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Nervous System

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About

The nervous system coordinates actions and transmits signals between different parts of the body. Neurons communicate through electrical impulses called action potentials. This simulation shows how signals propagate along an axon, the role of myelin in speeding transmission, and how synapses pass signals to other cells.

Key Concepts

Action Potential

A rapid change in membrane potential from -70mV (resting) to +40mV (peak) and back. This electrical signal travels along the axon.

Myelin Sheath

Fatty insulation around axons that dramatically increases signal speed through saltatory conduction - signals "jump" between nodes of Ranvier.

Synapse

Junction between neurons where electrical signals convert to chemical signals (neurotransmitters) to communicate with the next cell.

Resting Potential

The baseline electrical state of a neuron at -70mV, maintained by ion pumps and selective membrane permeability.

How Neurons Fire

1. Depolarization

Stimulus opens Na+ channels, sodium rushes in, voltage becomes more positive.

2. Repolarization

K+ channels open, potassium flows out, voltage becomes negative again.

3. Hyperpolarization

Voltage briefly drops below resting potential before recovering.

How to Use

  • Adjust stimulus intensity to see firing frequency change
  • Toggle myelin to compare signal speeds with and without insulation
  • Watch action potentials travel from cell body to synapse

Applications

Neurology

Diagnosing and treating conditions like multiple sclerosis (myelin damage).

Anesthesiology

Nerve blocks work by preventing action potential propagation.

Brain-Computer Interfaces

Interpreting neural signals to control prosthetic devices.

Mental Health

Many medications work by altering neurotransmitter function at synapses.