What Is the Nervous System and What Does It Do?
The nervous system is composed of the central nervous system and the peripheric nervous system. The function of the nervous system is to send signals from one cell to others, or from one part of the body to others [1].
The term signal can refer to anything from electrical impulses to chemical messengers, to just plain old physical contact with another body part or cell.
1. What Is the Nervous System?
The nervous system is a network of cells that carries information throughout your body. The nervous system includes your brain, spinal cord, and nerves.
There are two parts to your nervous system: the central nervous system (CNS) and the peripheral nervous system (PNS). Your CNS includes your brain and spinal cord and your PNS includes all your nerves outside of these areas.
The function of the nervous system is to send signals from one cell to others, or from one part of the body to others. These signals are called neurotransmitters, chemicals that carry messages between cells in different parts of your body.
When you touch something hot, for example, sensory neurons in your hand send a message through a chemical called a neurotransmitter that tells another neuron in your brain what you touched.
2. What Is the Central nervous system
The central nervous system is the primary division of the nervous system consisting of the brain and the spinal cord.
The central nervous system is concerned with conscious control of bodily functions, such as voluntary movement, sensation, and thought.
The peripheral nervous system is concerned with unconscious control of bodily functions, such as blood pressure regulation, digestion, and glandular secretion.
Both systems are composed of neurons (nerve cells) that transmit impulses from one part to another or to effector organs such as muscles or glands.
2.1. The Brain
The brain is a part of the nervous system composed of two parts, the forebrain, and the hindbrain.
The forebrain is divided into the right cerebral hemisphere and the left cerebral hemisphere. The hindbrain is divided into the cerebellum, medulla oblongata, pons, and midbrain.
The cerebrum is a part of the forebrain which has two hemispheres connected by the corpus callosum. Each hemisphere consists of four lobes: frontal lobe, parietal lobe, occipital lobe, temporal lobe.
2.2. The Spinal Cord
The spinal Cord is a column of nerves that runs from your brainstem down to your lower back. There are 31 pairs of spinal nerves, which transmit signals from your brain to all parts of your body.
The spinal cord itself does not have any sensory or motor functions. However, it is an important part of our nervous system because it sends messages between our brain and other parts of our body through a network of nerves called ganglia.
These ganglia are located in different places throughout our bodies, such as in our arms, legs, hands, feet, etc., where they send information back up to our brains via nerve fibers known as axons.
3. What Is the peripheral nervous system
The peripheral nervous system is composed of all nerves outside of your brain and spinal cord. This includes your cranial nerves, which are responsible for controlling your sensory organs (eyes, ears, nose, tongue), as well as motor neurons that control muscles.
Peripheral nerves also include autonomic nerves that help regulate internal organs such as your heart or intestines. Your autonomic nervous system is also responsible for regulating blood pressure, body temperature, blood flow to internal organs, and other involuntary functions.
Because these processes are automatic, you don’t have to think about them, they just happen. Your autonomic nervous system works in conjunction with another part of your nervous system called the endocrine system.
The peripheral nervous system is the part of the nervous system that is outside of the brain and spinal cord.
The peripheral nervous system is a two-way communication network. This means that it has sensory neurons that detect stimuli from the environment and motor neurons that send signals to muscles to contract.
The peripheral nervous system can be divided into two parts: the autonomic nervous system and the somatic nervous system.
3.1. The somatic nervous system
The somatic nervous system is the portion of the peripheral nervous system that consists of sensory and motor nerves, and associated nerve tissue.
The somatic nervous system includes the cranial nerves, which are responsible for sensory information, and the spinal nerves, which are responsible for motor information.
The somatic nervous system also includes various nuclei (clusters of neurons) in the brainstem and spinal cord that control autonomic functions such as heart rate and blood pressure.
3.2. The autonomic nervous system
The autonomic nervous system (ANS) is a division of the peripheral nervous system that controls the body’s unconscious actions such as breathing, heartbeat, and digestion.
The ANS is made up of two parts: the sympathetic nervous system and the parasympathetic nervous system.
The two parts work together to maintain homeostasis in the body. When one is activated, the other becomes dormant.
For example, when you are feeling stressed or anxious, your sympathetic nervous system kicks in and your parasympathetic nervous system shuts down to help you manage these feelings.
3.2.1. The sympathetic nervous system
The sympathetic nervous system is often activated when we are in a stressful situation. It helps us to react quickly to events that might be dangerous or require immediate action. The fight-or-flight response activates certain organs that produce adrenaline and causes an increased heart rate and blood pressure, which provides more oxygen and energy for our muscles to use.
3.2.2. The Parasympathetic Nervous System
The Parasympathetic Nervous System is the part of the autonomic nervous system that stimulates “rest and digest” or “feed and breed” responses.
It is one of three divisions of the autonomic nervous system, along with the sympathetic nervous system and enteric nervous system.
3.2.3. The enteric nervous system
The enteric nervous system is a part of the autonomic nervous system that controls the function of the gastrointestinal tract. It is found in both vertebrates and invertebrates.
The enteric nervous system (ENS) consists of two nerve plexuses, one in the inner layer of muscle cells, and one around the outer surface of the intestinal wall.
The ENS can be divided into three main parts: The myenteric plexus, which regulates gut motility, the submucosal plexus, which receives sensory information from blood vessels and sends motor signals to glands in the intestine’s lining, and the intramural plexus is responsible for controlling intestinal secretions.
The myenteric plexus
The myenteric plexus is a subdivision of the autonomic nervous system. It is a network of nerve cells that are found in the muscular layer of the stomach and intestines. They are responsible for regulating intestinal movements and secretions.
The myenteric plexus is composed of two types of neurons: Auerbach’s plexus and Meissner’s plexus, which are both located in the submucosa.
The Auerbach’s plexus consists mainly of cholinergic neurons that secrete acetylcholine, while the Meissner’s plexus consists mainly of norepinephrine-secreting neurons.
In addition to these two types, there are also other neurons present
The submucosal plexus
The submucosal plexus is a network of nerve fibers that lies in the submucosa of the gastrointestinal tract. The nerves in this network are mostly unmyelinated and are derived from myenteric neurons.
This is a very complex network that transmits signals to other parts of the body, including the spinal cord and brain.
Conclusion
The nervous system is a vital part of the body that helps to control and coordinate all the body’s activities. It consists of the brain, spinal cord, and all the nerves that run throughout the body. The nervous system is responsible for sending and receiving messages between the brain and the rest of the body, and it plays a crucial role in keeping us healthy and functioning properly.
