What Is Your Nervous System?

Medically Reviewed by Zilpah Sheikh, MD on April 21, 2025
Written by Danny Bonvissuto, Evan Starkman
10 min read

Your nervous system is your body's main communication system. It sends messages from your brain to the rest of your body and helps you respond to changes inside and around you.

Your brain, spinal cord, and nerves are the main parts of your nervous system. Important messages travel back and forth from your brain. They travel through your spinal cord and out to nerves that extend like wires throughout your body. Your nervous system uses billions of tiny, connected nerve cells called neurons to send the messages, which are electrical and chemical signals that tell your body what to do.

Everything your body does is connected in some way to your nervous system. It tells your heart to beat and your lungs to breathe. It controls the way you move, the words you say, and how you think and learn. It also controls your senses and memories.

The messages traveling in your nerves are sent through billions of nerve cells called neurons. The spaces between these cells are called synapses. The cells are linked to one another through chemicals called neurotransmitters that move across the synapses to the next neuron. Dopamine and serotonin are types of neurotransmitters.

This process continues until the message gets to the right place. Some messages move faster than 200 miles per hour.

This is also how messages get from your body back to your brain and spinal cord. For example, if you step on something sharp, the nerves in your foot send a message through neurons to your central nervous system that says, "Hey, this hurts." Your brain and spinal cord respond with a message to your foot: "Pull away now."

Your nervous system is made of key organs and fiber bundles that enable you to live, function well, and be yourself.

Nervous system organs

Your brain is like a supercomputer that controls every function in your body. Weighing 3 pounds on average, this organ is responsible for your mental abilities, such as thinking, emoting, learning, and remembering. It also controls vital processes you don't have to think about, such as your heart rate, breathing, and blood pressure.

Your brain receives and processes information from sense organs such as your eyes, nose, and ears. And it sends signals to your body that let you do what you want, like moving and talking.

The brain alone has more than 100 billion neurons to send and receive these signals, or messages.

Your spinal cord is a column of tissue that runs from the lower part of your brain to your lower back. It's a bundle of nerves and cells that relays messages between your brain and the rest of your body.

Your nerves are bundles of fibers that connect your brain to the rest of your body. They're like cables that carry messages, helping your body work as it should. Nerves help you do everything from feeling and moving to breathing and digesting food.

Because your nervous system does so many important jobs, experts divide it up into different parts.

Central nervous system

This is made up of your brain and spinal cord. It's like a command center that communicates with the rest of your body, receiving and sending messages constantly.

Because your brain is so important, it's surrounded by your skull for protection. And your spinal cord is guarded by the bones that make up your spine. Both your brain and spinal cord are cushioned by three thin layers of tissue called the meninges. Plus, a liquid called cerebrospinal fluid flows in and around the hollow spaces of the brain and spinal cord, providing more cushion.

Peripheral nervous system

This is the network of nerves beyond your brain and spinal cord. These nerves play key roles in helping you use your senses and move your muscles. They also help your brain run vital processes you don't have to think about, such as managing your heart rate and blood pressure.

Your peripheral nerves branch out from your spinal cord to everywhere else in your body, including your organs, arms, hands, legs, and feet. This allows the messages to be exchanged between your brain and body.

Your peripheral nervous system is further divided into two main parts: the autonomic and somatic nervous systems.

Autonomic nervous system

This is the part of your peripheral nervous system that controls the muscles of organs without you having to think about it. Your autonomic nervous system lets your brain manage vital functions, such as breathing, heart rate, blood pressure, and food digestion.

This system is divided into two parts that balance each other out. One part, called your sympathetic nervous system, helps you fight or run away in an emergency (also known as your "fight-or-flight" response). The other part, called your parasympathetic nervous system, helps your body relax, get rest, and digest food.

Somatic nervous system

This is the part of your peripheral nervous system that's in charge of processes that you're aware of. For instance, the somatic nervous system lets you control muscles and perceive touch, taste, smell, and sound. What's more, it can help you sense pain in a certain part of the body that actually started in an internal organ and spread nearby. This is called referred pain. For instance, you might feel heart attack pain in your back, jaw, left arm, or stomach area.

Your nervous system has lots of protection. For instance, your brain is guarded by your skull, and your spinal cord is shielded by small bones in your spine. Still, things can go wrong with your nervous system just like with any other part of your body.

Nervous system infections

Germs can infect your nervous system and cause diseases. Some examples are:

  • Meningitis, inflammation of the fluid and tissue layers around the brain and spinal cord, most often caused by a virus
  • Encephalitis, inflammation of the brain caused by a virus or bacteria
  • Brain abscess, a collection of pus and infected material in your brain that can be caused by bacteria or fungi
  • Polio, a rare viral illness that mainly affects nerves in the brain stem or spinal cord

Injuries to the nervous system

Accidents or health conditions that can injure parts of the nervous system include:

  • Brain, spine, or nerve trauma, due to things such as a car accident, sports injury, fall, stroke, or gunshot
  • Carpal tunnel syndrome, a common hand injury due to too much pressure on a key nerve in the wrist
  • Pinched nerve, which is when surrounding tissues like bones or muscles put too much pressure on a nerve
  • Diseases such as lupus and rheumatoid arthritis that cause the immune system to go haywire, possibly injuring peripheral nerves in the process
  • Peripheral neuropathy, the name for conditions that damage one or more of the peripheral nerves beyond your brain or spinal cord

Nervous system disorders

Some conditions that affect how the nervous system works are:

  • Parkinson's disease, a brain condition that affects movement and worsens over time
  • Multiple sclerosis, a disease that damages the protective covering around nerves and leads to weakness, numbness, trouble walking, and other symptoms
  • Alzheimer's disease, the most common type of dementia that over time leads to serious memory loss and trouble doing everyday tasks
  • Amyotrophic lateral sclerosis (ALS), a disease that affects brain and spinal cord nerve cells, causing a loss of muscle control that worsens over time

Blood vessel issues

Conditions that can affect blood vessels can also damage the nervous system. These include:

  • Stroke, an emergency that can happen when a blood vessel leaks or breaks, keeping the brain from getting enough blood
  • Transient ischemic attack (TIA), a short-term blockage of blood to the brain that's often due to plaque buildup in an artery
  • Subdural hematoma, a type of bleeding close to the brain that happens due to a tear in a blood vessel, most often after a head injury

Symptoms of nerve problems vary. They partly depend on the type of nerve that's affected.

