Children, both infants and toddlers tend to fall ill more often and are more prone to infections as they do not have a fully developed immune system, compared to adults. Likewise, as people grow old, their immune system weakens and makes things worse.
Every person has a different immune system and it varies with age, lifestyle and there are many factors which affect the immune system of a human being.
The Immune System consists of different types of cells and molecules, which protect our body against pathogens. Pathogens are defined as everything from parasites to fungi, bacteria, viruses and haptens. Haptens are molecules that may cause an immune response when they come in contact with a protein. All these cells and molecules are divided equally in all the tissues of the body as well as lymphoid organs, which eliminate or prevent microbial infections to decrease the growth of tumours and start the repairing process of damaged tissues.
Types of Immune System
Immune System fights against microbes and is divided into different types of reactions. The three types of immunity are:
Innate Immunity
We all are born with innate (or natural) immunity, a type of natural protection.
The immunity that is attached to us by birth is defined as the Innate Immunity. It refers to the defence system of the body which helps a person to fight diseases off.
For example, the skin, the barrier of the human body functions by protecting the entry of germs and other disease-causing pathogens.
Adaptive Immunity
When an individual acquires immunity after birth that is termed as adaptive or acquired immunity. Adaptive immunity develops throughout our lives. We acquire an immunity when we are exposed to infectious diseases and allergies or when we are immunized against them with vaccines, that is termed as adaptive immunity.
Passive Immunity
This is a kind of immunity developed by antibodies that are produced outside the body. This immunity lasts for a short time. For example, the antibodies that are present in a mother’s breast milk gives a baby with temporary immunity against the diseases.
Active Immunity
Active immunity is a type of adaptive immunity, which is developed due to the production of antibodies in one’s own body. This type of immunity occurs when we are in contact with the pathogen or its antigen. When the active immunity happens for the first time, it is called a primary response. Once a body experiences a pathogen for the first time, it keeps a few of the antibodies that attacked the pathogen just in case it attacks for the second time..
What are the Parts of the Immune System?
The main parts where the immune system can be found are -
Spleen.
Thymus.
Antibodies.
Bone marrow.
White blood cells.
Lymphatic system.
Complement system.
Disorders of the Immune System
Some of the common disorders caused by a poor immune system include:
Allergic diseases – These are the diseases which have symptoms which include hay fever, sinus disease, asthma, hives, dermatitis and eczema.
Autoimmune diseases – These include multiple sclerosis, autoimmune thyroid disease, type 1 diabetes, systemic lupus erythematosus, rheumatoid arthritis and systemic vasculitis.
There are immunodeficiencies, which are inherited from a parent to the child. These conditions include primary immunodeficiency diseases such as x-linked severe combined immunodeficiency (SCID), complement deficiencies, common variable immunodeficiency (CVID), etc
FAQs on Immunity System
1. What is the main job of the immune system?
The main job of the immune system is to protect our body from harmful invaders like bacteria, viruses, fungi, and other pathogens. It acts as a defence force that identifies, attacks, and remembers these germs to keep us healthy and prevent future infections.
2. What are the two main types of immunity in our body?
Our body has two main types of immunity:
- Innate Immunity: This is the general, all-purpose defence system we are born with. It provides the first line of defence against any invader, using physical barriers like skin and non-specific cells.
- Adaptive (or Acquired) Immunity: This is a highly specific defence that our body develops over time. It learns to recognise particular pathogens and creates a long-lasting memory, allowing for a faster, stronger response to future infections.
3. What is the difference between active and passive immunity?
Active and passive immunity are both types of adaptive immunity, but they are acquired differently. Active immunity develops when your own body produces antibodies after an infection or a vaccination. This type is long-lasting. In contrast, passive immunity is when you receive ready-made antibodies from an external source, such as a mother passing them to her baby through milk. This protection is immediate but only temporary.
4. What are the main organs of the immune system?
The immune system's main organs, known as lymphoid organs, include the bone marrow, thymus, spleen, and lymph nodes. The bone marrow and thymus are primary organs where immune cells are produced and mature. The spleen and lymph nodes are secondary organs where immune cells are activated to fight infections.
5. How does a vaccine actually work with our immune system?
A vaccine works by safely introducing a harmless part of a pathogen, like a weakened virus or a specific protein, into the body. This exposure doesn't cause illness but it's enough to trigger the adaptive immune system. The system then produces specialised antibodies and memory cells, preparing it to quickly recognise and destroy the real pathogen if it ever invades in the future.
6. What are antibodies and what do they do?
Antibodies are special Y-shaped proteins made by our immune cells (specifically B-lymphocytes). Their role is to find and attach to specific markers on pathogens called antigens. By binding to these antigens, antibodies can either neutralise the threat directly or flag the pathogen for destruction by other immune cells.
7. If the immune system is for defence, why does it sometimes attack the body's own cells?
This happens in conditions called autoimmune disorders, such as rheumatoid arthritis or Type 1 diabetes. It occurs when the immune system loses its ability to distinguish between the body's own healthy cells ('self') and foreign invaders ('non-self'). As a result, it mistakenly launches an attack against its own tissues, causing inflammation and damage.
8. How does the body 'remember' a disease it has fought before?
The immune system's memory is a crucial part of adaptive immunity. After fighting off a pathogen for the first time, some of the specialised B-cells and T-cells that were involved become long-living memory cells. These cells circulate in the body for years. If the same pathogen enters again, these memory cells recognise it immediately and launch a much faster and more powerful attack, often stopping the infection before any symptoms appear.
