Glial cells are the neurons' support crew: they provide structure and insulation, help with communication, and even take out the trash.
The myelin sheath insulates the axon like the coating on a wire, helping action potentials travel faster.
In multiple sclerosis the myelin sheath is damaged, so signals slow down or get disrupted even though the muscles themselves are fine.
All neurons fire the same basic way, but sensory neurons, interneurons, and motor neurons have different jobs.
In a reflex, sensory neurons carry information to the spinal cord, interneurons connect them to motor neurons, and motor neurons move the muscles, and this trio works together for almost everything.
Key terms
glial cells
Cells that support neurons by providing structure and insulation, helping with communication, and removing waste.
myelin sheath
An insulating layer formed by glial cells around the axon that helps action potentials travel faster.
multiple sclerosis (MS)
A disease in which the myelin sheath is damaged, slowing or disrupting signals and causing weakness, numbness, or blurry vision.
sensory neuron
A neuron that carries information from the senses, such as receptors in the skin, toward the central nervous system.
interneuron
A neuron within the central nervous system that communicates in between neurons, connecting sensory neurons to motor neurons.
motor neuron
A neuron that carries instructions from the central nervous system to the muscles, producing movement.
Watch out
Remember the direction: sensory neurons carry information in from the senses, interneurons work in between within the CNS, and motor neurons carry instructions out to muscles.