Question

Define the term immunity and immune system.

Answer 1

Hint: Immunity is the capacity of multicellular organisms to resist microorganisms that are toxic. Immunity requires both unique and non-specific components.

Complete Answer:
- Immunity can be characterised as a complex biological system with the capacity to recognise and tolerate what belongs to oneself and to recognise and reject what is foreign (non-self).
- The body's protection against infection is the immune system. Germs are attacked by the immune system and help to keep us safe. To protect the body, a lot of cells and organs function together.
- White blood cells , also known as leukocytes, play an important function in the immune system. Some types of white blood cells, called phagocytes, chew invasive species. Others, called lymphocytes, help the body remember and kill the invaders.
- One form of phagocyte is a neutrophil that fights bacteria. If anyone may have a bacterial infection, doctors may order a blood test to see if it produced a lot of neutrophils in the body.
- Other forms of phagocytes do their own work to ensure that the body responds to invaders. As the body detects foreign compounds (called antigens), the immune system acts to identify and eliminate antigens.
- B lymphocytes are activated to produce antibodies (also called immunoglobulins). These proteins are locked onto particular antigens. Typically, after they are made, antibodies will remain in our bodies if we have to battle the same germ again. That's why someone who gets sick with a disease, like chickenpox, usually doesn't get sick again.

There are three types of immunity namely
(I) Innate- This is a type of general protection
(II) Adaptive- This develops throughout the life
(III) Passive- It is borrowed from another source which lasts only for a short time.

Note: Similarly, immunisation or vaccination also prevents some illness. Immunization, in a manner that does not make someone ill, exposes the body to an antigen. But let the body generate antibodies that will protect the individual from possible germ attacks.