Immunity: The gifted healing process


We live in a potentially hostile world filled with a bewildering array of infectious agents of diverse shape, size and composition so the whole human race has to create or acquire a defence mechanism to protect themselves from these particles. Earlier our ancestors are less knowingly know about the term defence mechanism in the daily routine. The term immunity is defined as the capability of a multicellular organism to resist harmful micro-organisms.

History and Origin of Concept Immunity :

The concept of Immunity was not known to mankind for a thousand years. Early, Man used to believe if any of the people are getting ill or not feeling well this happens because the person has done something wrong deeds in the supernatural powers punishes him.

 During the 19th century, Between the time of Hippocrates. People concluded that the diseases were caused by the ‘element’ which is present in the air or some dead particles.

Notable Personality with their significant discoveries under Immunity.

Prominent PersonalitiesDiscoveries
Al Razi The first description of immunity in “KItabi fi al Jabari was-al-hash.
Ilya MechnikovThe first scientist developed a full theory of immunity.
Louis Pasteur The germ theory of disease, Immunology.
Universal Antidote It is a sub-lethal dose of venom to build tolerance also known as MIthridateMithridates VI of Potitus (120-63 B.C.)
Vaccination to trigger an immune responseEdward Jenner.


Immunology is the study of the immune system or once immunity and it is a very important branch in medical and biological sciences. Emil von Behring is the father of Immunology. Immunology has applications in numerous medical disciplines, particularly in organ transplantation, oncology, parasitology, psychiatry, and dermatology.

Immunology also deals with physiological functions of the immune system as well as malfunction of the immune system in immunological disorders like allergies, hypersensitivities, immune deficiency, transplant rejection and autoimmune disorders.

Immune system and Immunology

Organs associated with the immune system or Immunity system:

Our immune system has made up of both individual cells and protein and as well as the entire organ and organ system.

Lymphoid Organs

The lymphatic system had composed of following lymphoid organ

Immune system.

 Primary lymphoid organs: Including the bone marrow and the thymus. They create special immune system cells called lymphocytes.

Secondary lymphoid organs: These organs include the lymph nodes, the spleen, the tonsils and certain tissues in various mucous membrane layers of the body. Medical, in adulthood these medical, in adulthood organs, the cells of the immune system do their actual job of fighting off germs and foreign substance.

Bone marrow

It has a sponge-like tissue found inside the bones. Bone marrow is the primary site of new blood cells production or haematopoiesis. That’s where most immune system cells had produced and then also multiply. At the time of birth, many bones contain red bone marrow which actively creates immune system cells.  Although, only a few of our bones still contain red bone marrow in adulthood, including the ribs, breastbone, and pelvis.


The thymus is located behind the breastbone above the heart. The gland-like organ fully maturity only in children and has then slowly transformed into fatty tissues. They produce special types of immune cells which has known as thymus cells. Lymphocytes(T-cells) mature in the thymus.

Lymph nodes

Lymph nodes had small bean-shaped tissues found along the lymphatic vessels. The lymph nodes act as filters. Various immune system cells trap germs in the lymph nodes and activate the creation of special antibodies in the blood. Swollen or painful lymph nodes are a sign that the immune system is active, for example, to fight infection.


The spleen is located in the left upper abdomen, beneath the diaphragm, and is responsible for different kinds of jobs:

  1. It stores various immune system cells. When needed, they move through the blood to other organs. Scavenger cells (phagocytes) in the spleen act as a filter for germs that get into the bloodstream.
  2. It breaks down red blood cells (erythrocytes).
  3. It stores and breaks down platelets (thrombocytes), which are responsible for the clotting of blood, among other things.

There is always a lot of blood flowing through the spleen tissue. At the same time, this tissue is very soft. In the event of severe injury, for example in an accident, the spleen may rupture easily. Surgery is then usually necessary because otherwise there is a danger of bleeding to death. If the spleen needs to be removed completely, other immune system organs can carry out their roles.


The tonsils are also part of the immune system. Because of their location at the throat and palate, they can stop germs from entering the body through the mouth or the nose. The tonsils also contain a lot of white blood cells, which are responsible for killing germs. There are different types of tonsils: palatine tonsils, adenoids and the lingual tonsil. All of these tonsillar structures together are sometimes called Waldeyer’s ring since they form a ring around the opening to the throat from the mouth and nose.

