The purpose of the immune system is basically the defense of the human body as it terminates the antigens which are the foreign things that come into our body and it also recognizes previous invaders which helps the body destroy it quicker.

The immune system is like the military or army of the body because a military is used in warfare so they fight against invaders in their home country sometimes while the immune system usually destroys the invaders of the body. The T cells in your body is like an army because it is the one that fights the invaders and destroys them. The B cells are like the military’s intelligence because they lock on to the targets (the invaders) and sends the defenses towards them. The skin is like barb wire electric fences because enemy invaders have trouble getting past it. Thymus is also like a recruiter who recruits soldiers for the army which are the T-Cells.

Parts of the immune system are the white blood cells that originate from the bone marrow. The white blood cells or leukocytes are divided into phagocytes which eats the alien intruders and lymphocytes which allow the body to remember previous intruders and thus helps the body to destroy them. Kinds of phagocytes are the neutrophil and there purpose is to fight off germs. There are also different kinds of lymphocytes such as B-cells that produce the antibodies which are proteins which target the antigens. The antibodies when produced stay in the body so if the same antigen comes back the antibodies will lock on to it again immediately and have T-cells help destroy it. The antibodies also help in neutralizing toxins and complement antibodies help with fighting off bacteria and other harmful substances. T lymphocytes destroys antigens that have antibodies on them or kills infected cells.

Another part of the immune system is your skin which prevents diseases from entering the inside of your body which makes it your body’s first line of defense. Also if the layer of skin has been breeched by being cut special cells attack incoming germs and heals the cut. A special antibacterial material comes from your skin which lets your body stay mold free because most bacteria and spores die when in contact with your skin.

Thymus is a part of the immune system that produces the T-Cells which destroy the antigens in your body or infected cells. This makes the part important when a baby but when you reach adulthood you don’t need a thymus to live but it is still valuable for maturation for T-Cells.

Spleen is another important part of the immune system because it checks the blood for foreign cells or old red blood cells. People without spleens generally become more sick than a person with a spleen.

Bone marrow’s purpose in this system is to create red and white blood cells so without it we would have no blood cells or white blood cells.

The lymph system basically is blood plasma in your body and it bathes cells with water and nutrients. It also drains and filters the inter cell fluids to remove and bacteria in them.

The immune system is divided into three categories which is innate immunity which is your body’s natural defense against germs and it protects us from germs that harm other species. The skin is in this category because it is our first line of defense against foreign substances being a barrier between germs and our bodies. Adaptive immunity involves lymphocytes that remembers previous diseases that were exposed to us which gives us an immunity over them which is how vaccinations work where they send a small weak version of a disease into you so your body will have an immunity to it. Passive immunity is temporary defense against diseases from a source such as a mother’s breast milk that a baby drinks which gives him/her immunity in early childhood.

Your immune system basically works with different lines of defense against antigens. Your first line of defense which is the skin usually prevents germs from entering your body but germs and other things can go through your nose or mouth. If the antigen gets into your body your second line of defense which is the white blood cells. The B-Cells lock on to the germ and tells your T-Cells to attack and chew it up. Your antibodies also target cells and the T-Cells attack antigens with antibodies on it and if poisons enter your body then your antibodies neutralize the poisons. The complement antibodies help fight infections.

Your immune system is very important because it protects your body from foreign material like bacteria, viruses, etc. So if a person’s immune system did not work they’d die quite quickly considering your body has no defense whatsoever against things like the cold which can turn into pneumonia and kill you. So you wouldn’t have skin which makes it easy for germs to enter your body and you have no antibodies or white blood cells to fight germs that entered your body. So without the immune system you’d die shortly especially if you were young.

The most important part of the system is probably the white blood cells because they are responsible for remembering previous diseases and build an immunity for those diseases and fight off bad substances that enter your body. So in comparison to only having the skin, if you only have the skin you’d have protection against germs but if germs go through your mouth or nose you have no defense against those germs and they would kill you. Though bone marrow and your thymus are needed to make T-Cells and other white blood cells so you need almost every part to make to make the body run smoothly but white blood cells are the most important/