Neuron

The title of the Project: Membrane potential of a neuron

Purpose of the virtual laboratory work:

  • Investigate the fundamental principles of nerve cell membrane potential function.
  • Conduct virtual experiments to analyze the influence of various factors on membrane potential.
  • Draw conclusions about how membrane potential contributes to nerve impulse generation and transmission.

Theoretical part

Every living cell carries an electrical charge. This charge arises from the movement of charged particles called ions, flowing in and out of the cell. When at rest, the cell membrane holds a negative charge inside and a positive charge outside. This difference, known as the membrane potential (resting potential), typically measures around -70 mV in neurons.

When a neuron receives a nerve impulse, its membrane charge briefly changes. This shift, called the action potential, typically reaches around 110-120 mV in neurons.

Sources:

  1. The occurrence of nerve impulses and indicators of their conduction in various types of neurons. (2019). Biology. Textbook for 9th grade of secondary school.

Practical part

In this virtual simulation, you will control the process of a nerve impulse passing through a neuron.

Step 1. Familiarize yourself with the legend. The “Legend” section on the right side of the screen shows the symbols and their names like sodium and potassium ions, sodium and potassium gated channels and leak channels (Check out the glossary of terms below)

Step 2. In the “Show” section below, you can:

  • Show or hide: ions, membrane charge, ion concentration, and potential chart by checking or unchecking the boxes.

Step 3. The zoom slider is located on the left side of the screen. Use it to zoom in or out of the object.

Step 4. The current scene you are observing is the process occurring on the neuron membrane at rest. This means that most of the Na+ and K+ channels are gated. Pay attention to their concentration values and you will notice that:

  • The concentration of Na+ is much higher outside the cell than K+.
  • In the cytoplasm, the opposite is true: the concentration of K+ is much higher than Na+.
  • In addition, a negative charge (-) is stored inside the cell membrane, and a positive charge (+) outside.

Step 5. Observe the effect of a nerve impulse on the neuron membrane. Click the “Stimulate neuron” button.

Step 6. Analyze the changes. You may notice that the membrane charges have shifted. This means that the resting potential has shifted to the action potential. In real-time, this process happens very quickly.

  • Select “Slow motion” mode.
  • Click the “Stimulate neuron” button again.
  • Zoom in on the object using the zoom slider.

These actions will help you slow down the process and get a better look at it.

Step 7. Study the stages of action potential generation:

Depolarization:

  • Na+ channels open briefly.
  • Na+ diffuses into the cell.
  • The internal charge of the cell changes from negative (-) to positive (+).
  1. Repolarization:
  • The increased concentration of Na+ inside the cell causes the K+ channels to open.
  • K+ leaves the cell.
  • The internal charge of the cell returns to negative (-).
  1. Hyperpolarization:
  • Na+ channels close.
  • The membrane potential reaches a more negative value than at rest.
  1. Resting potential restoration:
  • K+ channels close slightly later than Na+ channels.
  • The cell gradually returns to its initial state.

All processes in our brain are based on this complex reaction.

Normally, millions of nerve impulses are transmitted from one neuron to another in the brain within milliseconds. This is how processes such as:

  • Brain activity
  • Muscle contraction
  • Increased heart rate and etc.

Step 8. To see the stages of the action potential passage in the form of a chart, check the box next to the Potential chart and click the Stimulate neuron button again.

Conclusion:

This simulation allowed students to visualize the complex processes occurring in a neuron and to understand how these processes are related to the transmission of information in the nervous system.

Terminology

Neuron-Нейрон-Жүйке жасушасы

Membrane potential-Мембранный потенциал-Мембраналық потенциал

Sodium ion-Ион натрия-Натрий ионы

Potassium ion-Ион калия-Калий ионы

Sodium gated channel-Закрытый натриевый канал-Жабық натрий каналы

Potassium gated channel-Закрытый калиевый канал-Жабық калий каналы

Sodium leak channel-Канал утечки натрия-Ашық натрий каналы

Potassium leak channel-Канал утечки калия-Ашық калий каналы

All ions-Все ионы-Барлық иондар

Charges-Заряды-Зарядтар

Concentrations-Концентрации-Концентрациялар

Potential chart-График потенциала-Потенциал графигі