play in establishing the resting membrane potential?arrow_forward
- Calculate the driving force for Na+, K+, and Ca2+ current in a neuron under physiological conditions.arrow_forwardAt rest, a neuron has a lower concentration of sodium than the surrounding fluid. The neuron also has a higher concentration of potassium inside the cell. The sodium-potassium ion pump is used to maintain the neuron in the resting state. Which of the following statements is true? A. Remaining at rest requires the use of ATP. B. Remaining at rest requires an input of sodium. C. Remaining at rest requires the activation of cotransporters. D Remaining at rest requires decreased permeability of the membrane.arrow_forwardThe normal concentrations for intracellular and extracellular potassium in a neuron are [K+]in = 150 mM and [K+]out = 5 mM, respectively. Due to an electrolyte imbalance, a patient has the following intracellular and extracellular concentrations of potassium: [K+]in = 140 mM and [K+]out =2 mM. Using the Nernst equation (Chapter 4), calculate the equilibrium potential for potassium in the cells with normal K+ distributions and of the diseased patient. Refer back to Question #1. Will it be easier or more difficult to generate an action potential in the diseased neuron as compared to the normal neuron? Why?arrow_forward
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