Antigens are little molecules that are able stimulate an immune response. Each antigen has distinct surface features, resulting in different responses. Antibodies are Y-shaped cells produced by B cells of the immune system. These antibodies connect like a lock on to antigens which is the key.
First line of defense
A Pathogens is a microorganism that causes diseases or illness. The main three types of pathogens are viruses, bacteria and fungi. A pathogen can also infect unicellular organisms from all of the biological kingdoms.
Second Line of defense
A B-cell is a cell in the immune system that make antibodies invade pathogens such as viruses. They form memory cells that remember the pathogen for faster antibody in future infections so that the illness can be cured quicker.
The First line of defense are the main surfaces barriers that are ready and prepared to defend the body from infection. These include skin, tears, mucus, stomach acid, urine.
The second line of defense is made up of general responses to infection. The immune system responds to different pathogens. For example it triggers an increase in core body temperature to produce a fever. This can help fight different parts of a pathogens by doing things to stop them.