The immune system is the body’s defense against infectious organisms and other invaders. … One of the important cells involved are white blood cells, also called leukocytes, which come in two basic types that combine to seek out and destroy disease-causing organisms or substances.
How Does the Immune System Work?
When the body senses foreign substances (called antigens), the immune system works to recognize the antigens and get rid of them.
B lymphocytes are triggered to make antibodies(also called immunoglobulins). These proteins lock onto specific antigens. After they’re made, antibodies usually stay in our bodies in case we have to fight the same germ again. That’s why someone who gets sick with a disease, like chickenpox, usually won’t get sick from it again.
This is also how immunizations (vaccines) prevent some diseases. An immunization introduces the body to an antigen in a way that doesn’t make someone sick. But it does let the body make antibodies that will protect the person from future attack by the germ.
Although antibodies can recognize an antigen and lock onto it, they can’t destroy it without help. That’s the job of the T cells. They destroy antigens tagged by antibodies or cells that are infected or somehow changed. (Some T cells are actually called “killer cells.”) T cells also help signal other cells (like phagocytes) to do their jobs.
Humans have three types of immunity — innate, adaptive, and passive:
- Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection. For example, the skin acts as a barrier to block germs from entering the body. And the immune system recognizes when certain invaders are foreign and could be dangerous.
- Adaptive immunity: Adaptive (or active) immunity develops throughout our lives. We develop adaptive immunity when we’re exposed to diseases or when we’re immunized against them with vaccines.
- Passive immunity: Passive immunity is “borrowed” from another source and it lasts for a short time. For example, antibodies in a mother’s breast milk give a baby temporary immunity to diseases the mother has been exposed to.
In our current situation of covid-19 immune system plays vital role we should eat those things which can make our immune system stronger and helps to fight with bacteria.
Everyone’s immune system is different but, as a general rule, it becomes stronger during adulthood as, by this time, we have been exposed to more pathogens and developed more immunity.
That is why teens and adults tend to get sick less often than children.
Once an antibody has been produced, a copy remains in the body so that if the same antigen appears again, it can be dealt with more quickly.
That is why with some diseases, such as chickenpox, you only get it once as the body has a chickenpox antibody stored, ready and waiting to destroy it next time it arrives. This is called immunity.



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