Nerves are your body’s wiring system. They carry electrical and chemical signals between your brain, spinal cord, and every other part of your body, enabling everything from feeling a hot stove to digesting your lunch to pulling your hand away before you even realize what happened. Without nerves, no sensation, movement, or automatic body function would be possible.
The Three Types of Nerves
Your nervous system uses three functional categories of nerves, each with a distinct job.
Sensory nerves carry information from your body to your brain. These are the nerves that let you feel pressure on your skin, taste food, smell coffee, hear a conversation, and see the world around you. They’re constantly collecting data from your environment and internal organs and sending it to the brain for processing.
Motor nerves work in the opposite direction. They carry commands from your brain and spinal cord out to your muscles and glands, telling them what to do. Every deliberate movement you make, from typing to walking to speaking, depends on motor nerve signals reaching the right muscles at the right time.
Autonomic nerves handle everything your body does without you thinking about it: breathing, sweating, digesting food, and maintaining your heart rate. These nerves keep you alive while you sleep, and they adjust your body’s systems moment to moment based on what you need.
How Nerves Send Signals
Nerve signals are electrochemical events. At rest, the inside of a nerve cell sits at about -70 millivolts compared to the outside, a tiny electrical charge maintained by the flow of charged particles (ions) through channels in the cell’s membrane. When a nerve cell receives enough input from other cells, its voltage rises to a threshold of about -50 millivolts. At that point, the cell fires what’s called an action potential: a rapid electrical spike lasting roughly one millisecond that travels down the length of the nerve fiber.
Many nerve fibers are wrapped in a fatty insulating layer called myelin. This sheath dramatically speeds up signal transmission, allowing impulses to jump along the nerve rather than crawl. When myelin is damaged, as it is in conditions like multiple sclerosis, those signals slow down or fail entirely, causing weakness, numbness, or coordination problems.
When an electrical signal reaches the end of one nerve cell, it needs to cross a tiny gap (the synapse) to reach the next cell. The arriving signal triggers small packets of chemical messengers, called neurotransmitters, to release into that gap. These molecules drift across and lock onto receptors on the next cell, either activating it or quieting it down. This chemical handoff is how signals pass between nerve cells, and between nerves and muscles or glands. The entire process takes fractions of a second and repeats billions of times a day across your body.
How Autonomic Nerves Regulate Your Body
Your autonomic nerves split into two opposing systems that work like a gas pedal and a brake. The sympathetic system activates your “fight or flight” response: it speeds up your heart, opens your airways, and redirects blood to your muscles when you’re stressed or in danger. The parasympathetic system does the opposite, calming things down during rest.
The parasympathetic system’s reach is remarkably wide. It slows your heart rate and reduces how hard your heart pumps. It constricts your pupils and improves close-up vision. It ramps up digestion and tells your pancreas to release insulin so your cells can use sugar for energy. It triggers saliva production in your mouth and mucus in your nose. It relaxes the muscles that control your bladder and bowels and manages aspects of sexual arousal.
These two systems constantly negotiate with each other. After a meal, parasympathetic activity increases to prioritize digestion. During exercise, sympathetic activity takes over to boost your cardiovascular output. You never consciously decide to do any of this. Your autonomic nerves handle it automatically, adjusting dozens of processes simultaneously to match what your body needs in that moment.
What Happens When Nerves Are Damaged
Nerve damage, often called neuropathy, tends to show up first in the hands and feet. Early symptoms typically include numbness, tingling, pain, or burning sensations in a “stocking and glove” pattern, meaning the areas that socks and gloves would cover. About one-third of people with peripheral neuropathy experience significant nerve pain, which can feel like stabbing, electric shocks, or heightened sensitivity where even light touch becomes painful.
As damage progresses, it can move closer to the trunk and cause muscle weakness or shrinking (atrophy) in the affected areas. Because autonomic nerves can also be affected, some people develop digestive problems, dizziness when standing up, changes in bladder or bowel function, dry eyes, or blurred vision. Diabetes is one of the most common causes of this kind of nerve damage, but it can also result from injuries, infections, autoimmune conditions, and nutritional deficiencies.
Signs of long-standing neuropathy include calf muscle wasting, curled (hammer) toes, and high foot arches. These physical changes can suggest hereditary forms of nerve disease that have been progressing for years before symptoms became noticeable.
Can Nerves Heal?
Nerves in the brain and spinal cord (the central nervous system) have very limited ability to regrow after injury. Peripheral nerves, the ones running through your arms, legs, and torso, are a different story. They can regenerate, but slowly. The standard rate of peripheral nerve regrowth is approximately 1 millimeter per day. That means if a nerve in your arm is injured several inches from the muscle it controls, recovery could take months. The further the damage is from its target, the longer the wait.
This slow pace explains why recovery from nerve injuries and surgeries requires patience, and why early treatment matters. The longer a nerve is compressed or severed, the harder full recovery becomes, because the muscle at the other end can weaken and atrophy while waiting for signals to return.