The Neroun Reflex Arc The Brain Cerebrum: Responsible for thinking, speaking, memory, the 5 senses, etc Cerebellum: Responsible for balance and coordination Medulla oblongata: The most primeval part of the brain. Responsible for involuntary actions Disorders of the Nervous System
What are vaccines? Vaccines are substances that prepare the immune system to fight a disease-causing germ or other pathogen by imitating an infection. They trick the immune system into making a “memory” of that germ without ever having to fight the real germ in the first place. Now, when the immune system encounters the real pathogen — whether it’s a virus, bacterium or other microbe — it is ready to attack it. As a result, the vaccinated person doesn’t get sick. Vaccines do NOT cure, they prevent disease! Before vaccines, many children suffered from debilitating — and killer — illnesses such as measles, polio, smallpox and diphtheria. A simple scratch could be deadly if it became infected with the bacteria responsible for tetanus (or “lockjaw”). Vaccines, though, have changed this. Smallpox is completely gone from the world, and polio nearly so. Outbreaks of measles and diphtheria are rare, especially in the United States. Tetanus infections continue to decline worldwide. Vaccinations also can help protect people who can’t be vaccinated. These might be babies who are too young to receive a vaccine. Or there might be people who are too ill or too old to be vaccinated. When enough people in a community are vaccinated against a particular contagious disease, there’s little opportunity for that disease to spread from person to person. Doctors call this type of community protection “herd immunity.” How do vaccines work??? The body is designed to fight off foreign invaders. To do this, it needs to be able to distinguish elements of itself from outside agents (nonself). The immune system is always on the lookout for evidence of foreign stuff, or what scientists refer to as antigens in the body that don't belong. Antigens are found on cell surfaces and if they are foreign to the body will trigger an immune response. Antibodies which are produced by the bodies white blood cells, bind to antigens on foreign invader cells. Antibodies and antigens are very specific and fit together like a lock and key. For example the antigens on the flu virus are different then the antigens on the measles virus. Furthermore, different types of flu viruses may contain different antigens.
Vaccines can help to prevent against different diseases. Vaccines are made from either a weakened form of a pathogen or a dead/deactivated pathogen and are generally given by injection. Some never vaccines can also be given by mouth or as a nasal spray. The bodies immune system recognizes unfamiliar antigens and send out antibodies and other immune cells to stop and destroy the foreign invader. The antibodies "remember" the invader and this creates immunity against future infections with the same type of pathogen. This immunity happens because the next time that pathogen with the same antigens enters the body it is "remembered" and the specific immune response needed to destroy it is rapidly released. Some antibodies protect for a lifetime. Other times, the immune system’s memory of a germ can fade over time. When this happens, immunity can falter and leave a person vulnerable to infection. In these cases, the immune system needs a reminder. These reminders are called boosters. Tetanus is an example. Doctors recommend a tetanus booster every 10 years to maintain good immunity against the disease. Some germs also change substantially over time — evolve — creating new antigens. Influenza viruses are well known for doing this. Now the old antibodies may no longer recognize the new form of the germ (and antigens) and therefore fail to protect against it. That’s why flu vaccines must be given every year. Each new vaccine deals with the latest versions of these ever-changing viruses. |
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