What Is Function of Nervous System?

The nervous system coordinates all bodily actions by transmitting electrical and chemical signals between the brain and various body parts. This complex network consists of the brain, spinal cord, and billions of nerve cells that work together to control everything from voluntary movements like walking to involuntary processes like heartbeat regulation. The system processes sensory information from your environment, makes decisions, and executes responses—all within milliseconds.

Your nervous system manages three fundamental operations: receiving sensory input from internal and external environments, integrating and interpreting this information, and generating appropriate motor responses. These operations occur through approximately 100 billion neurons in the brain alone, each forming thousands of connections with other neurons. Whether you’re reading these words, maintaining your balance, or digesting food, your nervous system orchestrates these activities simultaneously through specialized pathways and structures.

Primary Functions of the Nervous System

The nervous system performs four essential functions that enable survival and interaction with the environment. Each function operates through distinct but interconnected pathways.

Sensory Reception and Processing

Specialized sensory neurons detect changes in your environment through receptors distributed throughout your body. These receptors monitor temperature, pressure, pain, light, sound, and chemical concentrations. When you touch a hot surface, for instance, sensory neurons in your skin immediately detect the temperature change and convert this physical stimulus into electrical signals.

The nervous system processes millions of sensory inputs simultaneously. Your eyes detect photons of light, your ears respond to sound waves, and your skin registers pressure variations—all sending concurrent streams of information to your brain. In 2021, researchers found that sensory processing disorders affect a significant portion of the 3.4 billion people worldwide living with neurological conditions.

Information Integration

After receiving sensory data, your central nervous system integrates this information to create a coherent understanding of your situation. This integration happens primarily in the brain, where interneurons—neurons that connect other neurons—analyze incoming signals and determine appropriate responses.

Integration isn’t simply about processing single inputs. Your brain combines information from multiple senses, compares it with stored memories, and considers your current goals. When crossing a street, you integrate visual data about traffic, auditory information about approaching vehicles, and proprioceptive feedback about your body position to make split-second decisions.

Motor Output and Response Generation

Motor neurons transmit commands from your central nervous system to muscles and glands throughout your body. These neurons control both voluntary movements—like typing or speaking—and involuntary actions such as breathing and digestion.

The motor system operates through two pathways. Upper motor neurons originate in the brain and travel to the spinal cord, while lower motor neurons extend from the spinal cord to specific muscles. This two-neuron system allows for precise control over muscle contraction and relaxation, enabling complex movements from fine finger manipulations to coordinated athletic performances.

Homeostatic Regulation

Beyond conscious actions, your nervous system maintains internal stability through constant monitoring and adjustment of physiological processes. The autonomic nervous system regulates heart rate, blood pressure, body temperature, and digestive functions without requiring conscious thought.

This regulatory function divides into two complementary systems. The sympathetic nervous system prepares your body for action—increasing heart rate and redirecting blood flow during stress. The parasympathetic nervous system promotes rest and recovery—stimulating digestion and lowering heart rate during relaxation. These systems work in opposition to maintain balance across various conditions.

Structural Components and Their Roles

The nervous system’s functions depend on its anatomical organization into specialized regions and cell types.

The Central Nervous System

Your brain and spinal cord form the central nervous system, serving as the command center for all neural activity. The brain alone weighs approximately 1.4 kilograms and consumes about 20% of your body’s energy despite representing only 2% of body weight.

Different brain regions specialize in specific functions. The frontal lobe handles decision-making and voluntary movement, the parietal lobe processes sensory information, the temporal lobe manages memory and hearing, and the occipital lobe interprets visual data. The cerebellum coordinates movement and balance, while the brainstem controls vital functions like breathing and heart rate.

The spinal cord acts as a two-way communication highway, carrying sensory information to the brain and motor commands to the body. It also processes reflexes independently, allowing rapid responses without waiting for brain input. When you touch something hot, spinal reflexes can trigger muscle contraction before pain signals even reach your brain.

