APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -Your skin and mucous membranes are the first line of defense against germs entering from outside the body. They act as a physical barrier with support from the following: Antibacterial substances can kill germs right from the start.

Detailed explanation-2: -If an antigen enters the body and B-cells recognize it (either from having had the disease before or from being vaccinated against it), B-cells will produce antibodies. When antibodies attach to an antigen (think a lock–key configuration), it signals other parts of the immune system to attack and destroy the invaders.

Detailed explanation-3: -The immune system responds to antigens by producing cells that directly attack the pathogen, or by producing special proteins called antibodies. Antibodies attach to an antigen and attract cells that will engulf and destroy the pathogen. The main cells of the immune system are lymphocytes known as B cells and T cells.