Glia

Special cells live in your brain and spine.

These cells act like glue. They hold other cells in place. They also bring food and air to them.

Some cells make a coating. This coating helps signals move fast.

Other cells clean up. They destroy germs and bad things. They even help with how you breathe.

These cells are very important for your body. They help your brain stay healthy.

Your brain and spine are full of special cells called glia.

The word glia comes from a Greek word for glue. This is because these cells help hold the nervous system together. They do much more than just act like glue, though. Glia help keep your body in a healthy state. They also give nutrients and oxygen to your neurons.

There are many different types of glia. In your brain, astrocytes are very common. They link neurons to your blood supply. They also help form a barrier to protect the brain. Another type is called an oligodendrocyte. These cells make a coating called myelin. This coating works like insulation on a wire. It helps electrical signals move fast.

Other cells act like a cleanup crew. Microglia are small cells that move around the brain. They destroy germs and remove dead cells. In your nerves, Schwann cells also make myelin. They even help neurons grow back after an injury. Glia are very important for how you think and remember. They help your brain stay healthy every day.

Your brain and spinal cord are filled with amazing cells called glia.

They are also known as glial cells or neuroglia. These cells do not send electrical signals like neurons do. Instead, they make up more than half the volume of neural tissue in the human body. Glia are essential for keeping the nervous system healthy and working well. They help maintain a stable environment for your cells to live in. They also provide support and protection for the neurons in your body.

There are many ways these cells work to help you. Some glia act like a support system to hold neurons in place. Others act like a delivery service to supply nutrients and oxygen. Some glia provide insulation to keep one neuron from touching another. There are even cells that act like a cleanup crew to destroy germs and remove dead cells. Glia also help with breathing and how your brain sends messages. They can even play a part in how you form and keep memories.

Scientists first discovered these cells in 1856. A pathologist named Rudolf Virchow found them while looking for connective tissue in the brain. The name glia comes from the Greek words for "glue."

This name was used because they seemed to act like glue for the nervous system. For a long time, people thought glia were just passive bystanders. They believed glia just sat there while neurons did all the work. Now we know that glia are much more active and important than we once thought.

Different types of glia live in different places. In the central nervous system, astrocytes help link neurons to blood supplies.

Oligodendrocytes are another type that makes a coating called myelin. This myelin acts like insulation on a wire to help signals move fast. In the peripheral nervous system, Schwann cells do a similar job with myelin. Microglia are small cells that move around to protect the brain from damage. There are about 85 billion glial cells in the human brain. This is roughly the same number as the neurons in your brain.

Learning about glia helps us understand how our own bodies function. For example, the way astrocytes work is linked to blood flow in the brain. This is actually what doctors measure when they use an fMRI scan. We can also see how glia help the body heal after an injury. In your nerves, Schwann cells can actually help neurons grow back. In the brain, astrocytes might form a scar to protect an injured area. These cells are a vital part of every thought and movement you make.

Glia, also called glial cells or neuroglia, are non-neuronal cells within the nervous system. They are found in both the central nervous system (the brain and spinal cord) and the peripheral nervous system. Unlike neurons, glial cells do not produce electrical impulses. Despite this, they are vital to survival. They make up more than one half of the volume of neural tissue in the human body.

Glia maintain homeostasis, which is a stable internal environment. They also form myelin to insulate neurons and provide essential support and protection.

Glial cells perform several critical functions to keep the nervous system working. They provide structural support by holding neurons in place. They also act as a delivery system to supply nutrients and oxygen to neurons. To prevent interference, they insulate one neuron from another. Glia also serve as a cleanup crew to destroy pathogens and remove dead neurons. Beyond these roles, they influence neurotransmission and synaptic connections. They even play roles in physiological processes like breathing and the consolidation of memories.

In the central nervous system (CNS), there are several distinct types of glia. Astrocytes, or astroglia, have many projections that link neurons to blood supplies. They form the blood–brain barrier and regulate the chemical environment by removing excess potassium ions.

Oligodendrocytes are another CNS type. They wrap their cell membranes around axons to create a myelin sheath. This sheath provides insulation so electrical signals can travel more efficiently. Ependymal cells line the spinal cord and the brain's ventricular system. They secrete cerebrospinal fluid (CSF) and use cilia to help it circulate. Finally, microglia act as specialized macrophages. They use phagocytosis to protect the CNS by consuming harmful substances.

Radial glia are also found in the CNS, particularly during development. They act as a scaffold that helps newborn neurons migrate to their proper places. In the mature brain, certain radial glia remain, such as Bergmann glia in the cerebellum. In the peripheral nervous system (PNS), different cells take over specific roles. Schwann cells provide myelination for axons in the PNS, similar to oligodendrocytes. They also help clear debris to allow for neuron regrowth. Satellite cells surround neurons in ganglia to help regulate the external chemical environment. Enteric glial cells are also found in the digestive system to assist with homeostasis.

History shows how our understanding of these cells has changed. In 1856, the pathologist Rudolf Virchow discovered glia. He was searching for a "connective tissue" in the brain. The name comes from the Greek words "glia" or "gloia," meaning "glue."

This suggests that scientists originally thought they were just the glue of the nervous system. For a long time, glia were viewed as passive bystanders. Recent studies show they are much more active. They can respond to and manipulate neurotransmission in many ways.

Numerical data reveals the massive scale of these cells. There are approximately 85 billion glial cells in the human brain. This is roughly the same number as the neurons. However, the ratio of glia to neurons varies by location. In the cerebral cortex, the ratio is about 3.72. In the cerebellum, the ratio is much lower at only 0.23. In the basal ganglia and brainstem, the ratio is as high as 11.35. Within the brain, oligodendrocytes are the most frequent type, making up 45% to 75% of the glia. Astrocytes make up 19% to 40%, while microglia account for 10% or less.

Glial cells also behave differently during injury and repair. In the CNS, astrocytes can enlarge and proliferate to form a scar. This process, called gliosis, can actually inhibit the regrowth of damaged axons. In contrast, the PNS has a different approach. Schwann cells can regress to an earlier developmental state to encourage axon regrowth. This difference is why scientists hope for better spinal cord repairs in the future. Most glia come from ectodermal tissue, but microglia are an exception. They are derived from hematopoietic stem cells, which originate in the blood islands of the yolk sac during early development.