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Immune System

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  • Last Updated : 27 Sep, 2022
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The immune system is made up of a large network of organs, white blood cells, proteins (antibodies), and chemicals. Together, these components’ defense system guard the affected person against external invaders (bacteria, viruses, parasites, and fungi) that can lead to illness, disease, and infection. A healthy immune system keeps infections out of the body and, if they do, destroys them or lessens their damage. Get enough sleep, get active, eat well, maintain a healthy weight, manage stress, and practice other healthy habits to maintain a strong immune system.

How does the Immune Response Operate?

When the immune system is in optimal condition: The immune system can distinguish between one’s own cells and chemicals that are foreign to the body when it is functioning properly. It energizes, mobilizes, engages in combat with, and eradicates potentially harmful foreign invader microbes. The immune system recognizes infections once it’s been exposed to others. The body creates antibodies to protect from specific diseases. When anyone receives a vaccine, for instance, this idea is demonstrated. The immune system develops antibodies to the foreign cells in the vaccination, which it will swiftly recognize and destroy. If the person gets sick, the doctor may occasionally recommend antibiotics to boost the immune system. But only some germs are killed by drugs. They do not eradicate viruses.

When the immune system is underperforming: When the immune system fails to successfully fight off an intruder, a problem, such as an infection, arises. Additionally, the immune system may occasionally launch an assault even in the absence of an invader or continue to do so even after the enemy has been eliminated. Allergies and autoimmune illnesses are issues brought on by these behaviors.

What Components make up the Immune System?

The immune system is composed of an intricate network of tissues and organs. They all cooperate to keep sterile and aid in Body’s recovery from illnesses. The immune system is composed of

White blood cells White blood cells hunt down, attack, and eliminate germs to keep a person healthy by acting as an army against dangerous bacteria and viruses. The immune system’s core component is white blood cells. There are various different types of white blood cells in our immune system. Each cell type either sits in a certain tissue and waits to be activated or circulates in the bloodstream and throughout the body. Every sort of cell in the body’s defensive system has a specific function. Each has a unique technique for identifying a problem, interacting with other defense team cells, and carrying out their assigned task.
Lymph Nodes These tiny glands filter and eliminate pathogens to prevent them from infecting other areas of the body. The lymphatic system in the body also includes them. Immune cells found in lymph nodes examine outside invaders that enter the body. The targeted lymphocytes are then activated, reproduced, and sent to combat that specific invader. Numerous lymph nodes can be found throughout the body, including the neck, armpits, and groin.
Spleen White blood cells that protect a body from foreign invaders are kept in the spleen. It also filters Human Body blood, eliminating red blood cells that are aging, hemoglobin defense-enhancing, or damaged.
Tonsils and Adenoids Because they are situated in the nasal passage and the throat, tonsils, and adenoids can catch foreign invaders like bacteria or viruses as soon as they enter the body. Immune cells in the body that make antibodies can defend against foreign invaders that can infect our lungs and throat.
Thymus This little organ in the upper chest, below the breastbone, aids in the maturation of a particular type of white blood cell. This cell’s unique duty is to become familiar with an invader so that it can be rapidly attacked the next time it is met.
Bone marrow Stem cells in the soft center of the body’s bones give rise to a range of white blood cells, immune cells, and red blood cells, including hemoglobin and plasma cells. Every day, the bone marrow creates billions of new blood cells and releases them into the blood.
First-line defenses include the skin macrophages and mucous membranes The first line of defense against preventing and eliminating infections from entering is the organism’s skin. In addition to secreting other defense-enhancing immune cells, skin generates oils. The respiratory, digestive, urinary, and reproductive pathways are lined with mucous membranes. The mucus is secreted by these membranes, lubricating and moistening surfaces. Cilia, which resemble hair-like structures, transport germs out of the airways by adhering to mucus in the respiratory system. The nose’s tiny hairs act as a germ magnet. Enzymes may both guard against and eradicate germs, and they can be found in sweat, tears, saliva, mucous membranes, and vaginal secretions.
Bowel and stomach As soon as bacteria enters the body, stomach acid quickly kills them. Additionally, intestines contain helpful (good) bacteria that eliminate dangerous bacteria.


By mimicking the body’s natural immunological response, vaccinations work. The body is given an injection of a vaccine process known as Immunization, which is a small quantity of a specially prepared virus, bacteria, or toxin. The body responds by producing antibodies. A person who has had a vaccination won’t get sick if they are exposed to the actual virus, bacteria, or toxin because their body will recognize it and know how to effectively combat it.

