Nervous System: Function, Parts, and Main Organs

Nervous System: Function, Parts, and Main Organs

Home breadcrumb Blog breadcrumb Health breadcrumb Organs & Systems breadcrumb Nervous System breadcrumb Nervous System: Function, Parts, and Main Organs

cover image
2.5.2025 0 comments

Author: Trisha Houghton, CNS, ASIST

The human nervous system is one of the most important—and the most complex—of the internal systems.

It’s made up of hundreds of thousands of kilometers of nerve cells (150,000  180,000 [1]) that serve an immensely crucial role in keeping your body running.

In this blog post, we’ll take a deep dive into this critical system. We’ll look at the various parts of the nervous system, which organs get involved in nervous system function, and how it works on a cellular level. We’ll also explore common disorders that impair nervous system function.

By the end, you’ll know everything you need to know to keep this vital system healthy and operating at optimal capacity.

Introduction to the Nervous System

Let’s start with the basics: what the nervous system is and what it does.

The nervous system is made up of three primary components: 

  • Your brain;
  • Your spinal cord;
  • Your nerves.

The human brain sends electrical signals through the spinal cord and nerves to control every body function. These signals regulate your heartbeat, intestinal muscle contractions for digestion, hormone production, and pupil dilation.

Literally everything in your body is controlled by your nervous system, making it one of the most crucial systems for moving, sensing, and just existing.

Primary Functions of the Nervous System

The main functions of the nervous system can be boiled down to five categories.

Cognitive Function

Your brain is your “thinking box”. All the neural activity in your brain enables thought, memory, emotion, and decision-making, which then controls every other aspect of your existence.

It processes information from your environment, allowing you to learn, solve problems, and adapt to new situations. This constant activity shapes your personality, behaviors, and how you interact with the world.

Sensory Input 

The nerves in your body collect sensory input—such as light, sound, smell, heat, cold, and pain—and transmit it to the brain. This information travels as an electrical signal through the nerves and allows rapid communication within the body.

The brain processes these signals and triggers a physiological response. This process is a fundamental part of how the nervous system works to maintain balance and react to the environment.

Integration

The brain is responsible for processing and interpreting sensory input.

For example, you don’t directly feel “pain.” Instead, your nerves detect potentially harmful stimuli, such as heat, and send electrical signals to your brain. Your brain then interprets these signals as pain.

The nervous system also makes decisions based on that sensory input—for example, to move away from a painful stimulus or toward a pleasant one.

Motor Output 

The nervous system sends signals (nerve impulses) from the brain and spinal cord to muscles, organs, and glands. These glands include the pituitary gland, sweat glands, and adrenal glands. This process allows the body to respond to stimuli.

For example, moving away from danger involves a complex interplay of muscles and activates certain hormones from your endocrine system (cortisol and adrenaline, your “fight or flight” response).

Homeostasis 

The nervous system is also responsible for monitoring internal conditions and regulating body functions to maintain homeostasis. It works closely with most internal organs to ensure stable internal environments, such as temperature and pH balance.

Additionally, the major divisions of the nervous system—the central and peripheral nervous systems—coordinate responses to both internal and external stimuli to keep the body in balance.

Main Divisions of the Nervous System

a person with a healthy Nervous System takes a walk outdoors

The nervous system can be broken down into two “parts”: the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Your PNS is responsible for monitoring your body in order to detect any sign of damage, instability, or change that needs correcting. It sends signals up the chain to your CNS, and transports signals from your CNS to the rest of your body to trigger whatever function the CNS needs triggered.

Your CNS is responsible for processing and integrating the information it receives from the PNS. It also controls thought, emotions, and decision-making, as well as initiating and controlling movement.

Main Parts of the Central Nervous System

The central nervous system is made up of your brain and your spinal cord.

The Brain 

The brain can be broken down into individual parts, of which there are many:

  • The cerebellum is located at the back of the brain. It facilitates limb coordination, voluntary motor actions, and processing information from the brain to control movement.
  • The frontal lobe contains the motor cortex (necessary for precise movement) and Broca area (necessary for production language). The frontal lobe facilitates problem-solving, memory, voluntary motor function, attention, and language. It is responsible for governing emotional regulation, decision-making, and personality traits.
  • The parietal lobe processes sensory information in order to register what is being “touched”.
  • The occipital lobe contains the visual cortex and is involved in processing visual stimuli.
  • The temporal lobe processes auditory stimuli and plays a role in speech comprehension.
  • The basal ganglia play a role in coordination and both voluntary and involuntary movements of the muscles.
  • The thalamus detects sensory signals sent from the body and processes it to be distributed to the rest of the brain appropriately. This part of the brain also plays a role in sleep and consciousness.
  • The hypothalamus maintains homeostasis by regulating everything from appetite and thirst to blood pressure, hormones to internal temperature.
  • The medulla oblongata (a part of the brain called the brain stem sometimes) connects the spinal cord to the brain, and which plays a role in monitoring your respiratory system as well as regulating cardiovascular function.
  • The limbic system, made up of many smaller brain structures, controls motivation, memory, and emotion, as well as olfactory responses, emotional stress, pleasure, addiction, and emotional processing.

