4.2: Neurons and Glial Cells (2023)

Skills to Develop

  • List and describe the functions of the structural components of a neuron
  • List and describe the four main types of neurons
  • Compare the functions of different types of glial cells

Nervous systems throughout the animal kingdom vary in structure and complexity, as illustrated by the variety of animals shown in Figure \(\PageIndex{1}\). Some organisms, like sea sponges, lack a true nervous system. Others, like jellyfish, lack a true brain and instead have a system of separate but connected nerve cells (neurons) called a “nerve net.” Echinoderms such as sea stars have nerve cells that are bundled into fibers called nerves. Flatworms of the phylum Platyhelminthes have both a central nervous system (CNS), made up of a small “brain” and two nerve cords, and a peripheral nervous system (PNS) containing a system of nerves that extend throughout the body. The insect nervous system is more complex but also fairly decentralized. It contains a brain, ventral nerve cord, and ganglia (clusters of connected neurons). These ganglia can control movements and behaviors without input from the brain. Octopi may have the most complicated of invertebrate nervous systems—they have neurons that are organized in specialized lobes and eyes that are structurally similar to vertebrate species.

4.2: Neurons and Glial Cells (1)

Compared to invertebrates, vertebrate nervous systems are more complex, centralized, and specialized. While there is great diversity among different vertebrate nervous systems, they all share a basic structure: a CNS that contains a brain and spinal cord and a PNS made up of peripheral sensory and motor nerves. One interesting difference between the nervous systems of invertebrates and vertebrates is that the nerve cords of many invertebrates are located ventrally whereas the vertebrate spinal cords are located dorsally. There is debate among evolutionary biologists as to whether these different nervous system plans evolved separately or whether the invertebrate body plan arrangement somehow “flipped” during the evolution of vertebrates.

Link to Learning

(Video) The Neuron - Structure and Function - Neuroscience - Lesson 4.2

Watch this video of biologist Mark Kirschner discussing the “flipping” phenomenon of vertebrate evolution.

The nervous system is made up of neurons, specialized cells that can receive and transmit chemical or electrical signals, and glia, cells that provide support functions for the neurons by playing an information processing role that is complementary to neurons. A neuron can be compared to an electrical wire—it transmits a signal from one place to another. Glia can be compared to the workers at the electric company who make sure wires go to the right places, maintain the wires, and take down wires that are broken. Although glia have been compared to workers, recent evidence suggests that also usurp some of the signaling functions of neurons.

There is great diversity in the types of neurons and glia that are present in different parts of the nervous system. There are four major types of neurons, and they share several important cellular components.

Neurons

The nervous system of the common laboratory fly, Drosophila melanogaster, contains around 100,000 neurons, the same number as a lobster. This number compares to 75 million in the mouse and 300 million in the octopus. A human brain contains around 86 billion neurons. Despite these very different numbers, the nervous systems of these animals control many of the same behaviors—from basic reflexes to more complicated behaviors like finding food and courting mates. The ability of neurons to communicate with each other as well as with other types of cells underlies all of these behaviors.

Most neurons share the same cellular components. But neurons are also highly specialized—different types of neurons have different sizes and shapes that relate to their functional roles.

Parts of a Neuron

Like other cells, each neuron has a cell body (or soma) that contains a nucleus, smooth and rough endoplasmic reticulum, Golgi apparatus, mitochondria, and other cellular components. Neurons also contain unique structures, illustrated in Figure \(\PageIndex{2}\) for receiving and sending the electrical signals that make neuronal communication possible. Dendrites are tree-like structures that extend away from the cell body to receive messages from other neurons at specialized junctions called synapses. Although some neurons do not have any dendrites, some types of neurons have multiple dendrites. Dendrites can have small protrusions called dendritic spines, which further increase surface area for possible synaptic connections.

