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The Cells of the Brain:
Neurons and Glial Cells
The Cells of the Brain:
Neurons and Glial Cells
The brain is composed of many types of cells, but the
functional unit is called the NEURON. All sensations,
movements, thoughts, memories, and feelings are the result
of signals that pass through neurons. The other cells in the
brain are the glial cells, which have important roles in the
functioning of the neuron.
The Neuron Consists of Three Parts:
1. Cell Body: contains the nucleus where most of the
molecules that the neuron needs to live and function are
made.
Neuron consisting of three parts: Cell Body,
Dendrites, and Axon.
2. Dendrites:
• Structures which extend out from the cell body like
branches of trees.
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Receive messages from other neurons.
The message is sent to the cell body then down an
axon.
3. Axon: Structure which extends out from the cell body
which is important for sending information to other
neurons.
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Axon Terminal: specialized ending that relays
information to other neurons.
Astrocytes
Neuronal Function: The Synapse
Scientists have learned a great deal about
neurons by studying the synapse, the place where
a signal passes from the neuron to another
neuron.
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When a signal reaches the end of the axon
it stimulates the release of chemicals
called neurotransmitters from small
storage sacs into the space between the
two neurons.
The neurotransmitter crosses the space
and attaches to receptors.
These receptors can change the properties
of the receiving neuron.
Synapse
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Examples of Neurotransmitters and
Their Role in the Brain
Acetylcholine
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GABA
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Acetylcholine generally makes cells more excitable.
Alzheimer’s disease, which affects memory formation, is associated with a shortage of
acetylcholine.
GABA tends to make neurons less excitable.
Medications that increase GABA levels in the brain have been used to treat seizures and
tremors in patients.
Serotonin
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Serotonin is a neurotransmitter that is involved in behavior, mood, appetite, and pain.
Medications that cause the brain’s levels of serotonin to increase have been used to treat
depression.
Dopamine
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Dopamine is involved in mood and the control of muscle movement.
The loss of dopamine in some parts of the brain can lead to Parkinson’s disease.
Glial Cells
Gial cells provide support for the brain, assisting in repair and maintenance, assiting in the
development of the nervous system, and providing metabolic functions for neurons.
Types of Glial Cells
Astrocytes
• Astrocytes get their name from their “star” shape.
• Astrocytes surround capillaries and form the “blood
brain barrier” that restricts what substances can
enter the brain.
• Astrocytes store nutrients for use by the neurons.
Oligodendrocytes
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Oligodendrocytes cover the axons of the neurons
providing the “myelin” sheath.
The Schwann cell provides this same function in the
peripheral neurons.
Microglial Cells
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Microglial cells are a specialized white blood cell in
the brain.
Recognizes foreign substances and destroys them.
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Neuronal Malfunction
Neuronal Malfunction can occur in the following ways:
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Loss of Neurons - This occurs in a stroke where part of the brain tissue dies.
Loss of Myelin - Multiple Sclerosis is a disease where the myelin around the axon no longer is
present due to death of the oligodendrocytes.
Loss of Receptors for the Neurotransmitters - Myasthenia gravis is a disease where the receptors
for acetylcholine are destroyed rendering a loss of motor function.
Prepared by:
Grand Valley State University
Office of the Vice Provost for Health
Veterans Traumatic Brain Injury Education Project
Cook-DeVos Center for Health Sciences
301 Michigan St. NE, 500 CHS
Grand Rapids, MI 49503-3314
www.gvsu.edu/veteranstbi
Authored material: Theresa Bacon-Baguley, PhD, RN
References:
1.
NIH Publication No.11-3440d, http://www.ninds.nih.gov/disorders/brain_basics/ninds_neuron.htm
2.
Veterans TBI Education Project 8/8/2013
3.
Cells of the Central Nervous System. Alila Medical Images – www.alilamedicalimages.com
Copyright © 2013 Grand Valley State University
Version: 8/8/2013
The contents of the “Patient Education Handouts for Veterans and Their Families,” and the DVD collection, such as text, graphics, images, information obtained (collectively,
“The Content”) are offered as a courtesy for informational purposes only. The Content is not intended to be a substitute for medical, legal, or other professional advice,
diagnosis, or treatment. Grand Valley State University does not guarantee and is not liable for the content or accuracy of the information found in the Patient Education
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