Nervous system basics for beginners | MPO training 6
This article explains the nervous system basics for beginners in a simple way.
If you want to become a Medical Promotion Officer (MPO), this will help you
understand the key points.
Diagram: Nervous system diagram
You will learn how the human nervous system works step by step. This short
guide is easy to read and beginner-friendly. You can explore this to build a
strong medical science base.
Table of content: Nervous system basics for beginners
Take a look at everything you can learn from this article.
Introduction
The nervous system basics for beginners include the brain, spinal cord, and
nerves. These parts work together to control body actions and responses.
You can easily understand how messages travel through nerves. This article
helps you learn it step by step. It is useful if you are preparing to be a
Medical Promotion Officer (MPO).
Nervous system basics for beginners
The nervous system is the chief controlling and coordinating system of the
body.
This system is responsible for providing conscious or unconscious control
of-
- Basic motor and sensory activity.
- Emotional and intellectual function.
Classification of Nervous System
Classification of Nervous System in details
Central Nervous System
Diagram: Central nervous system diagram1
Diagram: Central nervous system diagram2
Peripheral Nervous System
The peripheral nervous system is subdivided into:
- Sensory-somatic Nervous System
- Autonomic Nervous System
Diagram: Peripheral Nervous System
Sensory-Somatic Nervous System
The Sensory-Somatic Nervous System consists of-
- 12 pairs of cranial nerves and
- 31 pairs of spinal nerves
The Autonomic Nervous System
The autonomic nervous system consists of sensory neurons and motor
neurons that run between the central nervous system (especially the
hypothalamus and medulla oblongata) and various internal organs such
as the:
- Heart
- Lungs
- Viscera
- Glands (both exocrine and endocrine)
The autonomic nervous system has two subdivisions:
- Sympathetic Nervous System
- Parasympathetic Nervous System
Diagram: Sympathetic and Parasympathetic Nervous System
diagram
| Organ | Sympathetic Nervous System | Parasympathetic Nervous System |
|---|---|---|
| Brief Definition | Activates what is often termed the fight or flight response | Responsible for stimulation of "rest-and-digest" |
| Pupil | dilates pupils | Constricts pupils |
| Salivary Gland | decreases secretion | increases secretion |
| Heartbeat | increases heart rate | decreases heart rate |
| Bronchi | dilates bronchioles | constricts bronchioles |
| Stomach | Decrease peristaltic movement and secretions | Increase peristaltic movement and secretions |
| Pancreas | Decrease pancreatic secretions | Increase pancreatic secretions |
| GIT Movement /Peristalsis | Decrease GIT Movement /Peristalsis | Increase GIT Movement/Peristalsis |
| Digestive Juices | Decrease the secretions of Digestive Juices | Increase the secretions of Digestive Juices |
| Bile Secretion from Gallbladder | Decreased Bile Secretion from Gallbladder | Increase Bile Secretion from Gallbladder |
| Urinary Bladder | Inhibit urination | Stimulate urination |
What is Neuron?
Neurons are the basic structural and functional unit of the nervous
system. A neuron's job is basically to pass messages from one part
of the body to another.
Diagram: Neuron
Each Neuron consists of:
1) Nerve Cell Body
2) Nerve Processes:
- Axons
- Dendrites
Structure of A Neuron
Nerve Cell body: A cell body with nucleus and organelles
to provide for general metabolism and cellular maintenance.
Nerve Processes: Axons and dendrites are the processes of
the nerve cells that are also called nerve processes.
Diagram: Structure of a Neuron
Axons: A Long Fiber that carries impulses away from the
cell body, Each neuron has only one axon. The Axon Ends in a
series of small swellings called axon terminals.
Dendrites: Short branch spreading out from the cell body.
Dendrites receive stimulus (Action Potentials) and carry
impulses from the (Action Potentials) and environment or from
other neurons and carry them toward the cell body.
What is Synapse?
Synapse: The junction point from one neuron to the next, the
small gap or space between the axon of one neuron and the dendrites
or cell body on the next neuron is called the Synapse.
Diagram: Synapse diagram1
Diagram: Synapse diagram2
One importance of the presence of synapses is that they ensure
one-way transmission of impulses in a living person. A nerve impulse
cannot go backward across a Synapse.
Diagram: Synapstic Cleft
What is Neurotransmitter?
The Axon Terminals at a Synapse contain tiny vesicles, or sacs.
These tiny vesicles are filled with chemicals known as
Neurotransmitters.
- Example: (Acetylcholine)/Histamin.
A neurotransmitter is a chemical substance that is used by one
neuron to signal another.
The impulse is changed from an Electrical Impulse to a Chemical
Impulse (Electrochemical Impulses).
Classification of Neurotransmitter
Excitatory Neurotransmitter:
- Acetylcholine
- Norepinephrine
- Epinephrine
- Serotonin
- Prostaglandin
Inhibitory Neurotransmitter:
- GABA
- Glycine
- Enkephalin
- Endorphins
Nerve and Nerve Fiber
Nerve: A nerve is an enclosed, cable-like bundle of nerve
fibers called axons, in the peripheral nervous system. A nerve
transmits electrical impulses and is the basic unit of the
peripheral nervous system.
Diagram: Nerve and Nerve Fiber diagram
Nerve Fibers: A nerve fiber is a long process of nerve cells
(neurons) called the axon.
