Nervous system – structure, functions, the most common diseases and their diagnosis

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The human nervous system is divided into the central nervous system, which consists of the brain and spinal cord, and the peripheral nervous system, which is made up of 31 pairs of spinal nerves and 12 pairs of cranial nerves. It affects body functions such as movement, breathing and blood circulation.

What is the nervous system?

The nervous system directs almost everything we do, think, say, or feel. It controls complex processes such as movement, thought, and memory. It also plays a vital role in activities that your body does without thinking, such as breathing, blushing, and blinking.

The nervous system affects every aspect of health, including:

1. Thoughts, memory, learning and feelings.
2. Movements such as balance and coordination.
3. The senses, including the way the brain interprets what we see, hear, taste, touch and feel.
4. Sleep, healing and aging.
5. Patterns of heartbeat and breathing.
6. Reaction to stressful situations.
7. Digestion, as well as how hungry and thirsty we are.
8. Body processes like puberty.

This complex system is basically our body’s “command center”. It regulates its systems and allows you to experience the environment.

The vast network of nerves sends electrical signals to and from other cells, glands, and muscles throughout the body. These nerves pick up information from the world around us. The nerves then interpret the information and control our reaction.

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Nervous system – functions

The basic operation of the nervous system depends largely on tiny cells called neurons. The brain has billions of them and they carry out many specialized tasks. For example, sensory neurons send information from the eyes, ears, nose, tongue, and skin to the brain. Motor neurons carry messages from the brain to the rest of the body. However, all neurons transfer information to each other through a complex electrochemical process, creating connections that influence the way we think, learn, move, and behave.

Intelligence, learning and memory. As we grow up and learn, messages travel from one neuron to another over and over again, creating connections or pathways in the brain. This is why driving requires so much concentration when one learns it first, but then becomes second nature to that person: the path has been established.

The brain is very adaptive in young children. In fact, when one part of a toddler’s brain is damaged, another part can often learn to take over some of the lost functions. But as we age, the brain has to work harder to create new neural pathways, making it difficult to master new tasks or change established behavior patterns. That’s why many scientists believe it’s important to challenge your brain to learn new things and create new connections – this helps keep your brain active throughout your life.

Memory is another complex function of the brain. The things we have done, learned and seen are first processed in the cerebral cortex. Then, if we sense that this information is important enough to be remembered permanently, it is passed on to other areas of the brain (such as the hippocampus and amygdala) for long-term storage and retrieval. As these messages travel through the brain, they also create pathways that serve as the basis of memory.

Movement. Different parts of the brain move different parts of the body. The left side of the brain controls the movements of the right side of the body, and the right side controls the movements of the left side of the body. For example, when we press the gas pedal in a car with our right foot, the left hemisphere of the brain sends a message that allows us to do so.

Basic body functions. A part of the peripheral nervous system called the autonomic nervous system controls many of the body’s processes that we almost never have to think about, such as breathing, digestion, sweating, and chills. The autonomic nervous system consists of two parts: the sympathetic nervous system and the parasympathetic nervous system.

The sympathetic nervous system prepares the body for sudden stress as if we were witnessing a seizure. When something scary happens, the sympathetic nervous system makes the heart beat faster so it quickly sends blood to different parts of the body that may need it. It also causes the adrenal glands at the top of your kidneys to release adrenaline, a hormone that gives your muscles extra power to get away quickly. This process is known as the body’s “fight or flight” response.

The parasympathetic nervous system works exactly the opposite: it prepares the body to rest. It also helps to move the digestive tract so that our bodies can efficiently get nutrients from the food we eat.

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What are the parts of the nervous system?

The nervous system consists of two main parts. Each part contains billions of cells called neurons or nerve cells. These special cells send and receive electrical signals through our body to tell it what to do.

The main parts of the nervous system are the central and peripheral nervous systems.

Central nervous system: This is made up of the brain and spinal cord. Our brain uses nerves to send messages to the rest of the body. Each nerve has a protective outer layer called the sheath or myelin sheath. This myelin sheath insulates the nerves and helps transmit messages.

Peripheral Nervous System: The peripheral nervous system is made up of many nerves that branch from the central nervous system throughout the body. This system transmits information from the brain and spinal cord to the organs, arms, legs, fingers and toes. The peripheral nervous system includes:

1. the somatic nervous system that directs conscious movements that depend on our will.
2. an autonomic nervous system that controls the things we do without thinking about them.

Structure of the central nervous system

The central nervous system (CNS or CNS) is made up of the so-called gray matter (external) and white matter (internal). The gray matter consists of nerve cells, while the white matter – axons (nerve fibers).

The structures of the CNS include:

1. the brain (the brain proper, dumbrain and the brainstem, which consists of the midbrain, the bridge and the medulla),
2. spinal cord.