Motor nerves control your muscles and movement. A problem that affects these nerves might cause symptoms such as:

  • Achy, weak, twitching, or cramping muscles
  • Shrinking muscles
  • Trouble balancing or walking
  • Problems with using your arms and hands

Sensory nerves let you perceive things like touch, temperature, and pain. A problem that affects these nerves might cause symptoms such as:

  • Numbness, tingling, or pain that often happens in your hands and feet
  • Less ability to feel heat, cold, or pain
  • Trouble walking, staying balanced while your eyes are closed, or fastening buttons
  • Pain that flares up even from a gentle touch

Autonomic nerves help control vital processes, such as your breathing and heart rate, without any conscious thought. A problem that affects these nerves might cause symptoms such as:

  • Fast or slow heartbeats
  • Blood pressure changes
  • Trouble swallowing
  • Very sensitive to heat
  • Sweating a lot or too little
  • Throwing up, diarrhea, or constipation
  • Trouble peeing or having sex

Conditions that don't affect your nerves can also cause many of these symptoms. So, talk with your doctor to find out what's going on with you.

You can make some lifestyle changes at home to help take care of your nervous system.

Nervous system and nutrition

The foods you put on your plate play a role in the long-term health of your brain, says Aaron Nelson, MD, MBS, FAAP, FAAN, FCNS, a professor of neurology and director of the child neurology residency training program at NYU Grossman School of Medicine.

Nelson says that brain-healthy foods have nutrients such as:

Omega-3 fatty acids. You can get these from fatty fish, such as salmon, albacore tuna, mackerel, herring, and farmed trout. You can also get omega-3s from nuts and seeds (like flaxseed, chia seeds, and walnuts) and plant oils (like flaxseed oil, soybean oil, and canola oil).

B vitamins. These are found in poultry, fish, eggs, ground beef, plain yogurt, organ meats, potatoes and other starchy vegetables, chickpeas, fortified cereals, and fruits other than citrus.

Antioxidants. You can get these by eating a variety of colorful fruits and vegetables. Whole grains, nuts, seeds, herbs and spices, and cocoa also have antioxidants.

Whenever you can, aim to eat and cook with whole foods that are in their natural state. And cut back on highly processed foods that are often prepackaged and may lack key nutrients.

"There seems to be clear evidence that having more whole foods leads to better brain health in the long run," Nelson says. "There's a lot of really important things that we find in natural fruits and vegetables and other foods that aren't found in processed foods."

If you can't eat a varied diet full of nutritious foods, "one of the best things you can do long-term for your brain health is just [take] a simple multivitamin," Nelson says.

Nervous system and stress

Your sympathetic nervous system, which prepares your body to respond to stress or danger, becomes more active when you're stressed out. For instance, it boosts your heart rate and breathing ability. But if you have ongoing stress or anxiety, it can take a toll on your sympathetic nervous system.

"If you're feeling very, very stressed or anxious, there's direct things you can do," Nelson says. "You can deliberately take long and deep breaths. You can splash water on your face. Sometimes people will run their wrists under cold water and find that it's very calming."

Nelson also recommends aerobic activities, such as walking or swimming. You could also try calming activities, such as meditation, yoga, or tai chi. Also, aim to get enough sleep — about seven to nine hours a night for most adults.

If DIY stress-busters don't help enough, talk with your doctor. They might suggest medicines to ease anxiety or excessive stress.

For people who don't get enough relief from medication, other treatments might be options. One procedure stimulates nerve cells in the brain by using magnetic fields. This is called transcranial magnetic stimulation, and it's done outside of your body without cuts or surgery. It can help with hard-to-treat depression or anxiety, Nelson says.

Vagus nerve stimulation is another procedure that might be helpful, especially for people with the most severe depression or anxiety, Nelson says. This involves surgery to place a device that sends electrical impulses to the vagus nerve, which passes through your neck. Your vagus nerve is a key part of the parasympathetic nervous system that helps you relax.

Your nervous system sends messages from your brain to the rest of your body. It also responds to changes both inside and outside of your body. Your brain, spinal cord, and nerves are the main parts of your nervous system. To help take care of your nervous system, eat a variety of nutritious foods, cut back on processed foods, and manage your stress.

What are the symptoms of a damaged nervous system?

The symptoms can vary widely depending on the cause of the damage. They might include headaches, numbness or tingling, weakened or rigid muscles, vision problems, worse memory or mental ability, trouble with coordination, shaking and seizures, slurred speech, trouble speaking or understanding speech, and back pain that spreads to the other body parts such as the feet.

What is the most common cause of damage to the nervous system?

"There are many different causes, and it depends a lot on age and life circumstances," Nelson says. "But the most common thing that happens to people across the entire lifespan is essentially some version of a knock to the head. In children, most often it's concussion. Though concussion, if it's more severe, can be a traumatic brain injury. In adults, I think a lot of concussion goes unnoticed, and so the answer for that would be traumatic brain injury."

Nelson recommends taking simple steps to protect your brain. For instance, wear a good helmet during impact sports or biking, and always put on a seatbelt when you're in the car.