Once a signal is received by the dendrite, it then travels passively to the cell body. The cell body contains a specialized structure, the axon hillock that integrates signals from multiple synapses and serves as a junction between the cell body and an axon. An axon is a tube-like structure that propagates the integrated signal to specialized endings called axon terminals. These terminals in turn synapse on other neurons, muscle, or target organs. Chemicals released at axon terminals allow signals to be communicated to these other cells. Neurons usually have one or two axons, but some neurons, like amacrine cells in the retina, do not contain any axons. Some axons are covered with myelin, which acts as an insulator to minimize dissipation of the electrical signal as it travels down the axon, greatly increasing the speed on conduction. This insulation is important as the axon from a human motor neuron can be as long as a meter—from the base of the spine to the toes. The myelin sheath is not actually part of the neuron. Myelin is produced by glial cells. Along the axon there are periodic gaps in the myelin sheath. These gaps are called nodes of Ranvier and are sites where the signal is “recharged” as it travels along the axon.

It is important to note that a single neuron does not act alone—neuronal communication depends on the connections that neurons make with one another (as well as with other cells, like muscle cells). Dendrites from a single neuron may receive synaptic contact from many other neurons. For example, dendrites from a Purkinje cell in the cerebellum are thought to receive contact from as many as 200,000 other neurons.

(Video) Neuroglial Cell Types by location and Basic function|| 6 Types of Glial cells and their function

Art Connection

4.2: Neurons and Glial Cells (2)

Which of the following statements is false?

  1. The soma is the cell body of a nerve cell.
  2. Myelin sheath provides an insulating layer to the dendrites.
  3. Axons carry the signal from the soma to the target.
  4. Dendrites carry the signal to the soma.

Types of Neurons

There are different types of neurons, and the functional role of a given neuron is intimately dependent on its structure. There is an amazing diversity of neuron shapes and sizes found in different parts of the nervous system (and across species), as illustrated by the neurons shown in Figure \(\PageIndex{3}\).

4.2: Neurons and Glial Cells (3)

While there are many defined neuron cell subtypes, neurons are broadly divided into four basic types: unipolar, bipolar, multipolar, and pseudounipolar. Figure \(\PageIndex{4}\) illustrates these four basic neuron types. Unipolar neurons have only one structure that extends away from the soma. These neurons are not found in vertebrates but are found in insects where they stimulate muscles or glands. A bipolar neuron has one axon and one dendrite extending from the soma. An example of a bipolar neuron is a retinal bipolar cell, which receives signals from photoreceptor cells that are sensitive to light and transmits these signals to ganglion cells that carry the signal to the brain. Multipolar neurons are the most common type of neuron. Each multipolar neuron contains one axon and multiple dendrites. Multipolar neurons can be found in the central nervous system (brain and spinal cord). An example of a multipolar neuron is a Purkinje cell in the cerebellum, which has many branching dendrites but only one axon. Pseudounipolar cells share characteristics with both unipolar and bipolar cells. A pseudounipolar cell has a single process that extends from the soma, like a unipolar cell, but this process later branches into two distinct structures, like a bipolar cell. Most sensory neurons are pseudounipolar and have an axon that branches into two extensions: one connected to dendrites that receive sensory information and another that transmits this information to the spinal cord.

4.2: Neurons and Glial Cells (4)

Everyday Connection: Neurogenesis

At one time, scientists believed that people were born with all the neurons they would ever have. Research performed during the last few decades indicates that neurogenesis, the birth of new neurons, continues into adulthood. Neurogenesis was first discovered in songbirds that produce new neurons while learning songs. For mammals, new neurons also play an important role in learning: about 1000 new neurons develop in the hippocampus (a brain structure involved in learning and memory) each day. While most of the new neurons will die, researchers found that an increase in the number of surviving new neurons in the hippocampus correlated with how well rats learned a new task. Interestingly, both exercise and some antidepressant medications also promote neurogenesis in the hippocampus. Stress has the opposite effect. While neurogenesis is quite limited compared to regeneration in other tissues, research in this area may lead to new treatments for disorders such as Alzheimer’s, stroke, and epilepsy.

