Glossary of Terms
Schwann Cells - Non-nerve cells in the peripheral nervous system, similar to oligodendrocytes in the central nerve system, which wrap around axons to create a protective layer of myelin. They also may promote nerve regeneration following an injury.
Semaphorins - A family of proteins that play a role during axonal development. Semaphorins may inhibit axon growth or help growing axons find their way to their target connections – or both. These proteins act like traffic cops, telling growing axons where they can and cannot go so that they reach their destinations.
Serotonin - One of the groups of chemical messengers known as neurotransmitters that carries out communications in the brain and the body. This molecular messenger travels from neuron to neuron eliciting cellular responses that shape emotions and judgment.
Spasticity - An increase in muscle tone with exaggerated tendon reflexes.
Stem Cells - Self-renewing, primitive cells. When a stem cell divides, it creates another stem cell and a daughter cell that can become a mature cell in any organ in the body.
Sympathetic Nervous System - Controls involuntary functions of the body, such as heart rate and blood pressure.
Synapse - The connection between two neurons that enables them to communicate. Synapses enable nerve impulses to travel through chains of neurons.
Synaptic Adhesion Molecules (SAMs) - Molecules that establish the first contact between two neurons, holding the cell membranes in place while their connection, or synapse, forms.
Synaptogenesis - The process of forming a nerve-to-nerve junction or synapse. After the formation of the synapse is complete, the signal is relayed by the release of a chemical transmitter from one membrane that binds to a receptor in the second membrane
Courtesy Christopher Reeve Foundation