# Is the concentration outside and inside the neuron important?

• harrow275
In summary, the question asks for the amount of power needed to produce a flow of Na+ ions against a +25.2 mV potential difference in an axon that is 11.7cm long and 19.6um in diameter. Multiple attempts were made to solve this problem, including calculating resistance using the given concentration and diameter, and using the work-energy theorem to find the energy needed for the task. However, the missing factor of time makes it difficult to determine the exact amount of power required.
harrow275

## Homework Statement

During the action potential, Na+ ions move into the cell at a rate of about 2.98×10-7mol/m2/s. How much power must be produced by the active transport system to produce this flow against a +25.2 mV potential difference? Assume that the axon is 11.7cm long and 19.6um in diameter.

Given Length, and Diameter. With this we can find resistance BUT we are not given rho so I'm not really sure what to do with the numbers. We are given the potential difference, and I converted mV to V. We are given a current of 2.98x10^-7 mol/m2/s.

## Homework Equations

Is the concentration outside and inside the neuron important?
Should a converstion be made from mol/m2/s to charge/s since current is C/s?

## The Attempt at a Solution

I have tried three different ways of figuring out the power. First I tried to multiply the V by and I given but that didn't work. I tried to calculate R using the concentration inside and outside the cell (for rho) then using the diameter(turned radius) and the length to find R. Then used R to find power.

I honestly have no idea where to go from here...

Try and find the Force required to move the ions against the potential difference. Then relate it to work using the Work-Energy Theorem. Once you have the energy needed, you should be able to find out how much power is needed because you're given the rate at which the ions are moving in the transport system. Power is just the rate at which work is done.

Good luck.

So I am able to find the work using W=qV...but in order to find power won't I need time? Since W/t=P, how would I find the time?

## 1. What is the concentration gradient?

The concentration gradient refers to the difference in concentration of a substance between two areas. In the context of a neuron, it refers to the difference in concentration of ions (such as sodium and potassium) between the inside and outside of the cell.

## 2. Why is the concentration outside and inside the neuron important?

The concentration difference between the inside and outside of a neuron is crucial for maintaining the resting membrane potential, which is the electrical potential of the cell when it is not actively sending signals. This concentration gradient also plays a role in the propagation of action potentials, which are the electrical signals that allow neurons to communicate with each other.

## 3. How is the concentration gradient maintained?

The concentration gradient is maintained through the actions of ion channels and pumps in the cell membrane. These proteins allow ions to move in and out of the cell, which helps to maintain the proper concentration levels. Additionally, the cell constantly uses energy to actively transport ions against their concentration gradient in order to maintain the proper balance.

## 4. What happens if the concentration gradient is disrupted?

If the concentration gradient is disrupted, it can lead to problems with the functioning of the neuron. For example, if there is a decrease in the concentration of ions outside of the cell, it can result in a decrease in the resting membrane potential, making it more difficult for the neuron to generate action potentials. Similarly, an increase in ion concentration outside the cell can make it easier for the neuron to generate action potentials, potentially leading to abnormal levels of activity.

## 5. Can changes in the concentration gradient affect brain function?

Yes, changes in the concentration gradient can definitely affect brain function. Any disruption in the proper balance of ions can lead to issues with the transmission of signals between neurons, which can impact various cognitive and physiological processes. For example, imbalances in potassium levels outside the cell have been linked to seizures, and disruptions in sodium levels can affect mood and behavior.

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