An 82-year-old woman is brought to the emergency room complain- ing of nausea, vomiting, muscle cramps, and generalized weakness. Labo- ratory analysis reveals significant hyperkalemia. Elevations of extracellular potassium ion concentration will have which of the following effects on nerve membranes? a. The membrane potential will become more negative b. The sodium conductance will increase c. The potassium conductance will increase d. The membrane will become more excitable e. The Na*-K* pump will become inactivated

An 82-year-old woman is brought to the emergency room complain- ing of nausea, vomiting, muscle cramps, and generalized weakness. Labo- ratory analysis reveals significant hyperkalemia. Elevations of extracellular potassium ion concentration will have which of the following effects on nerve membranes? a. The membrane potential will become more negative b. The sodium conductance will increase c. The potassium conductance will increase d. The membrane will become more excitable e. The Na-K pump will become inactivated

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

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter3: The Plasma Membrane And Membrane Potential

Section: Chapter Questions

Problem 2SQE: One of the important uses of the Nernst equation is in describing the flow of ions across plasma...

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Extracellular fluids have relatively? A. high sodium and low potassium levels. B .high sodium and high potassium levels. C. higher concentrations of potassium, magnesium, phosphate, and D. sulfate ions. E. low sodium and low potassium levels. F. low sodium and high potassium levels.
if 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 potential
1)Where are neurotransmitters released from? A) dendrites B) axon terminal C) nodes of Ranvier D) postsynaptic membrane E) presynaptic membrane 2) What is the function of antidiuretic hormone? A) It increases the permeability of the collecting ducts to sodium, so more is reabsorbed B) It causes a high volume of less concentrated urine to be produced C) It increases the permeability of the collecting ducts to water, so more is reabsorbed. 3)Inhibitory neurotransmitters would NOT be expected to A) bind to receptors B) open K+ channels C) open Na+ channels D) hyperpolarize the membrane 4) In countercurrent exchange The flow of fluids in opposite directions maintains a favorable diffusion gradient along the length of an exchange surface Oxygen is exchanged for Carbon Dioxide Double circulation keeps oxygenated and deoxygenated blood separate…
Which of the following is ther eason why the potassium leaves the cell readily at the peak of the action potential?A) The sodium-potassium pumps work hard to return potassium to the extracellular fluid. B) Diffusion will continue to push potassium into the cell, but electrostatic pressure will move potassium out of the cell. C) Diffusion will push potassium out of the cell, but electrostatic pressure continues to attract potassium to the interior of the cell. D) Both diffusion and electrostatic pressure will cause potassium to exit the cell.
At the membrane of an axón, the action potential is -60 mV for K+ ions. Calculate the external and internal concentration ratios.
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.
The cleft is a flat disk between the two membranes, radius L= 250 nm and thickness d=20 nm. The neurotransmitter reached the receptor (AChR) within 0.2microseconds. Find the diffusion coefficient D and calculate the mean time at which A reaches AChE (mind the dimensionality). Present D in cm2/s.
The resting membrane potential of a neuron or muscle cell is a. equal to the potassium equilibrium potential. b. equal to the sodium equilibrium potential. c. somewhat less negative than the potassium equilibrium potential. d. somewhat more positive than the sodium equilibrium potential. e. not changed by stimulation.
How is the normal concentration of sodium and potassium relative to intracellular fluid and interstitial fluid maintained by the body? A. Sodium-potassium pump B. Sodium and potassium carrier-mediated channels C. Sodium and potassium concentration gradient D. Sodium and potassium leakage channels
Which of the following statements (s) about the ESA is not true? a) ENS can stimulate the release of hydrochloric acid b) Parasympathetic nerve pathways can stimulate ENS c) ENS operates through local control d) The neuron in the ENS cannot affect motility without being directly linked to the CNS e) ENS consists of sensory and motor neurons
Which of the following does not influence (i.e has no impact on) the value of the Nernst potential for Na+? The extracellular Na+ concentration The intracellular Na+ concentration The charge on Na+ The number of Na+ channels open
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?