There has also lymphatic tissue on the side of the throat, which can perform the functions of the palatine tonsils if they have removed.

Types of Immune System or Immunity system:

Innate Immunity:

Innate responses are non specific responses for defences.

Natural Resistance:

Naturally, resistant host either fail to provide some of the essential growth factor required by micro-organisms or have a defence mechanism to resist infection.

Species Resistance:

 Resistance to infection varies with species of animals, plants and humans. Therefore, the pathogen that affects plants do not affect animals and also human and vice versa. Basic physiological characteristics of a species such as normal body temperature, normal flora, biological structure affect species resistance.

For example:- Skin diseases associated with humans are resistant to animals because they have thicker hair follicle different skin flora and the presence of hides.

Racial Resistance:

Various races or breeds of animals are prone to be resistant to certain diseases. For example:- Europeans are resistant to Tuberculosis whereas American-Indians staying in Europe are susceptible to tuberculosis.

Individual Resistance:


Personal hygiene keeps away pathogenic microbes and stops their spread. Therefore, the interaction of pathogen and host is reduced and chances of infection are reduced. It increases once immunity.


 Age is an important factor in susceptibility to infectious disease are more common in very young and old individuals. In addition, age anatomical changes in various body tissue promote the growth of pathogenic micro-organisms.

Diet and Nutrition:

    Diet plays an important role in host resistance. Overeating leads to excessive bloating and gas accumulation because of the massive growth of bacterium species normally present in low numbers. Lack of dietary substance may present diseases depriving a pathogen of critical nutrients.


    The importance of genetic factor for pathogen and host influences host susceptibility to infection often. One host species is resistant to an infectious disease as compare to others. Genetically determined factors depend on

(a) the Temperature of the host. 

(b) Metabolic physiology and anatomical differences.

(c) Food mechanism or food habitat.

above factors can help in sustaining immunity

Stress :

Stress predisposes normal healthy individuals to diseases. Fatigue, exertion, poor diet, dehydration, drastic climatic change are reasons for physiological stress. High activity accounts for physical stress. Immunity can be suppressed if stress level increases.


Hormones influenced the immune system and play a role in stress-mediated disease for example hormone cortisol is produced at high concentration in times of stress which has anti-inflammatory action as a result of the defence mechanism of the individual is suppressed.

Sex hormone such as oestrogen, progesterone and testosterone also modulates an individual immune system. Women are more susceptible to auto-immune disorders than men.

Acquired Immunity:

Acquired Immunity is immunity that develops over your lifetime. When pathogens (germs) are introduced into your body from a vaccine or a disease, your body learns to target those germs in the future by making new antibodies. Antibodies from another person can also help your body fight infection but the type of the immune system is temporary.

Acquired immunity is different from innate immunity which you’re born with. Your immune system doesn’t fight specific germs. Instead, it protects against all germs, like bacteria and viruses by trying to keep them away from entering your body.

Types of Acquired immunity:

Active Immunity: Active immunity is the most common type. It develops in response to an infection or vaccination. These methods expose your immune system to a type of germ or pathogen.

Immune cells called T and B cells recognize there’s an “invader” pathogen and activate the immune system to fight it.

The next time then T and B immune cells are encounter that specific germ, they will recognize it and immediately activate the rest of your immune system to prevent you from getting sick.

Passive Immunity: Passive immunity develops after from someone or somewhere else. The type of immunity is short-lived because it doesn’t cause your immune system to recognize the pathogen in future.

There are two types main types of passive immunity.

Maternal antibodies: Maternal antibodies are antibodies that transfer from a mother to a child. This is usually happening across the placenta or through breastmilk, especially in the first few days after birth.

Immunoglobulin treatments: Immunoglobins are antibodies that are usually used to treat people at risk for infections, like after a snakebite or a baby born to a mother with hepatitis B. These antibodies are made in a lab or come from other people or animals.

Difference between Natural and artificial immunity

Both natural and artificial sources of immunity can be active or passive.

Natural immunity: Natural Immunity isn’t specifically given to you to boost your immunity. Instead, they’re something you acquire by natural means, like an infection or from your mother during birth.

Artificial immunity: Artificial immunity is given to you for a specific purpose. They include vaccinations or immunoglobulin treatments.


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