While there are many more brain structures, these are the ones most critical for central nervous system function.

Your brain is surrounded by cerebrospinal fluid, a colorless liquid that provides some truly important functions, including support and nutrition, maintaining homeostasis, and acting as a shock absorber to protect against impact.

The Spinal Cord 

a women gets her spinal cord checked where nerves branch

The spinal cord is a thick column of highly sensitive spinal nerve tissue that runs through the vertebral column. The vertebral column acts as a protective sheath of sturdy bone. The spinal cord also branches out to the smaller nerves of the peripheral nervous system.

The spinal nerves form the neural connections between the “thinking box” of your brain and the nerves that will actually trigger whatever response your brain is indicating is necessary in your limbs. It relays the electrical signals between your brain and peripheral nerves.

Your spinal cord is also surrounded by cerebrospinal fluid.

Main Parts of the Peripheral Nervous System

The Peripheral Nervous System is made up of a highly intricate network of nerve tissue that runs through your entire body.

It can be broken down into two systems: the somatic nervous system and the autonomic nervous system.

The Somatic Nervous System 

The somatic nervous system is made up of motor and sensory nerves.

Its function is to relay sensory information from every part of your body—your ears, eyes, skin, muscles, etc.—and send it to your brain for processing.

The somatic nervous system also plays a role in voluntary movement. It responds when your brain sends signals and causes muscles to either contract or relax according to your brain’s direction.

a person with a healthy nervous system

The Autonomic Nervous System 

The autonomic nervous system is responsible for working with the brain to regulate involuntary functions. It controls functions like your heartbeat, digestion, hormone production, saliva production, dilation of your pupils, perspiration, and countless more.

The autonomic nervous system can be further divided into two smaller systems: the sympathetic nervous system, which activates your internal “fight or flight” responses; and the parasympathetic nervous system, which activates your internal “rest and digest” responses.

How the Nervous System Works

Now that we understand what the nervous system is, it’s time to take a closer look at how it works.

Let’s be clear: this is an incredibly complex subject that would take far more time and space than we have to dedicate to it. For the sake of brevity, we are simplifying it as much as possible to be easily comprehended.

There are two types of nervous tissue:

  • Neurons, which facilitate nerve conduction and sending messages throughout the body, from the brain down to the nerves branching out and back again.
  • Glial cells, which support neurons and bind them together. They also occasionally provide immune support.

The smallest and most basic unit in your nervous system—which makes up the majority of your nervous system, really—is the neuron, or nerve cell.

Neurons are comprised of:

  • The cell nucleus, the core of the cell body that enables it to perform the function for which it was created.
  • Dendrites, finger-like projections that facilitate communication between cells.
  • Axons, long fibers coated in a membrane (called the myelin sheath) that contain bumps.

Each bump on the myelin-sheathed axon sits near dendrites from other neurons. The myelin sheath insulates axons, speeding up the transmission of electrical signals and ensuring efficient nerve conduction. Electrical signals pass between the empty space (synapses) between the dendrites and axons (relayed via neurotransmitters) and continue up the chain of nerves (made up of nerve cells) to relay messages to and from the brain.

Glial cells typically lack the dendrites and axons common to neurons.

There are three types of nerve cells in the body:

  • Sensory neurons, which register information (via sensory receptors) from your senses in response to external stimuli (such as sensory input or pain signals) and send electrical signals from neuron to neuron up the spinal cord to be processed in the brain for the appropriate response.
  • Motor neurons, which transport electrical motor signals that form in the brain (instigating movement or some voluntary movement) down the spinal cord and to the peripheral nervous system to be translated by your muscles as movement.
  • Interneurons, which communicate between your motor and sensory neurons.

One very important aspect of your nervous system we need to discuss is your withdrawal response, aka. your reflexes. A reflex is the involuntary action by way of the reflex arc, the neural pathway the nerve travels through which allows for the reflex response.