The brain is the main site for receiving and processing information both outside and inside the body. The protection of the organ is provided by the bones of the skull. In addition to them, it is also surrounded by three meninges: the dura mater, arachnoid, and the dura mater, filled with cerebrospinal fluid. The blood-brain barrier (the characteristic structure and function of the blood vessels surrounding the brain) is another element of protection, thanks to which only certain substances are permeable.

The brain consists of three main parts: the forebrain, midbrain, and hindbrain.

Forebrain

The forebrain is the largest and most complex part of the brain. It consists of the brain, an area with all the folds and grooves typical of brain images, as well as several other structures beneath it. The brain contains information that basically makes us who we are: our intelligence, memory, personality, emotions, speech, and our ability to feel and move. Certain areas of the brain process these different types of information. They are called lobes, and there are four of them: frontal, parietal, temporal and occipital.

The brain consists of two hemispheres separated by a longitudinal fissure. The connection between them is provided by nerve fibers located in the great commissural. The surface of the brain is strongly folded, which significantly increases its surface area and the number of nerve cells. The outer part is made of gray matter, while the inner part is white matter.

These halves may look like mirror images of themselves, but many scientists believe that they perform different functions:

1. The left side is considered to be the logical, analytical, objective side.
2. The right side is considered more intuitive, creative and subjective.

Therefore, when it does various math calculations, we use the left side. On the other hand, when we listen to music, we use the right side. Some people are believed to be more “right hemisphere” or “left hemisphere” while others are more “whole brain”, meaning that they use both halves of their brain to the same extent. The outer layer of the brain is called the cortex. The information gathered by the five senses travels to the brain, to the cortex. This information is then directed to other parts of the nervous system for further processing. For example, when we touch something hot, not only is there a message to move the hand, but the information also goes to another part of the brain to help us remember not to do it again.

In the inner forebrain are the thalamus, hypothalamus and pituitary gland:

1. the thalamus carries information from the sense organs such as the eyes, ears, nose and fingers to the cortex;
2. the hypothalamus controls pulse, thirst, appetite, sleep patterns, and other processes in our body that occur automatically;
3. The hypothalamus also controls the pituitary gland, which produces hormones that control growth, metabolism, water and mineral balance, sexual maturity and the stress response.

Midbrain

The midbrain, under the middle of the forebrain, acts as the primary coordinator of all messages going in and out of the brain to the spinal cord.

Backbrain

The backbone is located under the back end of the brain. It consists of the cerebellum, the bridge and the core. The cerebellum, also known as the “little brain” because it looks like a small version of the brain, is responsible for balance, movement and coordination.

The bridge and core, along with the midbrain, are often called the brainstem. The brain stem receives, sends and coordinates brain messages. It also controls many of the body’s automatic functions, such as breathing, heart rate, blood pressure, swallowing, digesting, and blinking.

The second major structure of the central nervous system is the spinal cord, which is primarily responsible for transmitting information from the brain to the peripheral system and vice versa. The core, like the brain, protects the bones (the so-called spinal canal), as well as the meninges and the cerebrospinal fluid. At the center of the spinal cord is the middle canal, filled with cerebrospinal fluid, which acts as an extension of the ventricles of the brain. Contrary to the brain, in the spinal cord it is the white matter that surrounds the gray matter. The white matter of the spinal cord consists of axons that send signals from the brain and vice versa, otherwise known as cords.

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Structure of the peripheral nervous system

The peripheral nervous system (PNS) includes all the nerves that branch out of the brain and spinal cord and extend to other parts of the body, including muscles and organs. The primary role of the PNS is to connect the CNS with organs, limbs, and skin. These nerves extend from the central nervous system to the outermost areas of the body. The nerves that make up the peripheral nervous system are actually axons or bundles of axons from nerve cells or neurons. In some cases, these nerves are very small, but some nerve bundles are so large that they are easily visible to the human eye.

The peripheral nervous system itself is divided into two parts: the somatic nervous system and the autonomic nervous system. Each of these elements plays a key role in the functioning of the peripheral nervous system.

Somatic nervous system

The somatic system is the part of the peripheral nervous system responsible for carrying sensory and motor information to and from the central nervous system. The somatic nervous system takes its name from the Greek word soma, which means “body”. The somatic system is responsible for the transmission of sensory information, as well as for voluntary movement. This system includes two main types of neurons:

1. motor neurons: they carry information from the brain and spinal cord to muscle fibers throughout the body. These motor neurons allow us to take physical actions in response to stimuli from the environment.
2. sensory neurons: they carry information from the nerves to the central nervous system. It is these sensory neurons that allow us to pick up sensory information and send it to the brain and spinal cord.

