Neuroglia

Neural Stem Cells

Much like the bone cellsThe basic structural and functional units of life. and other collections of similar cells that we’ve seen, neuronsThe functional cells of the nervous system that transmit signals. arise from a neural stem cell. However, this neural stem cell does not only give rise to neurons. It also gives rise to cells called glial cells or neuroglia. These cells are like a support system for neurons. Are so specialized in carrying action potentials and electricity that they don’t like to do much of anything else. And it’s these neurological cells that modify the interstitial environment in the brain. Some of these neurological cells also make a substance called myelin which we’ll discuss later on.

Neuroglial cells make up just about 50% of all of your nervous tissue. The types of neuroglial cells found in the central nervous systemComposed of the brain and spinal cord; integrates and processes information.  differ from those found in the peripheral nervous systemPNS All nervous tissue outside the CNS; includes nerves and ganglia.. For example, the cells that produce myelin in your brain are distinct. They are different from the cells in the nerves of your hand.

CNS Neuroglia: Astrocytes

One of the main neuroglia cells that’s present in the brain are astrocytesStar-shaped glial cells in the CNS that support neurons and maintain the blood-brain barrier.. Astrocytes are very frequent among the nervous tissue. Their orientation in space creates the support framework for the brain. Your brain or anybody’s brain is actually about the consistency of tapioca. So it holds a shape but it’s definitely squishy. Astrocytes are like a server in a restaurant. Astrocytes take nutrients like oxygen and glucoseA simple sugar that is the main source of energy for cells. from a blood vessel. They feed them directly to the neuron. In doing so this prevents the neuron from being exposed to any chemicals or harmful substances in the blood vessel. Astrocytes can also function in Repairing damaged neurons. Current research on traumatic brain injuries is focused on these cells. Researchers assume that encouraging their repair activities could aid traumatic brain injury recovery.

CNS Neuroglia: Microglia

Also in your brain and spinal cordThe central nervous system structure that relays signals between the brain and body. there are these little tiny cells called microgliaSmall CNS glial cells that act as macrophages, cleaning up debris and pathogens.. They are like feather dusters for your central nervous systemThe organ system that controls body functions using electrical and chemical signals.. They basically roam around and clean things up. Technically, they belong to a category of cells called phagocytes. This is a word that just means a cell that eats. So microlia Rome the central nervous system cleaning up debris. It is thought that microglia play an enormous role in neural inflammation diseases. Deadening their activity can also reduce that damaging inflammation.

CNS Neuroglia: Oligodendrocytes

Oligodendrocytes are cells that make a lipid covering called myelin. It’s similar to the rubber covering on the outside of an electrical cord. This rubber prevents you from getting shocked if you touch the live wire underneath. Take a look at this Oligodendrocytes. It actually has some processes that reach out to two different neurons and interact with them. At the end of the little arms of the oligodendrocyte, you can see pillow-type structures. These structures are the myelin covering that wraps around this part of the neuron. It is this structure that gives them their name which literally means many branches.

CNS Neuroglia: Ependymal Cells

Many of us have heard about the procedure called a spinal tapA procedure to collect cerebrospinal fluid from the subarachnoid space.. There is spinal fluid that circulates between two layers of the coverings around your brain and spinal cord.  That fluid is different than your blood. Sometimes it needs to be sampled to rule out certain types of infection like meningitis. This fluid is called cerebrospinal fluid(CSF) – A fluid that cushions and nourishes the brain and spinal cord. or CSF. Whining all of the open spaces that contain cerebral spinal fluid are cells called ependymal cellsGlial cells that produce and circulate cerebrospinal fluid.. They have these little ciliaHair-like projections on the surface of some cells that move fluids or particles. on them. These little hairs all wave in unison. This action circulates the cerebrospinal fluid through these cavities. It moves up to your brain and flows back down your spineProminent ridge on the posterior scapula dividing it into supraspinous and infraspinous fossae.. These ependymal cells are crucial in making the cerebral spinal fluid. However, they do that at only very few places in the brain.

Neuroglia of the PNS

There are only two types of neuroglia worth mentioning here in this class. They are in the peripheral nervous system. All of the neuroglia we’ve spoken about before this slide is found only in the brain and spinal cord. These are part of the central nervous system. These two types of neuroglia here are only found in the peripheral nervous system. They are in the arms, legs, and body. Basically, they are found in anything that’s not the brain or the spinal cord. Satellite cells are very similar to astrocytes in that they adjust and regulate the interstitial fluids around a neuron. They wrap around the cell bodyThe central part of a neuron containing the nucleus and organelles. of neurons in somatic tissues. These cells form clusters of satellite cells and cell bodies called ganglia. Similar to Oligodendrocytes, there are cells called Schwan cells. Schwan cells make the myelin sheets for the neurons in the nerves of your peripheral nervous system.

The BBB

The blood brain barrier is a diffuse barrier it’s not like a membrane or a covering or anything like that. It’s really the collective activity of a lot of the neuroglia that are present in your brain and spinal cord. By by all working together they are capable of tightly controlling the interstitial environments for the neurons. Look at this picture more toward the left of this slide. Running down the middle of it, you can see a blood vessel. We certainly want to get the glucose and oxygen out of it. However, there may be other things in the blood vessel. I definitely don’t want to expose my brain neurons to these substances. First, there are cells called parasites wrapping around the blood vessel. Second, take a look at all of the green oligodendrocytesGlial cells in the CNS that form the myelin sheath around axons., which are pretty much epithelial cells. They are really big simple squamous epithelial cells. They form a diffuse barrier all over the blood vessel regulating what is allowed to leave. Second, observe all of the green astrocytes. They are all touching the blood vessel. Then they reach out to touch a neuron itself. They are also regulating the interstitial environment. This picture over on the right is a cross section A cut or slice of the body or an organ for study.. Working from the inside out, we have the endothelial cells. Then the parasite and the basement membrane follow. Lastly, we have the ends of the feet of the astrocytes.