There are vaccines available for various illnesses, including tetanus and measles. The vaccinations could require to depend on organism health, age, way of living, and line of work. These elements are collectively known as HALO, which is defined as:

  • Health: Certain health issues or variables may increase organism susceptibility to infections that can be prevented by vaccination. For instance, they may benefit from more or more frequent immunizations if a person has HIV, Down syndrome, asthma, diabetes, heart, lung, spleen, or other health issues.
  • Age: Need protection from different vaccine-preventable diseases at different ages. The National Immunization Program of Australia outlines advised vaccinations for infants, kids, seniors, and other groups at risk, such as Aboriginal and Torres Strait Islanders. The majority of advised vaccinations are free for these people to receive.
  • Lifestyle: The immunization requirements may be impacted by one’s lifestyle decisions. If the person plans to travel abroad, start a family, engage in sexual activity, smoke, or play a contact sport that could expose him to another person’s blood, he may benefit from getting more or more frequent immunizations.

Types of White Cells

Macrophages The largest type of white blood cell is called a monocyte. Monocytes called macrophages are found in almost every type of tissue. They grab cells and pathogens and devour them through a process known as phagocytosis. After being consumed, the pathogen is eliminated by hydrolytic enzymes released by the macrophage lysosomes.
Dendritic Cells Similar to the dendrites of neurons, dendritic cells have projections that extend from the body of the cell. They are frequently discovered in tissues in organs that interact with the outside world, such as the skin, nose, lungs, and digestive tract.
B Cells B cells belong to the lymphocyte subclass of white blood cells. To combat diseases, B cells create specialized proteins called antibodies. By attaching to infections and directing other immune system cells to kill them, antibodies aid in the identification of pathogens.
T cell T cells are lymphocytes as well. Bone marrow produces T lymphocytes, which then go to the thymus to develop. T cells actively kill contaminated cells while directing other immune cells to join the immunological response.
Neutralizing T-Cells Natural killer (NK) cells are lymphocytes that scavenge sick or infected cells from the bloodstream. Granules with substances inside are present in natural killer cells. The NK cells surround and kill the diseased cell by releasing the chemical-containing granules when they come across a tumor cell or a cell that is virus-infected.
Neutrophils White blood cells known as neutrophils fall within the granulocyte category. They are phagocytic and have granules that contain chemicals that kill microorganisms. Neutrophils have a single nucleus that seems like it has several lobes. The majority of granulocytes in blood circulation are these cells.
Eosinophils White blood cells called eosinophils are phagocytic and become more active during allergic reactions and parasite infections. Granulocytes called eosinophils to have big granules inside of them and produce chemicals that kill germs. The connective tissues of the stomach and intestines frequently include eosinophils.
Basophils Granulocytes called basophils have histamine and heparin in their granules. Heparin thins the blood and prevents the development of blood clots. Histamine widens blood arteries and boosts blood flow, aiding the delivery of white blood cells to areas that are contaminated.

Kinds of Immunity 

Three different categories of immunity exist:

  • Innate immunity: The body uses it as its first line of defense. It consists of defenses like the skin and mucous membranes. They prevent dangerous toxins from getting into the body. Additionally, it consists of various chemicals and cells that might harm external objects.
  • Active immunity: When persons/children are infected with or immunized against a foreign substance, active immunity, also known as adaptive immunity, develops. Active immunity typically lasts for a long time. It can last entire life for many illnesses.
  • Passive immunity: Acquire antibodies to a disease rather than producing them. For instance, newborn infants inherit their mother’s antibodies. Additionally, antibodies found in blood products can give people passive immunity. You immediately receive protection against this type of immunity. However, it only lasts for a few weeks or months.

Immune System Conditions

Here are a few typical instances:

  • Severely compromised immune system (SCID): This is an example of an immune disease that develops at birth. The danger of bacterial, viral, and fungal infections in children is constant. This sickness is also known as “bubble boy illness” at times. In the 1970s, a youngster was forced to live in a plastic bubble where everything was sterile. Children with SCID lack crucial white blood cells.
  • Developed immune weaknesses that are temporary: For instance, several medications can impair the immune system. This may happen to people taking chemotherapy or other cancer-treating drugs. It can also happen to transplant recipients who take medicine to prevent organ rejection. Immunity can also be momentarily weakened by illnesses like measles, mono (mononucleosis), and the flu virus. The immune system may also be harmed by poor dietary habits, drinking, and smoking.
  • AIDS: An acquired viral infection called HIV, which results in AIDS, kills crucial white blood cells, and impairs the immune system. People with HIV/AIDS develop severe infections that the majority of people can fend off. Opportunistic infections are what these infections are known as because they profit from weakened immune systems.

