The nervous system has two main parts: 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.1 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.1,2,3
Your nervous system is your body’s command center. Originating from your brain, it controls your movements, thoughts and automatic responses to the world around you. It also controls other body systems and processes, such as digestion, breathing and sexual development (puberty). Diseases, accidents, toxins and the natural aging process can damage your nervous system.
Your nervous system guides almost everything you do, think, say or feel. It controls complicated processes like movement, thought and memory. It also plays an essential role in the things your body does without thinking, such as breathing, blushing and blinking. Your nervous system affects every aspect of your health, including your:
This complex system is the command center for your body. It regulates your body’s systems and allows you to experience your environment. A vast network of nerves sends electrical signals to and from other cells, glands, and muscles all over your body. These nerves receive information from the world around you. Then the nerves interpret the information and control your response. It’s almost like an enormous information highway running throughout your body.
Your nervous system uses specialized cells called neurons to send signals, or messages, all over your body. These electrical signals travel between your brain, skin, organs, glands and muscles. The messages help you move your limbs and feel sensations, such as pain. Your eyes, ears, tongue, nose and the nerves all over your body take in information about your environment. Then nerves carry that data to and from your brain. Different kinds of neurons send different signals. Motor neurons tell your muscles to move. Sensory neurons take information from your senses and send signals to your brain. Other types of neurons control the things your body does automatically, like breathing, shivering, having a regular heartbeat and digesting food.
The nervous system has two main parts. Each part contains billions of cells called neurons, or nerve cells. These special cells send and receive electrical signals through your body to tell it what to do. The main parts of the nervous system are: Central nervous system (CNS): Your brain and spinal cord make up your CNS. Your brain uses your nerves to send messages to the rest of your body. Each nerve has a protective outer layer called myelin. Myelin insulates the nerve and helps the messages get through. Peripheral nervous system: Your peripheral nervous system consists of many nerves that branch out from your CNS all over your body. This system relays information from your brain and spinal cord to your organs, arms, legs, fingers and toes. Your peripheral nervous system contains your:
Thousands of disorders and conditions can affect your nerves. An injured nerve has trouble sending a message. Sometimes it’s so damaged that it can’t send or receive a message at all. Nerve injury can cause numbness, a pins-and-needles feeling or pain. It may be difficult or impossible for you to move the area that’s injured. Nerve damage can happen in several ways. Some of the most common causes of nerve damage include:
How common are these conditions?Some causes of nerve damage occur more frequently than others. They include:
Your nervous system is the command center for your entire body. It needs care to keep working correctly. See your doctor regularly, eat a healthy diet, avoid drugs, and only drink alcohol in moderation. The best way to avoid nerve damage from disease is to manage conditions that can injure your nerves, such as diabetes.
Call your doctor right away if you have any sudden changes in your health, such as losing coordination or noticing severe muscle weakness. You should also see your doctor if you have:
Last reviewed by a Cleveland Clinic medical professional on 05/12/2020. References
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy |