3. Living cells "pump" singly ionized sodium ions, Na+, from the inside of the cell to the outside across the membrane potential AVmembrane Vin - Vout= -70 mV. It is called pumping because work must be done to move a positive ion from the negative inside of the cell to the positive outside, and it must go on continuously because sodium ions "leak" back through the cell wall by diffusion. a. How much work must be done to move one sodium ion from the inside of the cell to the outside? b. At rest, the human body uses energy at the rate of approximately 100 W to maintain basic metabolic functions. It has been estimated that 20% of this energy is used to operate the sodium pumps of the body. Estimate to one significant figure the number of sodium ions pumped per second.

3. Living cells "pump" singly ionized sodium ions, Na+, from the inside of the cell to the outside across the membrane potential AVmembrane Vin - Vout= -70 mV. It is called pumping because work must be done to move a positive ion from the negative inside of the cell to the positive outside, and it must go on continuously because sodium ions "leak" back through the cell wall by diffusion. a. How much work must be done to move one sodium ion from the inside of the cell to the outside? b. At rest, the human body uses energy at the rate of approximately 100 W to maintain basic metabolic functions. It has been estimated that 20% of this energy is used to operate the sodium pumps of the body. Estimate to one significant figure the number of sodium ions pumped per second.

Physics for Scientists and Engineers, Technology Update (No access codes included)

9th Edition

ISBN:9781305116399

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter27: Current And Resistance

Section: Chapter Questions

Problem 27.38P: A Van de Graaff generator (see Fig. 25.23) is operating so that the potential difference between the...

See similar textbooks

Similar questions

A close analogy exists between the flow of energy by heat because of a temperature difference (see Section 19.6) and the flow of electric charge because of a potential difference. In a metal, energy dQ and electrical charge dq are both transported by free electrons. Consequently, a good electrical conductor is usually a good thermal conductor as well. Consider a thin conducting slab of thickness dx, area A, and electrical conductivity , with a potential difference dV between opposite faces. (a) Show that the current I = dq/dt is given by the equation on the left: ChargeconductionThermalconductiondqdt=A|dVdx|dQdt=kA|dTdx| In the analogous thermal conduction equation on the right (Eq. 19.17), the rate dQ/dt of energy flow by heat (in SI units of joules per second) is due to a temperature gradient dT/dx in a material of thermal conductivity k. (b) State analogous rules relating the direction of the electric current to the change in potential and relating the direction of energy flow to the change in temperature.
What does the term fibrillation mean in connection with heart function? Give two important causes of heart fibrillation in human beings. How do pacemakers and defibrillators help to prolong life for patients suffering from this condition?
Potential in a different kind of cell. A typical mammalian cell at 37 ∘C, with only potassium channels open, will have the following equilibrium: K+ (intracellular) ⇌ K+ (extracellular), with an intracellular concentration of 150 mM K+, and 4.0 mM K+ in the extracellular fluid. What is the potential, in volts, across this cell membrane? Note: in this case, n = the charge on the ion, and Eo for a concentration cell = 0.00 V.
1. The Atmos clock(the so-called perpetual motion clock) gets its name from the fact that it runs off pressure vacations in the atmosphere, which drive a belows containing a mixture of gas and liquid ethyl chloride. Because the power to drive these clocks is so limited, they must be very efficient. In fact, a single 60.0 W lightbulb could power 240 million Atmos clocks simultaneously. Find the amount of energy, in joules, required to run an Atmos clock for one day. Explain and draws.
Voltage across the resting membrane potential…A) Can be described by the Nernst equation.B) Is established by a difference in charges across the cell membrane, with the outside more negative than the inside.C) Defines the driving force for flow of a particular ion across the cell membrane, given its equilibrium potentialD) Is equally dependent on the flow of potassium and sodium ions through leak channels across the cell membrane.E) Stays the same during an action potential.
2) Estimate the rate at which energy flows from a gasoline pump to a motor vehicle during a “ fill-up. ” Express your answer in kW. If this rate of energy delivery were electric power, roughly how many people would it serve, assuming a typical US residential community? Make the following assumptions: the HHV of 1 gallon of gasoline is 145,000 Btu; it takes 5 minutes to fill up a 16-gallon auto tank; and a 1 GW e electrical plant serves a residential community of 1 million people.
The problem gives the answer to be v final=sqrt(1.2gh+v^2). I don't understand how to work this problem.
To measure signal propagation in a nerve in the arm, the nerve is triggered near the armpit. The peak of the action potential is measured at the elbow and then, 4.0 ms later, 24 cm away from the elbow at the wrist.a. What is the speed of propagation along this nerve?b. A determination of the speed made by measuring the time between the application of a stimulus at the armpit and the peak of an action potential at the elbow or the wrist would be inaccurate. Explain the problem with this approach, and why the noted technique is preferable.
(II) A neuron is stimulated with an electric pulse. The actionpotential is detected at a point 3.70 cm down the axon0.0052 s later. When the action potential is detected 7.20 cmfrom the point of stimulation, the time required is 0.0063 s.What is the speed of the electric pulse along the axon? (Whyare two measurements needed instead of only one?)
Suppose that you apply an external voltage (from a battery) to a pn junction where the n-doped part is connected to the positive terminal of the battery while the p-side is connected to the negative terminal of the battery.(a) What happens to the depletion region and why?(b) What happens to the internal electric field?(c) What happens to the current across the junction?
In a cell membrane with a thickness of 4.5 nm there is an electric field of 1.4 x 10 ^ 7 V / m oriented towards the interior of the cell. (a) What total work does a Na / K pump have to do during a normal cycle where it brings two K + ions into the cell and takes out three Na + ions? (b) The energy required is provided by the consumption of one molecule of adenosine triphosphate (ATP). Knowing that one mole ATP can release 30.5 KJ, estimate the efficiency of the Na / K pump. (please show steps, formulas and explanation for my own understanding. Thankyou) Answer: (a) 1.1 x 10-20; (b) 19.9%
In a certain region of space, the electric field is zero. From this fact, what can you conclude about the electric potential in this region? (a) It is zero, (b) It does not vary with position. (c) It is positive. (d) It is negative. (e) None of those answers is necessarily true.