The immune system is an arrangement of numerous cells, tissues as well as organs that work in tandem to protect our body against various diseases and infections. While continuous research over the years has helped scientists to understand various aspects and mechanisms of the immune system, currently they are continuing with studies to understand how our body zeroes in on assaulting micro organisms, infected cells and tumours, but do not affect the healthy tissues in any manner. In fact, an arrangement of latest technology and augmented genetic information possess the potential to reveal additional information regarding the manner in which our body shields itself from diseases and infections. This will, in turn, help the scientists to utilize the information obtained to prepare and adopt new approaches for preventing as well as treating contagious diseases and those related to the immune system.
It is worth noting here that the immune system is composed of special cells, tissues, organs and proteins. It also protects people against various germs and microbe all the time. In majority of instances, the immune system does a wonderful job by keeping infections and diseases at bay. As a result we remain healthy and robust. However, there are occasions when the immune system is also faced with problems and this can result in various ailments and infections.
It is said that the immune system is our body's defence mechanism against all contagious microbes and other foreign bodies that make us sick or suffer various health conditions. By means of a chain of steps known as the immune response, our immune system targets and eliminates these alien and harmful organisms and substances that assault our systems resulting in various types of health disorders.
There are three different types of immunity in humans and they are called adaptive, innate and passive.
As the term innate suggests, it is an inherited immunity. All individuals are born with an innate (also known as natural) immune system - which is the common protection possesses by humans. Several germs or micro organisms that adversely affect members of the other species usually do not cause any harm to humans. For instance, the viruses responsible for distemper in dogs or leukemia in cats actually have no effect on humans. It has been found that innate or normal immunity functions in both ways, as a number of viruses that are responsible for various ailments in humans, like the virus responsible for HIV/ AIDS, do not have any negative effect on dogs and cats.
In addition, innate immunity comprises the body's several external barriers, for instance the skin and mucous membranes - the ones that form the lining in our throat, nose and the gastrointestinal (GI) tract. These external barriers are considered to be the first line of defence of the body, as they prevent the microbes and diseases from going inside the body. When the barrier of this external defines system is broken, as in the instance of a cut or an injury, the skin tries to cure the break as early as possible, while the special immune cells present on the skin target and attack the assaulting microbes.
The second type of immunity is called the adaptive (active) immunity and this also helps to protect us from various diseases and health disorders. Unlike innate immunity, adaptive immunity increases all through our lives. This type of immunity develops when children as well as adults come in contact with various diseases or take vaccinations for immunization against specific diseases.
The third type of immunity, passive immunity is actually taken from an outside source and it endures for a very brief period. For instance, the antibodies present in the breast milk of a mother supplies the infant with temporary protection from diseases, which the mother has already been exposed to. Such passive immunity may be useful in protecting the infants from being infected during the initial period of their childhood.
It is worth mentioning here that the immune system of each individual is different. While it may appear that some people never get infections, there are others who seem to be falling ill every time. As we grow older, we generally become immune to additional germs, as our immune system is exposed to numerous diseases and pathogens during our life time. This is one reason why adults and teenagers seem to protect themselves against colds in a better manner than children. The body or the immune system of the teenagers and adults has been trained to identify as well as instantly attack several viruses that are responsible for colds.
Perhaps our immune system plays the most vital role in protecting us from the onslaughts of alien organisms and substances that may damage or increase the risks of homeostatis imbalance. In fact, the achievements of our immune system largely depend on how effective it is in differentiating between alien (outside) and host (self) cells. When any living being is threatened by microbes, viruses or carcinogenic cells, its immune system becomes active and provides protection from these detrimental substances. Usually, the immune system does not react against itself. Such absence of immune response is known as tolerance.
When any alien substance gets inside the human body our defence system immediately identifies it as a foreign matter. Our immune system employs a multifaceted "I.D". system to identify any foreign matter that has entered our body. Every cell in our body has a blend of sugars and proteins on its surface, which help to the immune system to identify the cells as "self". Foreign objects do not possess this identification, which the "self" cells have. The foreign object, on the other hand, posses other unique features, called antigens, which attach to the immune system identifiers known as antibodies.
This forms the foundation for the precise defence mechanisms when the body has developed the requisite antibodies for any particular antigen and the immune system will react more rapidly provided the body has not come in contact with the antigen earlier. In other words, this means your body is immune to the specific pathogen, since your immune system will react more rapidly in this case. More often than not, the non-specific section of the human immune system comprises phagocytes (also referred to as "eating cells"), which overwhelm as well as consume foreign matter such as bacteria and viruses that do not carry the specific identifiers of the body.