Exploring The Nervous System

The Nervous System is the body’s internal communication system. These sensory cues are interpreted by the brain to understand what is going on outside and inside the body. Without the Nervous System, we would never understand what’s going on.

Introduction

Your nervous system serves as the command center for your body. It is controlled by your brain and governs your emotions, thoughts, and automatic responses to the environment around you. Almost all of what you think, feel, say, and do is controlled by your nervous system. It manages complex functions like memory, cognition, and movement. Furthermore, it is crucial for bodily functions like breathing, blushing, and blinking that occur automatically. It regulates other bodily functions and systems, including digestion, breathing, and sexual development (puberty). Your nervous system can be harmed by diseases, accidents, pollutants, and the natural aging process. The nervous system is split into two parts. Each component comprises billions of neurons, also known as nerve cells. These unique cells communicate with your body by sending and receiving electrical impulses. The main divisions of the Nervous System are the Central Nervous System (CNS), and the Peripheral nervous system, which then is further organized into other systems. (1)

What does the Nervous System do?

A nerve cell, or neuron, is the basic unit of the neurological system. The human brain has about 100 billion neurons. A neuron has a cell body, which contains the nucleus, as well as unique extensions known as axons (pronounced AK-sonz) and dendrites (pronounced DEN-drahytz). Nerves are bundles of axons found throughout the body. Neurons can interact across extended distances thanks to axons and dendrites. (2). When a neuron transmits a message to another neuron, it sends an electrical signal down the length of its axon. At the end of the axon, the electrical signal changes into a chemical signal. The chemical signal is then released by the axon via chemical messengers known as neurotransmitters (pronounced noor-oh-TRANS-mit-erz) into the synapse (pronounced SIN-aps)—the gap between the end of an axon and the tip of a dendrite from another neuron. The neurotransmitters carry the signal across the synapse to the adjoining dendrite, where it is converted back into an electrical signal. The electrical signal is subsequently transmitted across the neuron and through the same conversion steps as it travels to neighboring neurons.

The nervous system also consists of glia, or non-neurons, cells (pronounced GLEE-uh). Glial cells provide a variety of critical activities that keep the nervous system running smoothly. To send impulses or messages throughout your body, the nervous system employs neurons. These electrical signals go through your body, connecting your brain, skin, organs, glands, and muscles. The messages assist you in moving your limbs and sensing sensations such as discomfort. Your eyes, hearing, tongue, nose, and nerves throughout your body gather information about your surroundings. The data is then transmitted to and from your brain via nerves. Neurons of various types send out messages in various ways.

Image 1: Sciencefacts

The Different Parts of the Nervous System

The Nervous System is divided into two main parts. The Central Nervous System, which comprises the brain and the spinal cord, and the Peripheral Nervous System, which is made up of all the body’s parts that are connected by nerves that emerge from the spinal cord. The Peripheral Nervous System is then divided into Sensory Division and the Motor Division. The Motor Division is then organized into the Somatic and Autonomic Nervous System. The Autonomic Nervous system is then finally composed of the Sympathetic and Parasympathetic Divisions.

Central Nervous System (CNS)

The brain and spinal cord contain the central nervous system (CNS). The central nervous system is the processing center of the body. The brain is in charge of the majority of the body’s operations, including awareness, movement, thinking, speaking, and the five senses of seeing, hearing, feeling, taste, and smelling.

The spinal cord is a brain addition. Through the network of peripheral nerves that link to it, it transmits and receives messages to and from the brain. (3)

Peripheral Nervous System (PNS)

Your peripheral nervous system is everything else, and it includes nerves that flow from your spinal cord and brain to feed your face and the rest of your body. The term “peripheral” is derived from the Greek phrase for “around or outside the center.”

The peripheral nervous system (PNS) is the part of your nervous system that is not directly connected to your brain or spinal cord. It is responsible for both transmitting information from various sections of your body back to your brain and carrying out commands from your brain to various parts of your body. Some of these signals are automatic, such as those to your heart and gut. Others, such as those that control locomotion, are under your command. (4)

Image 2: Cleveland Clinic

Sensory Division

The afferent division, also known as the sensory division, transfers impulses from peripheral organs to the CNS.

Motor Division

The efferent or motor division sends impulses from the CNS to the peripheral organs in order to produce an effect or action.

