However, the lack of resistance means that there are not enough defensive troops to protect the body, so that the enemy is unable to grasp it, and the body tends to decline. Causes of low immunity include inborn physical problems, infections, and the aftermath of chemotherapy. The immune system's combat strategy In addition to the immune system, in fact, our skin and mucous membranes are the most basic defense tools of the body. Physical, chemical, and biological foreign invasions will be immediately blocked by the skin; bacteria and viruses entering from the nasal cavity will be wrapped in nasal mucus , and excreted by cilia; bacteria entering from the mouth, gastrointestinal mucosa and ciliated cells are responsible for sticking and expelling. Suspended particles inhaled from the respiratory tract are larger
than 2.5 micron, and we can stick to them, popular database cough or spit, etc., and directly expel them from the respiratory tract, but if the particles are smaller than 2.5, or even carcinogens, invade the respiratory tract and enter the The blood, lymph, and tissue systems can only activate the immune system to deal with it. When the immune system fights against invading substances, it will send lymphocytes with different functions to fight against the characteristics of the invading virus. For example, "macrophages" that engulf invaders, "T cells" that cannot phagocytose cancer cells and dying cells, but can directly fight and destroy foreign objects, "B cells" that fight viruses by producing antibodies, and "
B cells" that can decompose and allow cell membranes Rupture, and then clear out the "natural killer cells" of mutated cells or dying cells. In addition, in addition to signaling warnings, lymphocytes also remember which viruses and bacteria have invaded. When they encounter the same virus or bacteria again, they must produce antibodies or deal with them by other cells, which are "immune memory cells". Under normal conditions, our immune system will protect the body according to the above "strategy", but if you suffer from cancer and undergo chemotherapy, it is likely that the problem of low immunity will occur.