(Video) Staining neurons

How do scientists identify new neurons? A researcher can inject a compound called bromodeoxyuridine (BrdU) into the brain of an animal. While all cells will be exposed to BrdU, BrdU will only be incorporated into the DNA of newly generated cells that are in S phase. A technique called immunohistochemistry can be used to attach a fluorescent label to the incorporated BrdU, and a researcher can use fluorescent microscopy to visualize the presence of BrdU, and thus new neurons, in brain tissue. Figure \(\PageIndex{5}\) is a micrograph which shows fluorescently labeled neurons in the hippocampus of a rat.

4.2: Neurons and Glial Cells (5)

Link to Learning

This site contains more information about neurogenesis, including an interactive laboratory simulation and a video that explains how BrdU labels new cells.

Glia

While glia are often thought of as the supporting cast of the nervous system, the number of glial cells in the brain actually outnumbers the number of neurons by a factor of ten. Neurons would be unable to function without the vital roles that are fulfilled by these glial cells. Glia guide developing neurons to their destinations, buffer ions and chemicals that would otherwise harm neurons, and provide myelin sheaths around axons. Scientists have recently discovered that they also play a role in responding to nerve activity and modulating communication between nerve cells. When glia do not function properly, the result can be disastrous—most brain tumors are caused by mutations in glia.

Types of Glia

There are several different types of glia with different functions, two of which are shown in Figure \(\PageIndex{6}\). Astrocytes, shown in Figure \(\PageIndex{7}\) make contact with both capillaries and neurons in the CNS. They provide nutrients and other substances to neurons, regulate the concentrations of ions and chemicals in the extracellular fluid, and provide structural support for synapses. Astrocytes also form the blood-brain barrier—a structure that blocks entrance of toxic substances into the brain. Astrocytes, in particular, have been shown through calcium imaging experiments to become active in response to nerve activity, transmit calcium waves between astrocytes, and modulate the activity of surrounding synapses.

4.2: Neurons and Glial Cells (6)

Satellite glia provide nutrients and structural support for neurons in the PNS. Microglia scavenge and degrade dead cells and protect the brain from invading microorganisms. Oligodendrocytes, shown in Figure \(\PageIndex{7}\) form myelin sheaths around axons in the CNS. One axon can be myelinated by several oligodendrocytes, and one oligodendrocyte can provide myelin for multiple neurons. This is distinctive from the PNS where a single Schwann cell provides myelin for only one axon as the entire Schwann cell surrounds the axon. Radial glia serve as scaffolds for developing neurons as they migrate to their end destinations. Ependymal cells line fluid-filled ventricles of the brain and the central canal of the spinal cord. They are involved in the production of cerebrospinal fluid, which serves as a cushion for the brain, moves the fluid between the spinal cord and the brain, and is a component for the choroid plexus.

(Video) 4.2 Part 2 Glia

4.2: Neurons and Glial Cells (7)

Summary

The nervous system is made up of neurons and glia. Neurons are specialized cells that are capable of sending electrical as well as chemical signals. Most neurons contain dendrites, which receive these signals, and axons that send signals to other neurons or tissues. There are four main types of neurons: unipolar, bipolar, multipolar, and pseudounipolar neurons. Glia are non-neuronal cells in the nervous system that support neuronal development and signaling. There are several types of glia that serve different functions.

Art Connections

Figure \(\PageIndex{2}\): Which of the following statements is false?

