Nerve impulses are electrical "signals" that pass through...

Nerve impulses are electrical "signals" that pass through neurons in the body. The electrical potential is created by the differences in the concentration of $\mathrm{Na}^{+}$ and $\mathrm{K}^{+}$ ions across the nerve cell membrane. We can think about this potential as being caused by a concentration gradient, similar to what we see in a concentration cell (keep in mind that this is a very simple explanation of how nerves work; there is much more involved in the true biologic process). A typical nerve cell has a resting potential of about $-70 \mathrm{mV}$. Let's assume that this resting potential is due only to the $\mathrm{K}^{+}$ ion concentration difference. In nerve cells, the $\mathrm{K}^{+}$ concentration inside the cell is larger than the $\mathrm{K}^{+}$ concentration outside the cell. Calculate the $\mathrm{K}^{+}$ ion concentration ratio necessary to produce a resting potential of $-70 . \mathrm{mV}$. $$\frac{\left[\mathrm{K}^{+}\right]_{\text {inside }}}{\left[\mathrm{K}^{+}\right]_{\text {outside }}}=?$$

Nerve impulses are electrical "signals" that pass through neurons in the body. The electrical potential is created by the differences in the concentration of $\mathrm{Na}^{+}$ and $\mathrm{K}^{+}$ ions across the nerve cell membrane. We can think about this potential as being caused by a concentration gradient, similar to what we see in a concentration cell (keep in mind that this is a very simple explanation of how nerves work; there is much more involved in the true biologic process). A typical nerve cell has a resting potential of about $-70 \mathrm{mV}$. Let's assume that this resting potential is due only to the $\mathrm{K}^{+}$ ion concentration difference. In nerve cells, the $\mathrm{K}^{+}$ concentration inside the cell is larger than the $\mathrm{K}^{+}$ concentration outside the cell. Calculate the $\mathrm{K}^{+}$ ion concentration ratio necessary to produce a resting potential of $-70 . \mathrm{mV}$.
$$\frac{\left[\mathrm{K}^{+}\right]_{\text {inside }}}{\left[\mathrm{K}^{+}\right]_{\text {outside }}}=?$$

Key Concepts

Ionic Equilibrium

Ionic equilibrium is the state where the chemical driving force (due to the concentration gradient) and the electrical driving force (due to the voltage difference across the membrane) are balanced for an ion. This equilibrium is crucial for understanding how and why ions move across membranes and how the resting membrane potential is maintained.

Nernst Equation

The Nernst equation is a formula that calculates the equilibrium potential for a particular ion based on its concentration gradient across a membrane. This equation is fundamental in electrophysiology as it links the chemical gradient of ions to the electrical potential difference, providing insight into how ion distributions contribute to the overall membrane potential.

Resting Membrane Potential

The resting membrane potential is the difference in electric potential between the inside and the outside of a cell when it is not transmitting a signal. This potential is primarily established by differences in ion concentrations across the cell membrane and is essential for maintaining the cell's ability to generate and propagate electrical signals.

Concentration Gradient

A concentration gradient refers to the variation in the concentration of a specific substance, such as ions, between two regions. In biological systems, these gradients are vital for the diffusion of substances and they provide the driving force for many cellular processes, including the generation of electrical potentials.

Transcript

00:01 Okay, we want to answer this question, we have to talk about the resting membrane potential.

00:04 Remember that all our cells have a resting membrane potential, okay? all cells have a resting membrane potential.

00:16 However, some excitable cells can get out from this increasing memory potential and we can fire an action potential.

00:26 Okay, for example, in neurons or skeletal muscle.

00:29 So let's talk about the aggressive memory potential.

00:31 In cells, we're going to have a sodium potassium atp spam.

00:40 It is going to move three sodium ions out of the cell and two potassium ions inside the cells.

00:49 Okay, so as you're moving three sodium positively charged ions practically out of the cell, only putting inside two positively charged ions.

01:03 Then it means you are moving one extra positively charged ion out of the cell.

01:07 And this is going to make the extracellular electropositive and the intercellular electronegative.

01:14 This is going to contribute for the wasting memory potations.

01:17 However, there are also channels that are called potassium liquid channels.

01:30 Okay.

01:30 And they are going to move potassium ions down their concentration gradient.

01:35 Remember that potassium is higher.

01:38 In the intercellular and is lower in the extracellular...

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