How Does Your Nervous System Work?

Neuroglia Cells (or Glial Cells):

5 to 50 times more numerous than neurons. They constitute 80-98% of nervous tissue in the body and nearly ½ of neural tissue volume in the central nervous system. Dysfunction or deteriorization of these cells causes Luogh Gehrig’s disease. These cells divide mitotically (make more copies of themselves) throughout life, unlike neurons. Most brain tumors are cancers of these types of cells (gliomas), this is because typically gliomas reproduce themselves and divide but neurons typically do not divide after birth. Within the central nervous system there are four types of neuroglial cells: astrocytes, ependymal cells, microglia and oligodendrocytes.

Astrocytes are important because they tie capillaries to the neurons. This is important for us because our nervous tissue does not store oxygen but always needs glucose and oxygen in order to function, and the astrocytes ensure this. They also form the blood-brain barrier, which is a protective barrier or mechanism that helps maintain a stable environmental for the neurons of the brain. These cells are also antigen-presenting cells. The ependymal cells line the cavities of our brain and spinal cord. They are important because they produce and circulate the fluid that surrounds the brain and spinal cord. Many of them have cilia (little tail-like appendices that wiggle). Microglial cells are macrophages, which means they are in charge of getting rid of waste like invading bacteria and dead cells. The oligodendecytes act like

In the Peripheral nervous system has two other types of glial cells: the satellite cells, which cover the head of the neurons and Schwann cells that forms myolin sheaths around the extensions of nerve cells. The Schwann cells are also phagasitic, which means they also “eat” waste and move it out of the area.

Neurons

The message transporting cells of our nervous system. These are important because they transmit the impulses that allow us to since, think and respond to the world around us. The neuron has three main parts, these are the dendrites, cell body and the axon. The axon is the long extension that carries the signal to other nervous cells. The dendrites are extensions off of the cell body that can look like hair or tee limbs. These can either be stimulated by external stimuli or by the axons of other nerve cells. The cell body is the large usually central part that keeps the cell alive.

Some Vocabulary

Axon: the “wire” that connects the neurons and allows them to send a message back and forth.

Dendrite: the hair-like extensions off a nerve cell body that transmit signals.

Grey matter: Tissue formed by neuron cell bodies and unmyelinated (un-insulated, without a fatty wrapping) nerve fibers. The gray color comes from the color of the actual nerve cells.

White matter: Tissue formed from myelinated nerve fibers (axons). The white color comes from the color of the fatty myelin sheath.

A group or cluster of nerve cell bodies in the central nervous system is called a nucleus. (these are similar to a hub in air travel.)

A group or cluster of nerve cell bodies in the peripheral nervous system is called a ganglion. (similar to the nuclei, but out side the brain/ spinal cord)

A bundle of nerve processes or fibers (axons) in the central nervous system is called a tract.

A bundle of nerve processes or fibers (axons) in the peripheral nervous system is called a nerve.