It is our natural shield against external aggression.
It is our body’s defense system against foreign agents.
The immune system is made up of different organs, cells, and proteins that work together. They circulate in our body through the circulatory and lymphatic systems to recognize outside invaders such as viruses, bacteria, parasites, fungi, pathogens and infected cells, and then activate the necessary defenses to eliminate them.
Our immune defenses are naturally alert and ready to intervene in an emergency, putting in place the necessary countermeasures to defend the body and keep it healthy.
HOW DOES IT WORK?
When the body senses foreign substances (called antigens), the immune system works to recognize the antigens and get rid of them. It relies on lymphocytes (a particular type of white blood cell), which can be of two types:
T lymphocytes (or T cells), are produced by the thymus and directly attack the antigen (a substance foreign to the body) by binding to it through receptors; they are called “killer cells” and “eating cells” and belong to our innate immune system whose main job is to fight harmful substances and germs that enter the body, for instance through the skin or digestive system.
B lymphocytes (or B cells), belong to our adaptive immune system. They are produced by the bone marrow and release antibodies (special types of proteins) into the blood that have a complementary form to the antigen and bind to it, neutralizing and destroying it.
The immune system attacked by an external agent can provide two responses:
PRIMARY RESPONSE – when the organism first comes into contact with the pathogen;
SECONDARY RESPONSE – Once the body has come into contact with a disease-causing germ for the first time, it usually stores information about the germ and how to fight it. Then, if it comes into contact with the germ again, it recognizes the germ straight away and can start fighting it faster. In fact, the immune system maintains a “memory” (memory lymphocytes) that can last a lifetime, making the organism immune and in case of a second infection, the memory lymphocytes react with rapid production of lymphocytes and antibodies that prevent the disease.