The complement system is barrier of the immune system. a complement system is a group of in the blood that detect pathogens that have entered the body. the complement system can cause the swelling of a part of the body accompanied by redness, swelling, and pain as a response to infection.

1. The right answer is biological.

The nonspecific response, which constitutes innate immunity, works by not taking into account the type of disease it is fighting. It is the first line of defense against an infection. Several types of mechanisms intervene during this response:

* physical barriers (skin, mucous membranes, tears...)

* inflammation;

* cells of innate immunity:

* complement: it is a group of proteins that plays a role in immunity.

2. The right answer is proteins.

The complement system is a group of 25 known serum proteins, part of the innate immunity. Twelve (12) of these proteins are directly involved in the mechanisms of elimination of pathogens, the others finely regulate the activity of the former to avoid an autoimmune reaction.

3. The right answer is inflammation.

Inflammation is the body's stereotyped immune system reaction to external aggression (infection, trauma, burn, allergy, etc.) or internal (cancerous cells). Inflammation is a universal process, involving all tissues (called ubiquitous); it involves innate immunity as well as adaptive immunity.