Neuron Resting Potential

Summary

The video explains how neurons maintain a resting potential, an electrical difference across their cell membranes, usually between -40 to -90 millivolts. It describes how potassium ions diffuse out of the neuron, leaving the inside more negative, creating this resting state. When a neuron is stimulated and the negative potential becomes less negative, an action potential is triggered, making the inside of the neuron briefly positive. These action potentials, rather than resting potentials, are what transmit information throughout the nervous system.

Takeaways

• 🧠 Unstimulated neurons maintain a constant electrical difference, known as resting potential, across their cell membranes.
• ⚡ The resting potential is always negative inside the cell, typically ranging from -40 to -90 millivolts.
• 🔋 When a neuron is stimulated, the internal potential can become more or less negative, depending on the stimulus.
• 🚀 If the potential becomes less negative and reaches a certain level, called the threshold, an action potential is triggered.
• 🔄 During an action potential, the neuron briefly becomes positive inside, reaching between 20 to 50 millivolts.
• ⏳ Action potentials last only a few milliseconds before the neuron restores its negative resting potential.
• 🧬 The neuron's cell membrane contains channel proteins that control ion movement, crucial for maintaining potentials.
• 🧪 Potassium ions mainly reside inside the cell, while sodium ions are found in the extracellular fluid outside the cell.
• 🛑 In an unstimulated neuron, only potassium channels are open, allowing potassium ions to diffuse out of the cell.
• ⚖️ The resting potential is achieved when the diffusion of potassium ions out of the neuron is balanced by an opposing electrical force.

Q & A

What is the resting potential of an unstimulated neuron?

The resting potential of an unstimulated neuron is a constant electrical difference across the cell membrane, which is always negative inside the cell and ranges from -40 to -90 millivolts.

What happens when a neuron is stimulated?

When a neuron is stimulated, the negative potential inside the neuron can become either more or less negative. If it becomes sufficiently less negative and reaches a level called the threshold, an action potential is triggered.

What is an action potential, and how long does it last?

An action potential is a rapid change in the neuron's electrical potential, where the inside of the neuron becomes positive, ranging from +20 to +50 millivolts. It lasts for a few milliseconds before the cell restores its negative resting potential.

What ions are found inside and outside the neuron?

Inside the neuron, there are mainly positively charged potassium ions and large negatively charged organic molecules, such as proteins. Outside the neuron, in the extracellular fluid, there are mostly positively charged sodium ions and negatively charged chloride ions.

How do ions travel across the neuron's cell membrane?

Ions travel through channel proteins that extend across the neuron's cell membrane because charged particles cannot pass through the lipid bilayer of the membrane on their own.

Which ion channels are open in an unstimulated neuron?

In an unstimulated neuron, only potassium channels are open, allowing potassium ions to cross the membrane. Sodium channels remain closed in this state.

Why does the inside of the neuron become negative during resting potential?

The inside of the neuron becomes negative because potassium ions diffuse out of the cell, leaving behind large negatively charged organic ions. As more potassium ions leave, the inside becomes increasingly negative.

What causes potassium ions to be pulled back into the neuron during resting potential?

As potassium ions diffuse out, an electrical force develops due to the attraction of opposite charges. This electrical force tends to pull potassium ions back into the neuron.

What is the significance of the balance between potassium ion diffusion and electrical attraction?

The balance between potassium ion diffusion out of the cell (due to concentration differences) and the electrical attraction pulling them back inside creates the resting potential of the neuron.

How many potassium ions need to leave the neuron to create a resting potential of -60 millivolts?

Only about 1/10,000 of the potassium ions initially inside the neuron need to leave in order to create a resting potential of -60 millivolts.

What is the primary difference between resting potential and action potential in terms of information transmission?

While resting potential helps maintain the neuron's stable electrical state, it is the action potentials that carry information through the nervous system.