  1. The soma is the cell body of a nerve cell.
  2. Myelin sheath provides an insulating layer to the dendrites.
  3. Axons carry the signal from the soma to the target.
  4. Dendrites carry the signal to the soma.
Answer

B

Glossary

astrocyte
glial cell in the central nervous system that provide nutrients, extracellular buffering, and structural support for neurons; also makes up the blood-brain barrier
axon
tube-like structure that propagates a signal from a neuron’s cell body to axon terminals
axon hillock
electrically sensitive structure on the cell body of a neuron that integrates signals from multiple neuronal connections
axon terminal
structure on the end of an axon that can form a synapse with another neuron
dendrite
structure that extends away from the cell body to receive messages from other neurons
ependymal
cell that lines fluid-filled ventricles of the brain and the central canal of the spinal cord; involved in production of cerebrospinal fluid
glia
(also, glial cells) cells that provide support functions for neurons
microglia
glia that scavenge and degrade dead cells and protect the brain from invading microorganisms
myelin
fatty substance produced by glia that insulates axons
neuron
specialized cell that can receive and transmit electrical and chemical signals
nodes of Ranvier
gaps in the myelin sheath where the signal is recharged
oligodendrocyte
glial cell that myelinates central nervous system neuron axons
radial glia
glia that serve as scaffolds for developing neurons as they migrate to their final destinations
satellite glia
glial cell that provides nutrients and structural support for neurons in the peripheral nervous system
Schwann cell
glial cell that creates myelin sheath around a peripheral nervous system neuron axon
synapse
junction between two neurons where neuronal signals are communicated

FAQs

4.2: Neurons and Glial Cells? ›

The nervous system is made up of neurons, specialized cells that can receive and transmit chemical or electrical signals, and glia, cells that provide support functions for the neurons by playing an information processing role that is complementary to neurons.

What is the ratio of neurons to glial cells? ›

60.84 billion cells in the cerebral cortex are glia, while only 16.34 billion cells are neurons, giving this large region a glia to neuron ratio of about 3.76 to 1. It's the inverse in the cerebellum, an evolutionarily ancient part of the brain that sits astride the brain stem.

Are 10% neurons and 90% glial cells? ›

Another mystery hidden within our crinkled cortices is that out of all the brain's cells, only 10 percent are neurons; the other 90 percent are glial cells, which encapsulate and support neurons, but whose function remains largely unknown.

What are the 4 main types of glial cells which support the neurons? ›

Glial cells support neurons and maintain their environment. Glial cells of the (a) central nervous system include oligodendrocytes, astrocytes, ependymal cells, and microglial cells.

What do glial cells 4 do? ›

Functions include: clean up brain "debris"; transport nutrients to neurons; hold neurons in place; digest parts of dead neurons; regulate content of extracellular space; promote synaptic connections; clear excess neurotransmitters; ensure the continued function of neurons.

Do you have more neurons or glial cells? ›

Glial cells are far more numerous than neurons and, unlike neurons, are capable of mitosis. For more information about anatomy of brain and CNS, go to the Nervous System section of the Anatomy & Physiology module on this Website.

Do we have more neurons than glial cells? ›

Glia are more numerous than nerve cells in the brain, outnumbering them by a ratio of perhaps 3 to 1. Although glial cells also have complex processes extending from their cell bodies, they are generally smaller than neurons, and they lack axons and dendrites (Figure 1.4).

What are 90% of neurons in a nervous? ›

More than 90 percent of the neurons of the body are association neurons.

What is the ratio of neurons to astrocytes? ›

Interestingly, in P3-4 cultures treated with AraC (4–10 μM) the neuron to glia ratio was roughly 1.4 ± 0.1 neuron per astrocyte whereas cultures treated with low concentrations of FUdR showed a significantly higher neuron to astrocyte ratio of about 5.9 ± 0.8neurons per astrocyte (p < 0.001).

Are microglia 10% of brain cells? ›

Microglial cells are the most prominent immune cells of the central nervous system (CNS) and are the first to respond when something goes wrong in the brain [1]. The microglial population accounts for approximately 10% of the cells in the whole brain [2].

How do you keep glial cells healthy? ›

In addition to eating berries, consuming ginger, green tea and oily fish may help protect the brain from neuro-degeneration. These foods may protect glial cells, which help to remove toxins from the brain. By doing this, the glial cells play a role in reducing the risk of Alzheimer's or other dementia diseases.