The Peripheral Nervous System

Extending from your central nervous system, the peripheral nervous system consists of 43 pairs of nerves—12 cranial nerves originating from the brain and 31 spinal nerves emerging from the spinal cord. These nerves branch extensively, creating a network that reaches every part of your body.

Peripheral nerves come in three types. Sensory nerves carry information from sensory receptors to the central nervous system. Motor nerves transmit commands from the central nervous system to muscles and glands. Mixed nerves, which make up most peripheral nerves, contain both sensory and motor fibers within the same nerve bundle.

Neurons: The Functional Units

Neurons are specialized cells designed for rapid communication. Each neuron contains a cell body, dendrites that receive signals from other neurons, and an axon that transmits signals to the next cell. Neurons communicate through synapses—junctions where electrical signals convert to chemical messengers called neurotransmitters.

Three categories of neurons perform distinct roles. Sensory neurons, typically pseudounipolar in structure, transmit information from sensory receptors to the central nervous system. Motor neurons, usually multipolar with multiple dendrites and one axon, carry commands from the central nervous system to muscles. Interneurons, located entirely within the central nervous system, connect sensory and motor neurons and enable complex processing.

Supporting Glial Cells

Neurons don’t work alone. Glial cells outnumber neurons roughly one-to-one in the human brain and provide essential support functions. Oligodendrocytes and Schwann cells form myelin sheaths around axons, dramatically increasing signal transmission speed. Astrocytes maintain the chemical environment around neurons and support the blood-brain barrier. Microglia act as immune cells, removing debris and damaged neurons.

How Signals Travel Through the Nervous System

Neural communication combines electrical and chemical processes to transmit information rapidly across your body.

Electrical Signal Propagation

Neurons maintain an electrical charge difference across their cell membranes through ion pumps that actively move sodium and potassium ions. At rest, the inside of a neuron is negatively charged relative to the outside—typically around -70 millivolts.

When a neuron receives sufficient stimulation, it generates an action potential—a rapid reversal of electrical charge that travels down the axon. This electrical signal moves at speeds ranging from 1 meter per second in unmyelinated fibers to over 100 meters per second in myelinated fibers. The myelin sheath acts as insulation, allowing signals to jump between gaps in the myelin, significantly accelerating transmission.

Chemical Transmission at Synapses

At the synapse, electrical signals convert to chemical messages. When an action potential reaches the axon terminal, it triggers the release of neurotransmitters into the synaptic cleft—a microscopic gap between neurons. These chemical messengers diffuse across the gap and bind to receptors on the next neuron.

Different neurotransmitters produce different effects. Glutamate and acetylcholine typically excite the receiving neuron, making it more likely to fire. GABA and glycine generally inhibit the receiving neuron, decreasing its likelihood of firing. The balance between excitation and inhibition determines whether a signal continues propagating through the neural network.

Reflex Arcs: Direct Response Pathways

Some responses require such rapid action that bypassing full brain processing proves beneficial. Reflex arcs create direct pathways from sensory neurons through the spinal cord to motor neurons, enabling responses within 50 milliseconds or less.

The knee-jerk reflex demonstrates this mechanism. Tapping the patellar tendon stretches the quadriceps muscle, activating sensory neurons. These neurons synapse directly with motor neurons in the spinal cord, which immediately signal the quadriceps to contract. Your leg extends before your brain consciously registers the tap—a survival mechanism that protects you from potential harm before conscious thought occurs.

Autonomic Nervous System Control

While voluntary actions capture our attention, the autonomic nervous system silently manages countless life-sustaining processes.

Sympathetic Activation

The sympathetic nervous system prepares your body for action in response to stress or danger. When activated, it increases heart rate and blood pressure, dilates airways to improve oxygen intake, redirects blood from digestive organs to skeletal muscles, and triggers glucose release from energy stores.

This “fight or flight” response evolved to handle acute threats. Modern stressors—work deadlines, traffic, financial concerns—can trigger the same physiological response, even when physical action isn’t required. Chronic sympathetic activation contributes to various health problems, including hypertension and digestive disorders.