This is an automatic response that bypasses the brain—it takes place in your spinal cord. When your nervous system senses danger, such as excessive heat or an incoming threat, it activates spinal motor neurons to facilitate movement in the body to avoid that threat.

The brain is eliminated from the equation because waiting for sensory information to travel up the spinal cord would slow down response time. The process of receiving and processing this information in the brain, then sending the appropriate responses back down the spinal cord to the correct muscles, takes too long. Bypassing the brain allows for faster, more immediate reactions.

Because this response is controlled in the spinal cord, it ensures the fastest possible reaction time, thereby increasing the likelihood of avoiding damage.

Common Nervous System Disorders

Now that we know how the nervous system functions, let’s take a look at a few of the common disorders and diseases that result from dysfunction in our nervous systems.

Alzheimer’s Disease

Alzheimer’s disease is a progressive degeneration of brain function that impairs memory, cognition, and even motor function.

This condition is caused by the buildup of amyloid plaques around the brain, as well as neurofibrillary tangles, both of which can impair the effective transmission of electrical signals through the brain.

Over time, the brain cells die off and brain shrinkage occurs, leading to decreased cognitive function.

Parkinson’s Disease

Parkinson’s disease is a condition that affects movement due to degeneration of neurons in the brain. 

As neurons break down in the brain, less dopamine is produced, leading to irregular brain activity—including muscle rigidity, slowed movement, poor posture, even loss of automatic movements.

It could be caused either by genetics or by toxins and environmental hazards, or a combination of both, that accelerate the breakdown of neurons.

Multiple Sclerosis (MS)

Multiple sclerosis is an autoimmune disease in which the body attacks the myelin sheath protecting the nerve fibers, leading to the formation of scar tissue (sclerosis) on the axons.

This buildup of scar tissue can decrease the conduction of electrical signals through the nervous system, affecting everything from coordination to muscle strength, speech to mood, memory to focus.

In addition to being an autoimmune condition, it may also be caused by genetic factors, environmental factors, or as a result of viral infections.

Epilepsy

Epilepsy, also called “seizure disorder”, is a condition characterized by recurring seizures.

Typically, the seizures are the result of abnormal electrical activity in the brain.

There is no identifiable cause of nearly half of epilepsy cases. In the other half, possible causes include genetic factors, head trauma, brain tumors, malformed blood vessels, stroke, prenatal injury, infections (like HIV or meningitis), or developmental issues.

Peripheral Neuropathy

Peripheral neuropathy is another name for nerve damage, specifically to the nerves in the peripheral nervous system (outside your spinal cord and brain).

Damage to these nerves can lead to pain, numbness, and weakness, typically in the hands or feet.

The nerve damage can be caused by diabetes, metabolic syndrome, autoimmune disease, infection, tumors, bone marrow disorders, kidney disease, liver disease, excessive alcohol use, injuries, or a lack of B vitamins, among other factors.

Stroke

A stroke is the result of a disruption of blood flow to the brain. Strokes can be ischemic, due to a blood clot blocking blood flow, or hemorrhagic, caused by bleeding in the brain.

The lack of oxygen causes brain cells to die off. Those dead neurons can cause loss of function in the affected brain structures and areas. Depending on the location of the stroke (a right or left hemisphere stroke), side effects may range from slurred speech to impaired vision, muscle weakness to memory loss.

Stroke risk can be elevated by factors like high cholesterol, high blood pressure, diabetes, atrial fibrillation, overuse of blood thinners, and head trauma, among other factors.

Maintaining Nervous System Health

Now that you know what can negatively affect your nervous system and decrease its function, it’s time we looked at how to positively affect and improve nervous system function:

A Balanced Diet

Nutrients like Omega-3 fatty acids, proteins, antioxidants, and B vitamins all play a significant role in maintaining a healthy brain and protecting the function and structure of your neurons.

Limit your intake of hydrogenated oils and trans fats that could elevate stroke risk or raise your cholesterol (cholesterol contributes to the formation of amyloid plaques in the brain, leading to Alzheimer’s.)

Regular Exercise

Exercise keeps your brain healthy by improving circulation, balancing neurochemicals and hormones, and ramping up electrical signals to maintain efficient communication through your entire nervous system.

It can also eliminate the fat that could contribute to strokes and the cholesterol that could lead to Alzheimer’s.

Exercise reduces your risk of all nervous system disorders and supports healthy cognitive function.

Mental Stimulation

Keeping your brain active is vital for improving memory and supporting overall brain health.

