Episode #7 of the course “How the human body works”
The immune system is the body’s natural defense against disease, infection, and parasites. Many organ systems come together to support the body’s immunity, and medical science has found ways to enhance the body’s defenses with a range of supplements and treatments. Everything from the mucus that lines your trachea and bronchi to the white blood cells that fight infection, and even your skin (your largest organ), all are part of your body’s natural defense system against outside invaders.
To become “immune” to the effects of a bacteria or virus—the microorganisms that cause many diseases—means a person is no longer affected by that disease. People become immune to diseases through exposure to them. As a body learns how to fight off invaders, the body’s systems become better fighters the next time they encounter that invader. When a baby is born, its body has no experience with invading bacteria or viruses, which is why infants are susceptible to infection.
One part of the immune system that helps a person’s body keep “memories” of the diseases it has learned to fight are specialized cells called antibodies. These antibodies travel the bloodstream after a person fights off a disease, ready to defend the body if they encounter the disease again. Antibodies can destroy microorganisms by poisoning them, consuming them, or damaging them. Babies are born without antibodies, and for the first six months of their lives, they use the antibodies in their mother’s milk. At six months old, a baby begins to develop their own immune system.
Medical professionals help people develop immunity to diseases through a process called “vaccination” or “immunization.” Injecting a small amount of the disease or antibodies into a person’s bloodstream helps the body prepare to fight that disease. Immunizations have recently become somewhat controversial, but scientific research shows that they are one of the best ways to help protect against life-threatening diseases.
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