The way action potentials move along axons is a fascinating process. It helps our nervous system communicate quickly. Let’s break it down in simpler terms.
First, a neuron starts at what we call its resting membrane potential. This is usually about -70 mV.
The resting potential is maintained by a special pump that moves sodium ions out of the cell while bringing potassium ions in. It pushes 3 sodium ions out for every 2 potassium ions it brings in. This creates a difference in the concentration of these ions inside and outside the neuron.
When something exciting happens, like when neurotransmitters or sensory signals stimulate the neuron, the process begins.
Voltage-gated sodium channels open up and sodium ions rush inside the neuron. This influx of positive ions changes the charge inside the neuron, making it less negative, or depolarizing it. If the charge reaches around -55 mV, the neuron generates an action potential.
Once an action potential starts at the axon hillock, it travels along the axon through two main ways:
When sodium flows into the neuron, it causes nearby areas of the axon to depolarize too. This change triggers the opening of neighboring sodium channels, creating a wave-like movement of the action potential. You can think of it like knocking over a line of dominoes!
In myelinated axons, the action potentials jump from one gap, called a node of Ranvier, to another. This jumping makes the signal travel much faster because the action potential skips over the insulated parts of the axon. Imagine a rabbit hopping from rock to rock in a stream, avoiding the water in between!
After an action potential passes by, the neuron goes through a period called the refractory period. This time is necessary because it stops the neuron from sending another signal too quickly.
During the absolute refractory period, no new action potentials can be triggered because the sodium channels can’t be used right away. During the relative refractory period, it is a bit harder but still possible to start a new action potential, especially if the neuron is more negatively charged than usual.
The speed of action potentials can be affected by a few things:
In short, action potentials travel along axons by coordinating the movement of ions and the activities of channels in the neuron. This is a key part of how our nervous system communicates effectively.
The way action potentials move along axons is a fascinating process. It helps our nervous system communicate quickly. Let’s break it down in simpler terms.
First, a neuron starts at what we call its resting membrane potential. This is usually about -70 mV.
The resting potential is maintained by a special pump that moves sodium ions out of the cell while bringing potassium ions in. It pushes 3 sodium ions out for every 2 potassium ions it brings in. This creates a difference in the concentration of these ions inside and outside the neuron.
When something exciting happens, like when neurotransmitters or sensory signals stimulate the neuron, the process begins.
Voltage-gated sodium channels open up and sodium ions rush inside the neuron. This influx of positive ions changes the charge inside the neuron, making it less negative, or depolarizing it. If the charge reaches around -55 mV, the neuron generates an action potential.
Once an action potential starts at the axon hillock, it travels along the axon through two main ways:
When sodium flows into the neuron, it causes nearby areas of the axon to depolarize too. This change triggers the opening of neighboring sodium channels, creating a wave-like movement of the action potential. You can think of it like knocking over a line of dominoes!
In myelinated axons, the action potentials jump from one gap, called a node of Ranvier, to another. This jumping makes the signal travel much faster because the action potential skips over the insulated parts of the axon. Imagine a rabbit hopping from rock to rock in a stream, avoiding the water in between!
After an action potential passes by, the neuron goes through a period called the refractory period. This time is necessary because it stops the neuron from sending another signal too quickly.
During the absolute refractory period, no new action potentials can be triggered because the sodium channels can’t be used right away. During the relative refractory period, it is a bit harder but still possible to start a new action potential, especially if the neuron is more negatively charged than usual.
The speed of action potentials can be affected by a few things:
In short, action potentials travel along axons by coordinating the movement of ions and the activities of channels in the neuron. This is a key part of how our nervous system communicates effectively.