Immunology:
       The immune system is a remarkably adaptive defense system that has evolved to protect
the host from invading pathogenic microorganisms and cancer. This system is as important as
a country's defense forces such as army, navy and airforce. This immune system generates
a variety of cells and molecules capable of recognizing the pathogens(bacteria, virus etc) and
destroy them. These cells are ubiquitous in our body and acts as soldiers in a war and protect
our body.
       I will try to share whatever I know about this system in future and make it as simple as
possible so that it is easier for perusal. If you do find any errors, please feel free to let me know.
You will be surprised to know how our body reacts to simple ailments like common cold,
allergies to major complications like cancer. There is a lot of activity and tremendous energy
consumption during such ailments. I will try to add some animated gifs to show how these
reactions are occur in our body.
Chapter 1:
         Our body has 2 major defense system.
                1. Innate Immunity: This type of non-specific immunity is the basic resistance to diseases
                                              that an individual is born with.
                2. Acquired Immunity: It is a specific immunity which is acquired later in life when the
                                               individual faces new pathogens in life. It is a constant process acquired
                                               throughout his life. So you can expect your grandfather at the age of
                                               80 still fighting with new pathogens, although the efficiency is reduced.
Innate Immunity:
      This can be otherwise referred to as Non-specific immunity. Like an army having soldiers, tanks,
and other different levels of weaponery, it possess 4 main barricades viz anatomic, physiologic, phagocytic
and inflammatory. Let's see one by one.
Anatomic barriers: These are present right from the embryo stage in a mother's womb. You will be
                             surprised to know how some parts of your body act like soldiers. Skin-it is the
                             most effective mechanical barrier.As long the skin is intact, you can be sure of getting
                             these pathogens out of your body. It has a acidic environment which retards growth
                             of microbes. This acidic environment is created by the oily secretions in our body. So
                             next time if you see someone with more oily secretions you can be sure that he has good
                             barrier.JKiddin!!.It might be pathological too.Mucous membrane-it is present inside our
                             body and also in our bodily orifices like mouth, nose, genital openings etc.They secrete
                             some viscus fluid called mucus which helps to discard the microbes. Now we know, why
                             we get increased mucus (called as phlegm) when we have cold. It basically traps the microbes
                             and gets it away from our system. So make sure you spit out or sneeze out the mucus when you
                             have common cold. J.
Physiologic barriers: Temperature, pH, oxygen tension, and certain soluble factors(molecules) in the blood. Body
                             temperature in chickens prevent them from acquiring certain diseases like Anthrax.MIf humans
                             get anthrax--well there are several symptoms ranging from fatal to chronic suffering. But one
                             common suffering is that you will be sterile!!.yes!. affected persons cannot reproduce.Solube
                             factors like interferons, some enzymes kills the microbes which gets into the blood circulation.
Phagocytic barrier: Some cells in our body called as macrophages engulf these microbes and digest them. Normal
                             cells can take up these by a process called endocytosis.
Inflammatory barrier: What happens when you cut or damage your skin? 4 signs start up immediately
                             1. Rubor (redness): yes the reddish tinge in the bruised area is caused by the rush of blood supply
                                  to that particular place. Blood has to flow more to that area inorder to give more nutrition, oxygen
                                  some specialised cells called monocytes, neutrophils, soluble factors like interferons etc to protect
                                  that site.
                             2. Tumor (swelling): swelling of that site occurs due to surge of fluid from the cells, and increased
                                  permeability from the blood.
                             3. Calor (heatness): If you are careful enough , you can notice the rise of temperature in that site alone.
                             4. Dolor (pain): L Ofcourse, there will be some pain in that site of infection or damage because of the
                                   certain substances like histamines, etc and also due to the damage of pain receptors in that area
                                   these will relay signals to brain and you will feel the pain.
 

Next chapter : Acquired Immunity.