Parasympathetic Restoration

The parasympathetic nervous system counterbalances sympathetic activity, promoting “rest and digest” functions. It slows heart rate, lowers blood pressure, stimulates digestive secretions and peristalsis, and promotes energy storage.

Parasympathetic activity dominates during relaxation and sleep, allowing your body to repair tissues, consolidate memories, and restore energy reserves. Activities that enhance parasympathetic tone—meditation, deep breathing, gentle exercise—support overall health and recovery from stress.

Enteric Nervous System

Your digestive tract contains its own nervous system—the enteric nervous system—sometimes called the “second brain.” This network of approximately 500 million neurons operates largely independently of the brain and spinal cord, controlling digestive motility, secretion, and blood flow.

The enteric nervous system communicates bidirectionally with the central nervous system through the vagus nerve. This gut-brain axis influences mood, stress responses, and even cognitive function. Recent research shows that disruptions in gut-brain communication may contribute to various neurological and psychiatric conditions.

Neurological Health and Disease Burden

Understanding nervous system function gains urgency given the substantial health impact of neurological conditions globally.

Global Disease Burden

According to a comprehensive 2024 analysis published in The Lancet Neurology, neurological conditions affected 3.4 billion people worldwide in 2021—representing 43% of the global population. These conditions caused 443 million disability-adjusted life years, making them the leading contributor to global disease burden, surpassing even cardiovascular diseases.

The ten conditions contributing most to neurological health loss in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer’s disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications from preterm birth, autism spectrum disorder, and nervous system cancers. Notably, diabetic neuropathy more than tripled globally since 1990, rising to 206 million cases by 2021—the fastest-growing neurological condition.

Preventable Risk Factors

Research identified 20 modifiable risk factors for neurological conditions. High systolic blood pressure and air pollution are the most significant—eliminating these could prevent up to 84% of stroke disability-adjusted life years. Reducing lead exposure could decrease idiopathic intellectual disability burden by 63.1%, while controlling fasting plasma glucose levels could reduce dementia burden by 14.6%.

Smoking significantly contributes to stroke, dementia, and multiple sclerosis risk. Physical inactivity, poor diet, and alcohol consumption also increase neurological disease risk. These findings underscore that many neurological conditions are preventable through lifestyle modifications and environmental improvements.

Age-Related Changes

While absolute numbers of people with neurological conditions increased by 18% from 1990 to 2021, age-standardized rates actually decreased. This means population growth and aging—not worsening conditions—primarily drive the increase. As global populations age, maintaining nervous system health becomes increasingly critical for individual and societal wellbeing.

Maintaining Nervous System Health

Given the nervous system’s fundamental role in every aspect of life, protecting its function deserves priority attention.

Lifestyle Factors

Physical exercise benefits nervous system health through multiple mechanisms. Aerobic activity increases blood flow to the brain, promotes new neuron formation in the hippocampus, and enhances production of brain-derived neurotrophic factor—a protein supporting neuron survival and growth. Regular exercise also improves sleep quality, which is essential for memory consolidation and cellular repair.

Nutrition directly impacts nervous system function. The brain requires constant glucose supply, B vitamins for neurotransmitter synthesis, omega-3 fatty acids for membrane structure, and antioxidants to combat oxidative stress. Mediterranean-style diets rich in vegetables, fruits, whole grains, fish, and healthy fats associate with lower dementia risk and better cognitive function across the lifespan.

Sleep and Recovery

Sleep isn’t passive downtime—it’s when your nervous system performs essential maintenance. During sleep, the glymphatic system clears metabolic waste products from the brain, including proteins that accumulate in Alzheimer’s disease. Deep sleep consolidates memories, transferring information from temporary to long-term storage.

Most adults require 7-9 hours of sleep nightly for optimal nervous system function. Chronic sleep deprivation impairs attention, decision-making, emotional regulation, and increases accident risk. It also elevates inflammation and may accelerate cognitive decline.