Autonomous nervous system

The autonomic system is the part of the peripheral nervous system that regulates involuntary bodily functions such as blood flow, heartbeat, digestion, and breathing. In other words, it is the autonomic system that controls those aspects of the body that are not normally under voluntary control. This system enables the implementation of these functions without the need to consciously think about their existence. The autonomous system is further divided into two branches:

1. parasympathetic system: helps to maintain normal body functions and conserves physical resources. Once the threat is over, this system slows down your heart rate, slows your breathing, reduces blood flow to the muscles, and constricts the pupils. This allows us to bring our bodies back to a normal resting state.
2. sympathetic nervous system: By regulating the flight or fight response, the sympathetic nervous system prepares the body to use energy in response to environmental threats. When action is needed, the sympathetic nervous system triggers a response, increasing the heart rate, increasing the rate of breathing, increasing blood flow to the muscles, activating sweat and dilating the pupils.

Going back to the nerves that make up the peripheral nervous system, several types can be mentioned.

1. Spinal nerves

Spinal nerves are responsible for transmitting information from muscles, organs, and glands to the spinal cord. There are 31 spinal nerves that branch into different areas of the body from the spinal cord.

1. Cranial nerves

The cranial nerves are responsible for the receptors around the head and neck. Instead of connecting to the spinal cord, these nerves travel directly to the brain. There are 12 pairs of cranial nerves that transmit motor and sensory information from areas such as the face, mouth, eyes, nose, and ears.

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Nervous system – diagnostics

There are a number of tests and procedures to diagnose conditions related to the nervous system. In addition to traditional x-rays, a specialized x-ray called fluoroscopy examines the body in motion, such as blood flowing through arteries.

Other standard neurological tests include MRI (magnetic resonance imaging), computed tomography, and an electroencephalogram (EEG), which records the continuous electrical activity of the brain. Positron emission tomography (PET) is a procedure that measures the metabolism of cells or tissues and brain activity to detect tumors or diseased tissue.

A lumbar puncture (lumbar puncture), on the other hand, involves inserting a needle into the spinal canal to drain a small amount of cerebrospinal fluid that is examined for infection or other abnormalities.

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The human nervous system – the most common diseases

The list of diseases related to the nervous system is long, and given the fact, their symptoms can be very diverse. Therefore, you should carefully watch your body.

Thousands of disorders and conditions can affect the nerves. A damaged nerve has trouble sending a message. Sometimes it is so damaged that it cannot send or receive messages at all. A nerve injury can cause numbness, tingling, or pain. It may be difficult or impossible for an injured area to move.

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

Disease. Many infections, cancers and autoimmune diseases can cause problems with the nervous system, the most common of which are:

1. Parkinson’s disease

The basal ganglia is located deep in the brain, in an area responsible for controlling movement. These nerves produce a compound known as dopamine, which is important in coordinating many functions, including executive function and motor control. Although the cause is not yet clear, sometimes the basal ganglia can become damaged and begin to die. Parkinson’s disease is the result, as the loss of dopamine gradually hinders key functions such as walking, speaking, and memory recall. These effects are compounded by the loss of the nerves responsible for producing norepinephrine, a key compound in the sympathetic nervous system needed to regulate heart rate and blood pressure. According to the National Institute of Aging, drugs that increase the amount of dopamine in the brain can help fight the symptoms of the disease.

1. Facial nerve palsy

The main nerves spread outward from the central nervous system to various organs and tissues, each of which supports specific functions. The VII cranial nerve is known as the facial nerve because it controls many of the muscles in our face, including blinking and smiling. When this nerve is inflamed, damaged, or otherwise disturbed, paralysis of the facial nerve, also known as Bell’s palsy, can develop, which involves weakness or paralysis of the facial muscles, according to the National Institute of Neurological Disorders and Stroke. Usually only one side of the face is affected, causing symptoms such as drooping mouth on one side and loss of eyelid control. The full symptoms of Bell’s palsy are often temporary, with the affected areas recovering partially or completely within six months. While it’s not always clear what causes cranial nerve swelling and Bell’s palsy, scientists believe that a recurrent viral infection of the nervous system triggers an immune response that causes nerve damage.

1. Multiple sclerosis

Neurons are signaling agents in our bodies, but they don’t function by themselves. The axons that carry signals from the body of the neuron’s cell are covered with myelin sheaths. According to the National Multiple Sclerosis Society, they are produced in the central nervous system by cells called oligodendrocytes, allowing the myelin sheaths to protect and facilitate nerve conduction. In multiple sclerosis, an abnormal immune response in the central nervous system removes the myelin sheath and causes much scarring of the nerves (sclerosis) from which the disease originated. Research is ongoing to treat the disease by encouraging regeneration of the myelin sheaths.