How do you increase glial cells in the brain? ›

Factors that encourage neurogenesis include:
  1. Learning new skills.
  2. Exercise.
  3. Sex.
  4. Intermittent fasting.
  5. Calorie restriction.
  6. Caffeine.
  7. Resveratrol (found in red wine)
  8. Curcumin (found in turmeric)
May 23, 2021

What happens when glial cells are damaged? ›

In addition to activation on nervous system injury and during neuronal degeneration, glial cells also degenerate in several neurodegenerative diseases. Therefore, glial cell loss may contribute to the impairment of learning and memory.

Why are glial cells so important? ›

Glial cells help support, connect, and protect the neurons of the central and peripheral nervous systems. They come in many shapes, sizes, and types, each performing specialized functions. In the CNS, glial cells regulate neurotransmission and help form the blood-brain barrier.

Can we live without glial cells? ›

Studies have shown that without glial cells, neurons and their synapses fail to function properly.

Which glial cell is most important? ›

Oligodendrocytes. Oligodendrocytes come from neural stem cells. The word is made up of a few Greek terms that mean "cells with several branches." The main purpose of oligodendrocytes is to help information move faster along axons in the brain.

Which brain has the most neurons? ›

The largest number of cortical neurons in non-primate mammals is found in the false killer whale with 10 500 million and the African elephant with 11 000 million, which is less than the number found in humans, despite the much larger brains of the former two.

Why do neurons need more energy than glial cells? ›

Brain cells are divided into nerve cells and glial cells, of which there are distinct types and many different ”task bearer”. Neurons consume a considerably higher amount of energy than glial cells because functional tasks of synapses, the chemical-electric links between neurons consume a lot of energy.

What are the 4 main types of cells in the brain? ›

  • Neurons. The numbers of neurons varies extremly between species: the common fruit fly has about 100.000 neurons, whereas it is estimated that the human brain has about 1014 (100 billion) neurons. ...
  • Glia Cell Types. Summary. ...
  • Astrocytes. ...
  • Oligodendrocytes. ...
  • Microglia.

What is the difference between a neuron and a glia? ›

Neurons generate and propagate electrical and chemical signals, whereas glia function mainly to modulate neuron function and signaling. Just as there are many different kinds of neurons with different roles, there are also many types of glia that perform diverse functions.

Do glial cells replace neurons? ›

Furthermore, various types of glial progenitors have the potential to generate neurons under pathological conditions. Thus, glial responses to injury and disease serves two main purposes: 1) repair and preservation of existing cell populations, and 2) regeneration of lost populations, including both neurons and glia.

What percent of brain is neurons? ›

Generic rodent brainHuman brain
Neurons, cerebral cortex2 billion16 billion
Relative size of the cerebral cortex77% of brain mass82% of brain mass
Relative number of neurons in cerebral cortex17% of brain neurons19% of brain neurons
Mass, cerebellum133 g154 g
6 more rows

What type are 99% of all neurons? ›

Interneurons make up > 99% of all the neurons in the body. The primary function of interneurons is integration. They carry sensory information and regulate motor activity.

Where are 80% of neurons located? ›

Those neurons, known as granule cells, account for 80 percent of the neurons in the brain – all packed into the cerebellum – but only about 10 percent of its volume.

Do you have 10 billion neurons in your brain? ›

Human Brain as a Scaled-Up Primate Brain

Remarkably, at an average of 86 billion neurons and 85 billion nonneuronal cells (25), the human brain has just as many neurons as would be expected of a generic primate brain of its size and the same overall 1:1 nonneuronal/neuronal ratio as other primates (26).

How much of brain is glial cells? ›

Ben Barres' research has led to a greater appreciation of glial cells, which comprise 90 percent of the brain.

What part of the brain has the highest ratio of neurons to glia? ›

Our results showed that area 9L of the human prefrontal cortex has higher glial density than expected for neuron density based on allometric scaling in nonhuman anthropoids, a finding that is consistent when both species mean data (46% more glia per neuron) and independent contrasts (32% more glia per neuron) are used.