  • Here is what to consider:
  • Do activities that keep your brain active and improve your memory.
  • Do crossword puzzles, jigsaw puzzles, Sudoku, and brain teasers.
  • Learn a new skill or language.
  • Read more.
  • Play cards and complex games.

The more active you keep your brain, the more efficiently it will run your nervous system. So, introducing some brain and memory care activities in your lifestyle is always a good idea.

Get Adequate Sleep

Sleep is crucial for cognition, consolidating memories and facilitating the absorption and storage of information. It’s also believed to clear out abnormal proteins and protect nerve cell function.

The ideal is 6-8 hours of sleep (it varies from person to person) to maintain good brain health and give your nervous system a chance to repair and build new nerve cells overnight.

Manage Your Stress

Stress will elevate your blood pressure and impair nervous system function. Stress can lead to Nervous System Dysregulation (NSD) caused by an overly active “fight or flight” stress response. This dysregulation is compounded by toxins, GMOs, health, social media scrolling, and hustle culture. This will decrease the effectiveness of other internal functions.

Relaxation and stress-relieving exercises like deep breathing, meditation, Yoga, and spending time outdoors amidst natural life will reduce stress and protect nervous system function.

Avoid Toxins

Alcohol and drugs can both damage your nerve and brain cells, elevating your risk factor for disease as well as decreasing nervous system function.

Toxins in the environment (such as pollution, heavy metals, potent chemicals, etc.) can also cause nerve damage and impair brain health.

Avoiding these toxins will be a highly efficient means of protecting one of your body’s most important systems.

If you need an additional sleep booster, check out our premium sleep supplement. Restore Sleep formula is the only formula of its kind on the market that combines the 7 most powerful forms of chelated magnesium as well as includes two additional nutrients, including L-Theanine, that boost the effectiveness of this supplement to help achieve deep restorative sleep, enhance cognitive function and improve the relaxation response. 

Restore Sleep

Click here to learn more about Restore Sleep and how it can change your life for the better through providing your body with the best magnesium complex to improve your brain function, sleep quality and relaxation response. 

a woman taking care of her nervous system health

Conclusion

Wow, what a fascinatingly complex—and insanely important—system!

The nervous system controls so many important functions in our bodies: coordination, movement, thought, stimuli processing, even maintaining homeostasis. It’s crucial for keeping our bodies operating, from our organs to our skeletal muscles to our glands.

Living a balanced, healthy lifestyle using the tips we shared about is the key to sustaining our nervous system for many years of active living.

FAQs

How to tell if your nervous system is out of whack?

If your nervous system is out of whack, you will likely experience symptoms such as headaches, loss of feeling, tingling, weakness, muscle strength loss, impaired mental abilities, mood changes, memory loss, and lack of coordination.

What vitamins are good for the nervous system? 

B vitamins—specifically B1, B6, and B12—are crucial for the maintenance of nerve cells. A deficiency in these vitamins may lead to nervous system problems.

What drink is good for the nervous system?

Green and black tea, turmeric tea, coffee, kombucha, and berry juice all contain antioxidants that stimulate the brain and eradicate free radicals and reactive oxygen species that could impair cognition.

What is the neural tube?

The neural tube is an embryonic structure that develops into the brain and spinal cord, forming the foundation of the central nervous system. As the spinal cord develops, it becomes enclosed and protected by the spinal column.

How does the nervous system develop in the early stages of life?

The development of the nervous system begins with the formation of the neural plate, a flat layer of cells in the embryo. This plate folds inward to create the neural groove, which deepens as the edges rise to form the neural folds. These folds eventually fuse to form the neural tube, which develops into the brain and spinal cord. As the nervous system matures, afferent neurons emerge to carry sensory information from the body to the brain and spinal cord for processing.

How does the nervous system work to transmit information?

The nervous system transmits signals through neurons, with nerves branching from the spinal cord to the body. Sensory signals pass through the dorsal root ganglia to the brain. Ion channels allow electrical signals to travel along neurons, while many synapses enable communication between neurons for proper body function.

Resources

Anatomy, Central Nervous System

Nervous system

What are the parts of the nervous system?

Introduction to the Nervous System

Nervous system

Visual Guide to Your Nervous System

“Ouch, that hurts!” The science of pain

Alzheimers disease

Parkinsons disease

Multiple Sclerosis (MS)

Epilepsy

Peripheral neuropathy

About Stroke

zonia

We created ZONIA because we believe that everyone deserves to be empowered with the education and tools to be healthy and happy. Zonia's original videos and personalized transformation programs by our health & wellness experts will help you achieve this mission. Click on the button below to get started today: