Immune System
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5 tHE Immune SYSTEM
What is Immune System?
5.1 Immune system is the capability of the body to fight against any alien viral, bacterial, fungal or cellular attack. You constantly come in contact with many pathogens like bacteria and viruses that have the potential to make you ill. When the body’s non-specific defences are unable to overcome an invading organism, the body’s immune system goes to work. Rather than being an organ system, it works by using components of the lymphatic and circulatory systems. Nature has developed this highly complex and wonderous inborn defence mechanism to fight against any viral, fungal, bacterial or cellular attack. Nature has gifted the body to develop antibodies for shooting away or resisting infections by foreign bodies through this strong immune system.
Immune System Categories
5.2 The immune system can be broadly divided into three categories: –
(i) Innate or Natural Immunity – This is something that everyone is born with and is a general protection that human beings have. Innate immunity includes the external barrier – the skin – and mucous membranes (those that line the throat, nose and gastrointestinal tract) which are the first line of defence. If the outer defensive wall is broken, be it a cut or gash, the skin attempts to heal it quickly and special immune cells on the skin attack invading germs. Another form of natural immunity is “passive” or “borrowed” immunity. Despite being naturally present in the body, it traces its source outside the body. For example, antibodies (defensive proteins) present in mother’s milk provide an infant with temporary immunity to diseases that the mother had been exposed to. This can help protect the infant against infection during early years of childhood.
(ii) Adaptive or Acquired Immunity – This is something that individuals develop over the years. When our body gets infected, it induces antibodies on its own or sometimes with the help of medication and vaccination to fight the infection. It is most likely that the same infection will not recur. This is due to the memories these antibodies have. That is why if you have chicken pox in your childhood, chances are you will not get it when you are an adult. In other words, the antibodies induced during the first infection restart their fight if the same virus enters the body again. But then what about viruses that cause the regular cough, cold and fever? How do they recur inspite of having been cured by the antibodies before? That is because viruses are very smart! They tend to mutate and every time they enter the body, they do so in a somewhat new form. That stops the previous antibodies from recognising and fighting against them.
(iii) Artificial Immunity – This is similar to adaptive immunity, though of course, it is a little more permanent in nature. This immunity develops with the help of single or multiple vaccinations. Each dose develops a certain amount of antibodies in the system that help fight various infections and in due course create a permanent wall against them. Diseases like influenza, diphtheria and small pox fall in this category.