1. Peripheral neuropathy

While several neurodegenerative diseases affect the central nervous system mainly or exclusively, there are a number of diseases that affect the peripheral nervous system. Together, these diseases are referred to as peripheral neuropathies. As the affected area is the peripheral nervous system, such neuropathies lead to loss of sensation and regulatory control of the limbs. According to the University of Michigan Health, these include loss of coordination and sensation in the fingers and toes, and imbalance. The causes of peripheral neuropathy have not yet been fully elucidated, but scientists have determined that one of the main causes is diabetes, which causes prolonged periods of high blood sugar.

1. Stroke

A stroke occurs when one of the brain’s blood vessels becomes blocked or suddenly ruptures. Without enough blood, part of the brain dies. Then he cannot send messages with his nerves. A stroke can damage the nerves, ranging from mild to severe.

1. Accidental injuries

Nerves can be crushed, stretched or cut in an accident. Car accidents and falls are common injuries that can damage nerves anywhere in the body.

1. Pressure

If a nerve is compressed, it cannot get enough blood to do its job. Nerves can be pinched or trapped for a number of reasons, such as overstrain (as in carpal tunnel syndrome), a tumor, or structural problems such as sciatica.

1. Toxic substances

Chemotherapy drugs, narcotics, alcohol abuse, and poisonous substances can cause peripheral neuropathy or nerve damage. People with kidney disease are at a higher risk of nerve damage because their kidneys have difficulty filtering out toxins.

1. Getting older

As we age, neuron signals may not travel as fast as they used to. You may feel weaker and our reflexes may slow down. Some people lose feeling in the fingers, toes, or other parts of the body.

Symptoms of nervous system disorders

The most common general signs and symptoms of nervous system disorders are listed below. However, everyone can experience nervous system symptoms in different ways.

The most common symptoms include:

1. headaches and dizziness,
2. loss of consciousness or fainting
3. muscle cramps
4. muscle weakness or loss
5. blindness or double vision
6. back pain which spreads to the feet, toes or other parts of the body
7. delirium and dullness
8. tremors and convulsions,
9. paresis and paralysis (paralysis),
10. motor coordination disorders,
11. speech disorders or impaired motor coordination,
12. memory impairment.

Naturally, not all of them have to be associated with diseases of the nervous system. Sometimes they are caused by diseases of other organs or deficiencies of certain nutrients, so it is worth consulting a doctor in the case of recurring ailments.

Specialists dealing with the treatment of disorders of the nervous system

The best way to deal with disorders of the nervous system is to help doctors. We don’t always need every type of specialist, but it is good to know who these specialists are and how they can help. Here is a list of some doctors who may be involved in treating nervous system disorders.

1. Neurologist. Doctors who diagnose and treat disorders of the nervous system are called neurologists. Some neurologists treat acute strokes and brain aneurysms with endovascular techniques.
2. Neurosurgeon. Surgeons who act as a treatment team for nervous system disorders are called neurological surgeons or neurosurgeons.
3. Neuroradiologist and interventional radiologist. He is a radiologist who specializes in diagnosing nervous system disorders through imaging and in treating nervous system conditions such as brain aneurysms, acute strokes and vertebral fractures.
4. Psychologist. Emotional problems such as anxiety, depression, mood swings, and irritability are common in disorders of the nervous system. Psychologists can run tests to find out how much our disorder affects the way we think and feel. Psychologists also conduct talk therapy to help us deal with the emotional effects caused by disorders of the nervous system.
5. Psychiatrist. Like a psychologist, this specialist deals with emotional and behavioral symptoms caused by disorders of the nervous system. In most cases, talk therapy works best for these problems. However, if a patient needs medications to treat symptoms such as depression or anxiety, this doctor can help.
6. Physiotherapist. It is a movement specialist who can help us move and walk well. In physiotherapy, you can also work on painful or stiff muscles and joints.
7. Occupational therapist. This specialist helps you learn to cope with everyday activities. You may have problems with carrying out tasks that must be performed at work or at home. An occupational therapist will help you find ways to adapt to any changes in our physical abilities.
8. Speech therapist. A speech therapist specializes in communication, including cognitive communication. It also diagnoses and treats swallowing problems.

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How to take care of the nervous system?

The nervous system is our body’s command center. It requires care to run properly. The brain needs sleep to rest and regenerate, so a good, regular sleep schedule is key. It is also important to eat a healthy balanced diet that includes foods rich in omega-3 fatty acids. These include oily fish such as salmon, albacore tuna, mackerel, herring, and trout.

Stress can also affect the nervous system, but there are a few things you can do to deal with it:

1. Exercise regularly,
2. take breaks
3. spend time with family and friends
4. meditate or practice yoga.

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The best way to avoid nerve damage from disease is to deal with conditions that can damage the nerves, such as diabetes.

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