The Nervous System

There are over 7 trillion nerves in the human body! Some people are capable of getting on every last damn one of them!

Autonomic Nervous System

The autonomic nervous system (ANS) is essential for survival and responsible for the body’s involuntary activities such as cardiovascular, gastrointestinal, and thermoregulatory homeostasis. The ANS is divided into two major branches: the sympathetic nervous system (SNS), which controls the “fight or flight” responses, and the parasympathetic nervous system (PNS), which oversees the body’s maintenance functions, including digestion. Both disease states and the stress of surgery can lead to changes in the ANS, potentially deleterious effects. Thus, a primary goal of anesthetic management is to modulate the body’s autonomic responses. Contemporary anesthesia providers have access to many pharmacologic drugs that can profoundly alter autonomic activity; thus, a thorough understanding of the anatomy and physiology of the ANS is essential.

What is the 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 your body’s actions without thinking, such as breathing, blushing, and blinking.

Your nervous system affects every aspect of your health, including your:

Thoughts, memory, learning, and feelings.
Movements, such as balance and coordination.
Senses, including how your brain interprets what you see, hear, taste, touch, and feel.
Sleep, healing, and aging.
Heartbeat and breathing patterns.
Response to stressful situations.
Digestion, as well as how hungry and thirsty you feel.
Body processes, such as puberty.

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.

FUNCTION

What does the nervous system do?

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 your body’s actions automatically, like breathing, shivering, having a regular heartbeat, and digesting food.

ANATOMY

What are the parts of the nervous system?

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:

The Somatic Nervous System guides your voluntary movements.
The Autonomic Nervous System controls the activities you do without thinking about them.

CONDITIONS AND DISORDERS

What conditions and disorders affect the nervous system?

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 to the injured area.

Nerve damage can happen in several ways. Some of the most common causes of nerve damage include:

Disease: Many infections, cancers, and autoimmune diseases like diabetes, lupus, and rheumatoid arthritis can cause nervous system problems. Diabetes can lead to diabetes-related neuropathy, causing tingling and pain in the legs and feet. A condition called multiple sclerosis attacks the myelin around nerves in the CNS.
Stroke: A stroke happens when one of the brain’s blood vessels becomes blocked or suddenly bursts. Without enough blood, part of the brain dies. Then it can’t send messages via nerves. A stroke can cause nerve damage ranging from mild to severe.
Accidental injury: Nerves can be crushed, stretched, or cut in an accident. Car crashes and falls are common injuries that can damage nerves anywhere in your body.
Pressure: If a nerve is pinched or compressed, it can’t get enough blood to do its job. Nerves can be pinched or trapped for many reasons, such as overuse (as in carpal tunnel syndrome), tumors, or structural problems like sciatica.
Toxic substances: Chemotherapy medicines, illegal drugs, excessive alcohol, and poisonous substances can cause peripheral neuropathy or nerve damage. People with kidney disease are more likely to develop nerve damage because their kidneys have difficulty filtering out toxins.
Aging process: As you age, your neurons’ signals may not travel as fast as they used to. You may feel weaker, and your reflexes may slow down. Some people lose sensation in their fingers, toes, or other body parts.

How common are these conditions?

Some causes of nerve damage occur more frequently than others. They include:

Diabetes: This disorder of the endocrine system causes nerve damage called diabetes-related neuropathy. Around 30 million Americans have diabetes, and nearly 50% of them have some nerve damage. Neuropathy of diabetes usually affects the arms, legs, hands, feet, fingers, and toes.
Lupus: About 1.5 million Americans live with lupus, and 15% of them have experienced nerve damage.
Rheumatoid arthritis: People with rheumatoid arthritis can also develop neuropathy. Rheumatoid arthritis affects more than 1.3 million people in the U.S. It’s one of the most common forms of arthritis.
Stroke: Around 800,000 Americans have a stroke every year. Strokes occur more often in people over age 65.

CARE

How do I keep my nervous system healthy?

Your nervous system is the command center for your entire body. It needs the 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 prevent nerve damage from disease is to manage conditions that can injure your nerves, such as diabetes.

FREQUENTLY ASKED QUESTIONS

When should I call my doctor?

Call your doctor immediately 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: