What are the most important cells in the nervous system?
|
If you're seeing this message, it means we're having trouble loading external resources on our website. Show If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. The nervous system transmits signals between the brain and the rest of the body, including internal organs. In this way, the nervous system’s activity controls the ability to move, breathe, see, think, and more. The basic unit of the nervous system is a nerve cell, or neuron. The human brain contains about 100 billion neurons. A neuron has a cell body, which includes the cell nucleus, and special extensions called axons (pronounced AK-sonz) and dendrites (pronounced DEN-drahytz). Bundles of axons, called nerves, are found throughout the body. Axons and dendrites allow neurons to communicate, even across long distances. Different types of neurons control or perform different activities. For instance, motor neurons transmit messages from the brain to the muscles to generate movement. Sensory neurons detect light, sound, odor, taste, pressure, and heat and send messages about those things to the brain. Other parts of the nervous system control involuntary processes. These include keeping a regular heartbeat, releasing hormones like adrenaline, opening the pupil in response to light, and regulating the digestive system. When a neuron sends a message to another neuron, it sends an electrical signal down the length of its axon. At the end of the axon, the electrical signal changes to a chemical signal. The axon then releases the chemical signal with chemical messengers called neurotransmitters (pronounced noor-oh-TRANS-mit-erz) into the synapse (pronounced SIN-aps)—the space between the end of an axon and the tip of a dendrite from another neuron. The neurotransmitters move the signal through the synapse to the neighboring dendrite, which converts the chemical signal back into an electrical signal. The electrical signal then travels through the neuron and goes through the same conversion processes as it moves to neighboring neurons. The nervous system also includes non-neuron cells, called glia (pronounced GLEE-uh). Glia perform many important functions that keep the nervous system working properly. For example, glia:
The brain is made up of many networks of communicating neurons and glia. These networks allow different parts of the brain to “talk” to each other and work together to control body functions, emotions, thinking, behavior, and other activities.,, The brain is a mosaic made up of different cell types, each with their own unique properties. The most common brain cells are neurons and non-neuron cells called glia. The average adult human brain contains approximately 100 billion neurons, and just as many—if not more—glia. Although neurons are the most famous brain cells, both neurons and glial cells are necessary for proper brain function. NeuronsWhen you think of the brain, you probably think of neurons. Neurons are the cells in the brain that send and receive electrical and chemical signals. They are building blocks of your brain, and transmit information to other neurons, muscles, and tissues throughout the body. They allow you to think, feel, move, and comprehend the world around you. A neuron is made up of three basic parts: the cell body, or soma; branching dendrites that receive signals from other neurons; and the axon, which sends signals out to surrounding neurons through the axon terminal. When a neuron fires an action potential, electric and chemical signals spread from the axon of one neuron to the dendrites of another neuron across a small gap called the synapse. (Read our fact sheet “How Does the Brain Work?” to learn more.)  GliaLike neurons, glia are important cells of the nervous system. Scientists used to think that glia were like glue, only for holding the neurons in place. The name “glia” is Latin for “glue.” However, we now know that glial cells are not just brain glue. In fact, glia actively participate in brain signaling, and are necessary for the healthy function of neurons. Unlike neurons, glial cells cannot fire action potentials to communicate messages, but that does not mean they are inactive. Glia communicate to each other and to neurons using chemical signals, and can even respond to many of the same chemicals that neurons can, such as ions and neurotransmitters. This means that glia can eavesdrop on the neurons, to help strengthen the messages that are passed between them. There are many types of glial cells in the brain. Here are three important glial cell types: Oligodendrocytes: A special type of glial cell known as an oligodendrocyte wraps around the axons of neurons, making up what is known as the myelin sheath. Like insulation around an electrical wire, oligodendrocytes insulate the axon and help neurons pass electrical signals at incredible speed and over long distances.
Research highlight Recently, scientists are discovering new roles for glial cells in disease. Normally, glia protect and help neurons, but when they malfunction, they can cause serious damage. Animal studies have shown that inflammation caused by glia is associated with many diseases such as Parkinson’s, Alzheimer’s, and multiple sclerosis. This type of research is important because it allows scientists to examine human diseases in animal models. As we continue to learn more about glia, we will be able to use this information to treat these diseases. Download this page as a PDF Find out more: Go to BrainFacts.org to check out a Beth Stevens, Ph.D., and Staci Bilbo, Ph.D., wrote an article for us called “Microglia: The Brain’s First Responders.” What cells are the most common cells in the nervous system?As a whole, glial cells are the most abundant cells in the central nervous system. The most notable glial cells include oligodendrocytes, Schwann cells, astrocytes, microglia, and ependymal cells.
What are the most important cells in the brain?The central nervous system (which includes the brain and spinal cord) is made up of two basic types of cells: neurons (1) and glia (4) & (6). Glia outnumber neurons in some parts of the brain, but neurons are the key players in the brain.
What are the main cells in the central nervous system?Major cell types of the central nervous system comprise neurons, glial cells (astrocytes, oligodendrocytes, ependymal cells, and microglia), choroid plexus cells, cells related to blood vessels and coverings.
What are the three cells of the nervous system?The cells in nervous tissue that generate and conduct impulses are called neurons or nerve cells. These cells have three principal parts: the dendrites, the cell body, and one axon.
|
