Introducing the spinal cord

The spinal cord is the delicate tissue encased in and protected by the hard vertebrae of the spinal column. Together the brain and spinal cord form the bodys central nervous system.

The spinal cord is made up of millions of nerve cells that carry signals to and from the brain and out into other parts of the body. The information that allows us to sit, run, go to the toilet and breathe travels along the spinal cord.

The main cell type found in the spinal cord, the neuron, conveys information up and down the spinal cord in the form of electrical signals. An axon(also known as a nerve fibre) is a long, slender projection of a neuron that conducts these signals away from the neuron's cell body. Each neuron has only one axon, and it can be as long as the entire spinal cord, up to 45cm in an adult human.

The axons that carry messages down the spinal cord (from the brain) are called motor axons. They control the muscles of internal organs (such as heart, stomach, intestines) and those of the legs and arms. They also help regulate blood pressure, body temperature, and the bodys response to stress.

The axons that travel up the cord (to the brain) carry sensory information from the skin, joints and muscles (touch, pain, temperature) and from internal organs (such as heart and lungs). These are the sensory axons.

Neurons in the spinal cord also need the support of other cell types. The oligodendrocyte, for example, forms structures that wrap around and insulate the axon. Called myelin, this insulating material helps the electrical impulse to flow quickly and efficiently down the axon.

A spinal cord injury affects both neurons and the myelin sheath that insulates axonsWhen the spinal cord is injured, the initial trauma causes cell damage and destruction, and triggers a cascade of eventsthat spread around the injury site affecting a number of different types of cells. Axons are crushed and torn, and oligodendrocytes, the nerve cells that make up the insulating myelin sheath around axons, begin to die. Exposed axons degenerate, the connection between neurons is disrupted and the flow of information between the brain and the spinal cord is blocked.

The spine has different sections. The level of paralysis depends on the location of the injury.

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Spinal cord injuries: how could stem cells help? | Europe ...