What happens when an antigen enters the body and how does the immune system fight it off?

The first line of defense the body has is non-specific defense. The skin, mucus membranes, and nose hair act as a barrier to the microbes.

If the microbe passes through and enters the body, the second line of defense is activated. Phagocytes are a type of white blood cells that absorb bacteria and particles. They release digestive enzymes that break down microbes before harm takes place.

The invading microbe is then called an antigen after passing through both lines of defense. When an antigen enters the body, the immune systems creates antibodies against it. This is called Specific Defense.

The B-cells in the immune system are triggered to produce antibodies. These special antibodies lock onto antigens to protect the body. The antibodies need help destroying the antigen. T-cells destroy antigens.

Inflammation occurs when the body is damaged by bacteria and toxins.

Sources:

Aryal, Sagar. “B Cells (B-Lymphocytes).” Online Microbiology Notes, 3 Jan. 2020, microbenotes.com/b-cells-b-lymphocytes/.

“Immune System (for Parents) - Nemours KidsHealth.” Edited by Larissa Hirsch, KidsHealth, The Nemours Foundation, Oct. 2019, kidshealth.org/en/parents/immune.html.

Society, Microbiology. “Immune System: Microbes and the Human Body.” Microbes and the Human Body | Microbiology Society, microbiologysociety.org/why-microbiology-matters/what-is-microbiology/microbes-and-the-human-body/immune-system.html.