Nerve Fibers Classification
Nerve fibers can be classified by the following ways:
- Neurotransmitter at Synapse
- Mode of Function
- Myelination
1) Based on Neurotransmitter at synapse
Nerve fibers are of two types:
- Adrenergic: Nerve fibers that liberate noradrenalin at its synapse when transmitting a stimulus.
- Cholinergic: Nerve fibers that liberate acetylcholine at its synapse when transmitting a stimulus.
2) Depending on mode of function
Nerve fibers can be divided into two groups:
- Sensory / Afferent nerve fibers: These nerve fibers transmit impulses from the 2 2 periphery of the body to the spinal cord and then to the brain. Eg. Cold, touch, taste, sight etc.
- Motor / Efferent nerve fibers: These nerve fibers transmit impulses from the brain and spinal cord to different parts of the body.
3) Depending on the myelination (Covering of a sheath of fatty material)
Nerve fibers are of two types:
- Unmyelinated: Not covered by myelin sheath, common in brain and spinal cord.
- Myelinated: Covered by myelin sheath, common in periphery.
What is Hypothalamus?
The hypothalamus is composed of a group of nerve cells. It is
situated below and in front of the thalamus immediately above the
pituitary gland.
Hypothalamus is concerned with the control of:
- Control of hunger
- Thirst
- Body temperature
- Tone of heart and blood vessel
- Defensive reaction e.g. fear
Medulla oblongata
The medulla oblongata extends from the pons above (Midbrain) and is
continuous with the spinal cord below.
The groups of neurons present in the medulla oblongata constitute
vital centers associated with autonomic reflex activity, lie in its
deeper structure.
- Cardiac center
- Respiratory center
- Vasomotor (affecting the tone of blood vessels) center
- Reflex centers of vomiting, coughing, sneezing and swallowing
Centers
Respiratory Center: It controls the rate and depth of
respiration.
Reflex centers: When irritating substances are present in the
stomach or respiratory tract, nerve impulses pass to the medulla
oblongata, stimulating the reflex center, which initiates the reflex
action like vomiting, coughing and sneezing.
Cardiac Center: The sympathetic fibers increase the rate and
force of cardiac contraction. The parasympathetic fibers decrease
the rate and force of cardiac contraction.
Vasomotor Center: Vasomotor center sends impulses to the
blood vessel by sympathetic and parasympathetic nerve fibers. The
sympathetic stimulation causes vasoconstriction and the
parasympathetic stimulation causes vasodilation.
Spinal Cord
The continuation of nervous tissue of the brain down the spinal
canal to the level of the first or second lumbar vertebra. 31 pairs
of spinal nerves arise along the spinal cord. These are "mixed"
nerves because each contains both sensory and motor axons.
Diagram: Spinal Cord diagram
The spinal cord acts as a communication link between the brain and the
peripheral nervous system.
Spinal Nerves
Dorsal Roots: Contain Neurons that carry signals to the
central nervous system from various kinds of Sensory Neurons.
Diagram: Spinal Nerve diagram1
Ventral Roots: contain the Axons of Motor Neurons, which are
neurons that contact and carry information to the Muscles and Glands
(Effectors).
Diagram: Spinal Nerve diagram2
What is Meninges?
Both the spinal cord and brain are covered in three continuous
sheets of connective tissue, which are called the meninges.
From outside in, these are:
- Dura Mater
- Arachnoid Mater
- Pia Mater
Diagram: Meninges diagram
Cerebrospinal fluid (CSF)
- Cerebrospinal fluid (CSF), a secretion of the choroid plexus, is a clear colorless fluid.
- CSF flows uninterrupted throughout the central nervous system.
- Through the central cerebrospinal canal of the spinal cord.
- Through an interconnected system of four ventricles in the brain.
- CSF returns to the blood through veins draining the brain.
Diagram: Cerebrospinal fluid (CSF)
Functions of CSF
- It acts as a buffer to shock and protects the brain and spinal cord from damage due to body movement.
- It conveys nutritive material to the brain and spinal cord.
- It removes waste products from these structures.
Diagram: Functions of Cerebrospinal fluid diagram
FAQs
1. What is the basic function of the nervous system in the human body?
Answer: The nervous system controls body movements, senses, and thoughts. It
helps you react to your surroundings and keeps body functions running
properly.
2. Why should beginners learn about the nervous system?
Answer: Understanding the nervous system basics helps you know how your body
works. It is also a must-know topic for Medical Promotion Officer (MPO)
candidates.
3. What are the main parts of the human nervous system?
Answer: The main parts are the brain, spinal cord, and nerves. These parts
work together to send and receive messages in your body.
Conclusion
This article has explained the nervous system basics for beginners in a clear
and simple way. If you dream of working as a Medical Promotion Officer (MPO),
this basic knowledge will guide you. You now have a better idea of how the
human nervous system functions. It will help you in both your learning and job
preparation. Keep learning to grow your medical science skills.
Sarwar Hossain Himel
I am Sarwar Hossain Himel, I am a sports lover. Education: BBA & MBA in Accounting. Job: Medical Promotion Officer (MPO) & 5 years of teaching experience. Freelancing: Google blogger & Article Writer. Web Design is my passion.