What makes up 80 of our brain volume? ›

The preponderance of the cerebral cortex (which, with its supporting structures, makes up approximately 80 percent of the brain's total volume) is actually a recent development in the course of evolution.

How can I improve my brain microglia? ›

Maintain a healthy diet: Compounds found in fruits, vegetables, and healthy fats, can keep your microglia young, and shift them towards an anti-inflammatory form. Keep your gut bacteria happy: The brain and the gut are connected by the vagus nerve, so microbes living in our gut have a large effect on the brain.

What does microglia eat up? ›

Microglia have a general garbage-disposal role in the brain, eating any rubbish accumulating in the extracellular space, including protein aggregates and cellular debris.

How do you deactivate microglia? ›

Etanercept – Etanercept is able to block the production of a pro-inflammatory cytokine released by activated microglia in the brain. Nancy Klimas is using it to tamp down neuroinflammation in clinical trials for GWI and ME/CFS. Ceftriaxone is one of two antibiotics that may be able to inhibit glial cell activity.

What diseases are caused by glial cells? ›

Recent advances have demonstrated that glial cells, specifically microglia and astroglia, are involved in several neurodegenerative diseases including Amyotrophic lateral sclerosis (ALS), Epilepsy, Parkinson's disease (PD), Alzheimer's disease (AD), and frontotemporal dementia (FTD).

What diseases affect glial cells? ›

Dysfunction in glial cells associates with a variety of brain diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, glioblastoma, autism and psychiatric disorders.

What supplements help glial cells? ›

G-5 Supplement is a chemically defined, serum-free supplement based on Bottenstein's G-5 formulation. It is recommended for growth and expression of glial cells (normal and tumor) of astrocytic phenotype (astrocytes).

How can I increase my brain glial cells naturally? ›

In addition to building fitness, regular endurance exercises like running, swimming, or biking can preserve existing brain cells. They can also encourage new brain cell growth. Not only is exercise good for your body, it can also help improve memory, increase focus, and sharpen your mind.

Do glial cells increase intelligence? ›

Neuroscientists have discovered that these cells are essential for brain development, proper metabolic brain function, neuronal health, and now, perhaps, for intelligence itself.

Does exercise increase glial activation in the brain? ›

Physical exercise improves brain functions by regulating glial activation in numerous CNS diseases, including AD, Parkinson's Diseases and ischemic stroke [60, 149, 150]. Physical exercise could activate cellular and molecular pathways contributing to neuroplasticity [4, 151].

What are the symptoms of glial cells? ›

Glial cell activation and neuroinflammation are the underlying causes of centralized pain and its associated comorbidities, including depression, fatigue, and insomnia.

Do glial cells cause depression? ›

Among the different lines of research, recent literature suggests that impaired neuron and glial plasticity may be a key underlying mechanism in the precipitation of the disorder. Surprisingly, glial cells appear to be involved both in the pathophysiology of major depression and in the action of antidepressants.

Does COVID affect glial cells? ›

Glial Cells in the Pathophysiology of COVID-19

Specifically, astrocytic injury was observed in the acute phase of COVID-19, as shown by high plasma levels of glial fibrillary acidic protein (GFAP), with more pronounced findings in hospitalized patients (Kanberg et al., 2020).

Are glial cells good or bad? ›

Primarily, glial cells provide support and protection to the neurons ( nerve cells ), maintain homeostasis, cleaning up debris, and forming myelin. They essentially work to care for the neurons and the environment they are in.

Do glial cells help with memory? ›

Over the past two decades, research on glial cells, particularly on a specific type called the astrocyte, has revealed the key role they play in brain function. Astrocytes provide energy for neurons and support synaptic plasticity during higher brain processes such as learning, memory and cognition.

What part of the brain has glial cells? ›

In the mature brain, the cerebellum and retina retain characteristic radial glial cells. In the cerebellum, these are Bergmann glia, which regulate synaptic plasticity.

