How Many Brain Cells Does a Human Have?

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Practical Psychology

Our brain is a complicated, fascinating, mysterious place in our body. It contains our innermost thoughts and reflexes that may cause embarrassment. In an instant, our brains can regulate our body temperature or recall a memory from middle school. For better or for worse, we can thank our brain cells for just about everything that goes on inside our brain.

What do you know about brain cells? That we've got a lot? Can we grow brain cells back? Does alcohol kill brain cells? Some of these questions have yet to be answered, while some of these commonly-discussed answers are total myths! Let's discuss the basics of brain cells, from what they do to how many we actually have. Brain cells are important to protect, but it's worth knowing what you're protecting!

How Many Brain Cells Does a Human Have?

Neuroscientists answer this question by distinguishing between the two types of brain cells. The average human brain contains around 100 billion neurons. Estimates say that we could contain 1 trillion as many glial cells! 

What Are Brain Cells?

Cells are the tiniest living unit that make up all organisms. Our bodies are made up of billions upon billions of specialized cells: brain cells, kidney cells, skin cells, you name it! Brain cells are cells that make up our brain.

Most of the brain’s space is packed with brain cells and the nervous tissue that these cells make up. Less than a quarter of the area is extracellular space. It’s a good thing that we have so much nervous tissue in the brain. This tissue is what takes in sensory information, integrates it, and tells our bodies what to do about it!

Are Brain Cells and Neurons the Same Thing?

Yes and no. There are two major types of brain cells: neurons and glial cells. Neurons are the most common type of brain cells. Neuroscientists estimate that brains contain 100 billion neurons! When we study anatomy and functions of the brain, we’re likely talking about the work of the neurons.

Neurons are nerve cells that carry out all the functions that we have already described. Their structure is more than just the cell. They contain dendrites and axons that connect neurons together. This is how neurons are able to communicate throughout the brain and with the body.

The glial cells (also known as neuroglia) do have many functions, but most of them serve the neurons and allow them to do their work more effectively. Glial cells:

  • Support and protect neurons
  • Form myelin sheaths
  • Clean up debris
  • Feeding neurons

Despite their more “passive” role in the brain’s more exciting functions, glial cells are believed to be more numerous than neurons!

About the Lifespan of Neurons

You've probably heard the phrase "killing your brain cells." Maybe your parents told you that video games would kill your brain cells, or you've heard jokes about dying brain cells being the result of reality TV. We'll get to damaged brain cells in a bit, but know one thing first. Neurons can live a long time if you protect them.

Are we born with all the neurons we will ever have? That has been up for debate for a long time. Neuroscientists once believed that neurons could never grow as we age. Recent evidence suggests otherwise. What we know for sure is that brain cells can be damaged or killed by serious injury.

How Are Brain Cells Damaged?

With over 100 billion neurons that can live as long as you live, it's impossible to ever "run out." But you can damage or kill off some of these cells when you experience a traumatic brain injury.

The loss of specialized brain cells impedes the ability to collect sensory information and respond appropriately. But not all brain cell damage is permanent.

The symptoms from injuries like concussions may actually be due to the death of brain cells. Once brain cells die, glial cells must go in and "clean up the mess." Failing to do so may cause problems later in life.

Scientists are still working to determine when our brain cells die. Initial scans may not show the severity of a brain injury, but certain blood tests may give doctors a better picture of what is to come.

Brain cell damage is also why we see curious cases after brain injuries. The average neuroscience 101 class describes the case of Phineas Gage, whose personality changed after a brain injury. Brain injuries may also cause psychiatric disorders.

Can Alcohol Kill Brain Cells?

This is actually a myth! Alcohol cannot kill a brain cell in the way that a traumatic head injury can kill a brain cell. Rather, alcohol can harm parts of the neurons that do impede communication. Studies have also shown that drinking alcohol in excessive amounts can "shrink" the hippocampus.

Can Brain Cells Die From Stress?

Binge drinking may not directly kill brain cells, but stress can. That's how dangerous stress can be to the body!

When we are stressed, our brains instruct the release of cortisol. This stress hormone is part of our daily functioning and can even be helpful, but in excess, it's dangerous. Long-term chronic stress can lead to long-term brain damage. Stress may also be linked to the development of neurodegenerative diseases like Alzheimer's.

The next time you find yourself relaxing by the pool or goofing off with friends, remind yourself that you are treating your brain well!

Does Alzheimer's Disease Kill Brain Cells?

Yes. This tragic neurodegenerative disease starves, cuts off support, and ultimately kills brain cells. This happens around the hippocampus first, which is why memory loss is often the first sign of the disease. Unfortunately, the disease doesn't stop there. Alzheimer's disease is widespread and may affect many areas of the brain. Once it has progressed enough, a person with Alzheimer's may lose the ability to function and sustain themselves. 

Can Brain Cells Regenerate?

Neurons don't work like skin cells. Skin cells tend to regenerate every month or so, but brain cells don't work in the same way. New evidence shows that brain cells may continue to grow, but this doesn't happen automatically. Certain activities, like aerobic activity or learning new information, aids neurogenesis.

There is a lot that we do not know about neurogenesis, because we didn't even think it was possible until recently! But we do know that neurogenesis happens most frequently in the hippocampus. Up to 1,500 new neurons may be created each day, as long as we continue to support our brains.

Stress and alcohol may prevent neurogenesis from being performed effectively in the brain.

Brain Cells and Neuroplasticity

When reading about brain cells and brain health, you might have come across the term "neuroplasticity." Neuroplasticity is slightly different from neurogenesis. In addition to growing new cells, the structure of the brain and the connections made between the cells may change. This is neuroplasticity.

Like neurogenesis, neuroscientists believe that new experiences and new information aids neuroplasticity. Luckily, you've learned something new and gained new experiences today! Keep learning, stay healthy, and you can support the hundreds of billions of brain cells in your body!

Reference this article:

Practical Psychology. (2022, April). How Many Brain Cells Does a Human Have?. Retrieved from

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