Injury Prevention

Traumatic brain and spinal cord injuries can permanently alter nervous system function. Wearing seatbelts, helmets during cycling or contact sports, and fall-prevention measures protect against mechanical damage. Avoiding neurotoxins—including excessive alcohol, recreational drugs, and occupational chemical exposures—prevents chemical injury to neurons.

Mental Stimulation

The nervous system demonstrates remarkable plasticity—the ability to form new connections and reorganize existing pathways throughout life. Mental challenges, learning new skills, and social engagement promote this plasticity, potentially building cognitive reserve that delays symptom onset in neurodegenerative diseases.

Activities that combine physical, cognitive, and social elements—dancing, team sports, playing musical instruments—provide particularly robust benefits. These activities engage multiple brain regions simultaneously, strengthening diverse neural networks.

Frequently Asked Questions

What happens when the nervous system doesn’t function properly?

Nervous system dysfunction produces diverse symptoms depending on the affected region. Problems with sensory pathways cause numbness, tingling, or pain. Motor pathway damage results in weakness, paralysis, or uncontrolled movements. Autonomic dysfunction affects heart rate, blood pressure, digestion, or temperature regulation. Cognitive impairments alter memory, attention, or reasoning. Many conditions affect multiple functions simultaneously.

How fast do nerve signals travel in the body?

Signal speed varies considerably based on nerve type and whether it’s myelinated. Unmyelinated nerve fibers conduct signals at 0.5-2 meters per second. Myelinated sensory and motor fibers transmit signals at 50-120 meters per second. This variation explains why you feel a sharp pain almost immediately when injured, while dull, aching pain arrives moments later—they travel different neural pathways.

Can the nervous system repair itself after damage?

The peripheral nervous system has substantial regenerative capacity. Damaged peripheral nerves can regrow at approximately 1 millimeter per day under favorable conditions, though recovery remains incomplete for severe injuries. The central nervous system, unfortunately, has very limited regeneration ability. Neurons in the brain and spinal cord rarely regenerate after damage, though surrounding neural tissue can sometimes compensate through plasticity, forming new connections to restore partial function.

Why does the nervous system require so much energy?

Maintaining electrical gradients across billions of neurons demands enormous energy. Ion pumps constantly work against concentration gradients to maintain the charge difference that enables action potentials. Neurotransmitter synthesis, vesicle recycling, and signal propagation all require ATP. Additionally, the brain maintains constant activity even at rest, with intrinsic neural circuits generating ongoing patterns independent of external input. This baseline activity plus information processing explains why the brain consumes roughly 20% of the body’s total energy despite its small size.

The nervous system represents one of biology’s most sophisticated information processing networks, coordinating trillions of cellular activities every second. Its three-pound command center manages everything from subconscious reflexes to abstract reasoning, linking our internal world with external reality through electrochemical signals traveling at speeds exceeding 100 meters per second.

Research from 2021 revealed that nervous system disorders affect nearly half the global population, causing more disability than any other disease category. This statistic, while sobering, highlights opportunities for prevention. Many neurological conditions stem from modifiable factors—blood pressure, air quality, physical activity, and metabolic health—meaning individual and societal choices significantly impact nervous system health.

Understanding how this system works changes how we care for it. The same networks that enable us to read these words benefit from the sleep we get tonight, the food we eat tomorrow, and the physical and mental challenges we embrace throughout life. Your nervous system adapts continuously, sculpted by experience and shaped by habits, making nervous system health not a fixed trait but an ongoing practice of informed choices.

Data Sources

Global Burden of Disease Study 2021 – The Lancet Neurology, March 2024
Cleveland Clinic – Nervous System Overview, December 2024
National Institute of Child Health and Human Development – Nervous System Functions
Institute for Health Metrics and Evaluation – Neurological Conditions Analysis, 2024
Queensland Brain Institute – Types of Neurons, University of Queensland
National Center for Biotechnology Information – Anatomy of Central Nervous System