Somatic Nervous System (SNS)

The peripheral nervous system includes the SNS, which is connected with the voluntary control of body movements through the use of skeletal muscles. (6). The somatic nervous system’s primary roles are to transport sensory information from nerves to the central nervous system and to transport motor information from the central nervous system to muscles via motor neural pathways to govern their activity. The sensory-somatic nervous system is made up of cranial and spinal nerves, whereas the autonomic nervous system is made up of sensory and motor neurons that connect the CNS to the internal organs.

Autonomic Nervous System (ANS)

The autonomic nervous system is the part of your nervous system that controls automatic actions such as heartbeat and blood vessel widening or narrowing. When something goes wrong in this system, it can lead to major complications, such as high blood pressure. (5)

Sympathetic Nervous System (SNS)

Your autonomic nervous system is made up your sympathetic nervous system. It could be referred to as your “automatic” nervous system because it controls numerous functions that you do not have to think about. This includes, among other things, controlling your heart rate, blood pressure, digestion, urination, and sweating. Your sympathetic nervous system is most known for its role in responding to risky or stressful conditions. In certain conditions, your sympathetic nervous system acts to increase your heart rate, provide more blood to places of your body that require more oxygen, or perform other actions to assist you in escaping danger.

The majority of the impulses sent by your sympathetic nervous system originate in your spinal cord. The signals exit the spinal cord and trigger structures known as ganglia. Your sympathetic ganglia then sends the required signals to various sections of your body. Your heart, lungs, arteries, sweat glands, and digestive system could all be affected.

Your “fight-or-flight” response is controlled by your sympathetic nervous system. Danger or stress triggers your sympathetic nervous system, which can result in a variety of physiological reactions. In response to a threat or stress. These impacts assist you in situations where you must think or act swiftly. They enhance your vision, reflexes, endurance, and strength. Your sympathetic nervous system also activates when your body is under stress, such as when you exercise or are unwell.

Your sympathetic nervous system activity influences your immune system and the repair processes in your body. If you get harmed, these impacts can assist your body start healing faster. To communicate, your sympathetic nervous system employs molecules known as neurotransmitters. These substances are norepinephrine, epinephrine, and acetylcholine. (7)

Parasympathetic Nervous System (PNS)

The parasympathetic nervous system balances your sympathetic nervous system. While your sympathetic nervous system is in charge of your body’s “fight or flight” response, your parasympathetic nervous system is in charge of your body’s response when you are at rest. The primary function of the parasympathetic nervous system is to calm down or lessen your body’s activity. Because of the signals it sends, the rhyming phrases “rest and digest” or “feed and breed” are simple ways to recall what your parasympathetic nervous system performs.

Your parasympathetic nervous system is one of two parts of your autonomic nervous system. Your autonomic nervous system is a subsystem of your peripheral nervous system, which is all the nervous tissue in your body excluding your brain and spinal cord.

Your parasympathetic nervous system uses four of your 12 cranial nerves. These are nerves that connect directly to your brain. (8)

Image 3: Merck Manuals.

In the end, all these subsystems make up our Nervous System.

Akshaya Ganji, Youth Medical Journal 2022

References

Cleveland Clinic: “Nervous System”- https://my.clevelandclinic.org/health/articles/21202-nervous-system
NIH: “What are the parts of the nervous system?” – https://www.nichd.nih.gov/health/topics/neuro/conditioninfo/parts
Healthdirect: “Central nervous system (CNS)- https://www.healthdirect.gov.au/central-nervous-system
Cleveland Clinic: “Peripheral Nervous System (PNS)- https://my.clevelandclinic.org/health/body/23123-peripheral-nervous-system-pns
MedicinePlus: Autonomic Nervous System Disorders- https://medlineplus.gov/autonomicnervoussystemdisorders.html
National Library of Medicine: Neuroanatomy, Somatic Nervous System- https://www.ncbi.nlm.nih.gov/books/NBK556027/
Cleveland Clinic: Sympathetic Nervous System (SNS)- https://my.clevelandclinic.org/health/body/23262-sympathetic-nervous-system-sns-fight-or-flight
Cleveland Clinic: Parasympathetic Nervous System (PSNS)- https://my.clevelandclinic.org/health/body/23266-parasympathetic-nervous-system-psns