Can glial cells become cancerous? ›

A glioma is a tumor that forms when glial cells grow out of control. Normally, these cells support nerves and help your central nervous system work. Gliomas usually grow in the brain, but can also form in the spinal cord. Gliomas are malignant (cancerous), but some can be very slow growing.

Why do glial cells become cancerous? ›

Gliomas are believed to arise from genetic mutations (changes) of glial cells. When the genetic makeup of these cells becomes mutated, abnormal tissue growth can lead to tumors such as glioma and glioblastoma.

Do glial cells provide energy? ›

The primary source of energy is blood-born glucose, but the glial cells serve as important hubs of energy transfer. They take up glucose and provide glycolysis-derived lactate to distant neuronal compartments, such as synapses (Pellerin and Magistretti, 1994) and myelinated axons (Fünfschilling et al., 2012).

What do glial cells do everyday? ›

Functions include: clean up brain "debris"; transport nutrients to neurons; hold neurons in place; digest parts of dead neurons; regulate content of extracellular space; promote synaptic connections; clear excess neurotransmitters; ensure the continued function of neurons.

What is the ratio of glia to neurons? ›

60.84 billion cells in the cerebral cortex are glia, while only 16.34 billion cells are neurons, giving this large region a glia to neuron ratio of about 3.76 to 1. It's the inverse in the cerebellum, an evolutionarily ancient part of the brain that sits astride the brain stem.

What is the ratio of microglia to neurons in the brain? ›

We found that microglial cells constitute ∼7% of non-neuronal cells in different brain structures as well as in the whole brain of all mammalian species examined.

What percentage of the brain are neurons? ›

Generic rodent brainHuman brain
Relative number of neurons in cerebral cortex17% of brain neurons19% of brain neurons
Mass, cerebellum133 g154 g
Neurons, cerebellum10 billion69 billion
Relative size of the cerebellum9% of brain mass10% of brain mass
6 more rows

What is the ratio of astrocytes to neurons in the brain? ›

The ratio of astrocytes to neurons in the natural brain cortex is normally between 1:2 and 1:3 [34]. In this study, the volume of neurons was larger than that of astrocytes. Therefore, a larger ratio (1:2) was chosen for the N&A-L group.

What percentage of brain cells are glia? ›

Ben Barres' research has led to a greater appreciation of glial cells, which comprise 90 percent of the brain.

Are over 60% of all brain cells are neurons? ›

Over 60% of all brain cells are neurons. The first nerve cell receiving an impulse directly from a receptor is called a motor or efferent neuron. The action potential moves in both directions down a nerve fiber.

Does the number of neurons affect intelligence? ›

Thus, larger and more complex pyramidal neurons in temporal association area may partly contribute to thicker cortex and link to higher intelligence.

Does number of neurons affect IQ? ›

IQ scores are correlated with the morphology and activity of certain neurons in the human temporal cortex.

Does brain size affect number of neurons? ›

Strikingly, we found that the increase in relative size of the cerebral cortex in larger brains does not reflect a relatively larger number of cortical neurons compared with the whole brain, or with the cerebellum. Larger cortices do have larger numbers of neurons, of course (Fig.

Which part of the brain contains over 50% of the total number of neurons? ›

Although the cerebellum accounts for approximately 10% of the brain's volume, it contains over 50% of the total number of neurons in the brain.

What are 60% of brain cells? ›

The brain is composed of 40 percent gray matter, which is made of neurons, and 60 percent white matter, which is made of dendrites and axons that the neurons utilize.

Videos

1. Stem cells to nerve cells short animation video | #medical
(Learn biology With Musawir)
2. OSSM Neuro Chapter 23 - Neurogenesis
(Brent Richards)
3. Neuroglia of the CNS
(Dr. Elder's Anatomy Channel)
4. The Neuron Doctrine: The beginning of neuroscience
(neurally)
5. How Neurotransmitters Are Transported: Psychotropic Transporters
(NEI Psychopharm)
6. Nerve fiber and nerve
(Bionet)

References

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