Adaptive Immunity

Multiple immune system components make up the human body. Numerous cellular activities are part of these subsystems, which aid in defending humans from disease.”Adaptive immunity uses specialized immune cells and antibodies in the defense against foreign intruders.” A new immune response can be created in response to these substances in the future to prevent illnesses.


  • Eliminating bacteria and the toxin-producing enzymes they create.
  • Identification of non-self antigens when self-antigens are present.
  • Remembering illnesses and cells that cause disease and getting rid of them during a subsequent attack.
  • Defend against infectious illness pathogens through B- and T-lymphocyte-mediated mechanisms.


Immunodeficiency conditions make it difficult for the body to fight against illnesses and infections. Organisms are more likely to contact with viruses and bacterial illnesses if organisms have this kind of condition.

Immunodeficiency disorder can be either inherited or acquired. Organisms are born with a congenital, or primary, disease. A secondary or acquired disorder is one that develops later in life. Congenital disorders are less frequent than acquired disorders.

Signs of an immunodeficiency disorder

There are hundreds of forms of immunodeficiency disorders. Each illness has distinct symptoms that may be recurrent or persistent. Those who suffer from immunodeficiency disorders frequently get infections of certain illnesses, such as:

  • Pink eye
  • Sinus infections
  • Thrush
  • Colds
  • Chronic gum disease 
  • Pneumonia
  • Yeast infections

Immunodeficiency condition sufferers may experience chronic stomach pain as well as weight loss over time.

Excessive Immunological Response

The immune system may respond to chemicals in the environment that are typically safe if you were born with specific genes. Allergens are these compounds. The most typical manifestation of a hyperactive immune system is an allergic reaction. Some ailments brought on by an overactive immune system include:

  • Asthma: Human Body lung’s reaction may result in coughing, wheezing, and difficulty breathing. Common allergens like dust or pollen or an irritant like tobacco smoke might set off an asthma attack.
  • Eczema: Atopic dermatitis is an itchy rash brought on by an allergen.
  • Allergic rhinitis: Sneezing, running nose, sniffling, and nasal passage swelling brought on by indoor allergens like dust and pets or outdoor allergens like pollens or molds.

Autoimmune Diseases

When autoimmune illnesses occur, the body attacks normal, healthy tissues. There is no known cause. Most likely, a person’s genes are activated by both something in their environment and their genes. There are three prevalent autoimmune diseases:

  • Type 1 diabetes: The pancreatic cells that produce insulin are attacked by the immune system. Sugar is taken out of the blood by insulin and used as fuel.
  • Arthritis Rheumatica: The joints become swollen and malformed as a result of this type of arthritis. Some sufferers of rheumatoid arthritis have rheumatoid factor auto-antibodies in their blood.
  • Lupus: This illness targets organs such as the skin, kidneys, and lungs. Blood samples from lupus sufferers are shown to contain a wide variety of auto-antibodies.

Tips for a Strong Immune System

The immune system needs nutrition, rest, and a healthy environment to remain robust, just like the rest of the body. The immune system can be strengthened and illnesses prevented by making some lifestyle adjustments.

  1. Give up smoking.
  2. Maintain a healthy body mass or lose weight.
  3. Consume a balanced diet rich in fruits and vegetables that is healthy.
  4. Alcohol should be avoided or used sparingly.
  5. Get adequate rest.
  6. Regular exercise
  7. Regularly wash Human Body hands.
  8. Lessen body stress and concentrate on the body’s overall wellness.
  9. Make sure Human Body vaccinations are current.

FAQs on Immune System

Question 1: Which vitamins strengthen the immune system?


The benefits of vitamins B6, C, and E on the immune system are well documented. 

Question 2: What indicates a compromised immune system?


A compromised immune system is characterized by frequent colds, infections, digestive problems, slow wound healing, skin infections, tiredness, organ problems, slow growth, blood disorders, and autoimmune illnesses. The immune system contributes to the body’s defense against dangerous diseases and other environmental threats.

Question 3: Which blood test reveals the immune system?


Three distinct types of immunoglobulins are typically measured by an immunoglobulin test. They go by the names of IgG, IgM, and IgA. IgG, IgM, or IgA levels that are abnormally low or high could indicate a dangerous medical condition.

Question 4: When does the Human Body’s immune system begin to deteriorate as you get older?


The immune system weakens with age, which is a major factor in why those over the age of 70 are most susceptible to the disease.

Question 5: When is the best time of day immune system to work properly?


The immune system’s defense against bacterial invasion is most active at night and least active during the day.

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