Biology - Immune System

The immune system is a network of cells and proteins that fight against infections and keeps records of any infection it has ever defeated. This is the reason why the immune system is able to recognize and destroy previous infections that enter the body.

Immune System

The human immune system is made up of special organs, cells, and chemicals that defend the body from infections(microbes). The major parts are the white blood cells, antibodies, lymphatic system, etc come together to actively fight infections.

The immune system keeps records of microbial infections that it has ever defeated, the B- and T-lymphocytes help to recognize and destroy microbes. An example of some of these infections is the flu and common cold, which the immune system has to fight so many times due to the different viral strains.

Parts of the immune system

White blood cells(WBC)

WBC is a key player and moves through blood and tissue looking for foreign invaders (bacteria, viruses, etc) to launch immune attacks.


Antibodies help the body to recognize antigens on microbes that are toxins and fight them.

Complement system

Complement systems are protein-like features that complement the actions of antibodies

Lymphatic system

The lymphatic system is a network of tubes throughout the body that manage fluid levels, bacterial reactions, absorption of fats, deal with cancer cells, etc.


The spleen is a disease-fighting component and a blood-filtering organ of the immune system. The spleen helps in separating microbes and destroys such damaged red blood cells.

Bone marrow

Bone marrow is a major part of the immune system, spongy tissue inside the bone. Bone marrow produces red blood cells for oxygen transmission, white blood cells for defense, and platelets for blood clotting.


Thymus monitors and filters blood content.

The body's other defenses against microbes

Defenses against microbes have not just been the job of the income system, other body parts have been of great help in fighting against microbes.

  • Skin (waterproof and contain bacterial killing properties)
  • Lungs (Mucous and small tiny hairs to trap foreign particles)
  • Digestive tract (Mucous antibodies lining and acidic nature to kill most microbes)
  • Other defenses (Skin oil, saliva, and tear containing antibacterial enzymes)
  • The urinary tract and the bowel also help

I will end here. We have seen how the immune system is a vital body part. It keeps the record of the microbes it has ever defeated and identifies them, and quickly fights against them. This is why our immune system easily identifies situations like flu and the common cold to fight when we are attacked. Next, I will take us through some common disorders of the immune system.


Future reading