Innate Immunity and Acquired Immunity, Immunologic Memory

Immune System Fundamentals


Now let's take a look at the innate immunity, acquired immunity concepts as well as , immunologic memory and the immune system organs. So, what is immune ? first, an example:

As I have mentioned before, I like to compare the immune system with an anti-virus software on the computer. First because it works silently on the background and we don’t even notice its presence unless it does not work or if it reacts to an external attact, for instance, when you cut yourself.

When your computer does not have anti-virus software or if it is shut down or out of date, just like when something dies, it is invaded by all sorts of enemies. None of these happen when the anti-virus is working perfectly and up to date otherwise it is like an open door. Exactly like when we die, only slower! When we die, our immune system is gone!No need to describe the picture!



Luckly, the immune system is intelligent and complex enough to sort out all substances and organisms telling apart the harmful ones.

So, mother nature is very impressive! think about this: Although there are many potentially harmful pathogens, none of them can invade or attack all organisms because a pathogen's ability to cause harm requires a susceptible victim, and not all organisms are susceptible to the same pathogens. For instance, the virus that causes AIDS in humans does not infect animals such as dogs, cats, and mice. Similarly, humans are not susceptible to the viruses that cause canine distemper, feline leukemia, and mouse pox.




Where does this intelligence come from?

It depends on what type of immune system we are talking about. There are two types: innate and adaptative immunity

(slow down here and review at the end to make sure you understood it! i found it particularly overwhelming at first)



a) innate Immunity, occurs naturally as a result of a person's genetic constitution or physiology and does not arise from a previous infection or vaccination.It is Also called genetic immunity, inherent immunity, native immunity, natural immunity, nonspecific immunity.

It is you natural protection after all...

It includes two parts: humoral and cellular

One part, called humoral innate immunity, involves a variety of substances found in the humors, or body fluids. These substances interfere with the growth of pathogens or clump them together so that they can be eliminated from the body.

The other part, called cellular innate immunity, is carried out by cells called phagocytes that ingest and degrade, or "eat'' pathogens and by so-called natural killer cells that destroy certain cancerous cells. Innate immunity is non-specific, that is to say, it is not directed against specific invaders but against any pathogens that enter the body.



b) acquired immunity, a vertebrates additional privilege and more sophisticated system of defense mechanisms, that can recognize and destroy specific substances.

It is conferred after contact with a disease; and artificial immunity after a successful vaccination. Also named specific immunity, resistance or specific resistance.The defensive reaction of the adaptive immune system is called the immune response.

Any substance capable of generating such a response is called an antigen, or immunogen.

Antigens are not the foreign microorganisms and tissues themselves; they are substances, such as toxins, in the microorganisms or tissues that the immune system considers foreign memory.

Immunologic memory is the ability of the adaptive immune system to mount a stronger and more effective immune response against an antigen after its first encounter with that antigen, leaving the organism better able to resist it in the future.

Once again, it is a team work! Adaptive immunity works with innate immunity to provide vertebrates with a heightened resistance to micro organisms, parasites, and other intruders that could harm them. However, adaptive immunity is also responsible for allergic reactions and for the rejection of transplanted tissue, which it may mistake for a harmful foreign invader.






Didn’t I say the immune system was a network? Yes I did! You may be confused now! I would be!

Think about it: “immunity x immune system”. innate immunity and acquired immunity are a roles played by the immune system which consists of a group of organs (and some tissues).
The organs of your immune system are positioned throughout your body.

Most of them are called lymphoid organs because they are home to lymphocytes -the white blood cells that are key operatives of the immune system. Within these organs, the lymphocytes grow, develop, and are deployed.

Bone marrow, the soft tissue in the hollow center of bones, is the ultimate source of all blood cells, including the immune cells.

The thymus is an organ that lies behind the breastbone; lymphocytes known as T lymphocytes, or just T cells, mature there.

The spleen is a flattened organ at the upper left of the abdomen. Like the lymph nodes, the spleen contains specialized compartments where immune cells gather and confront antigens.

In addition to these organs, clumps of lymphoid tissue are found in many parts of the body, especially in the linings of the digestive tract and the airways and lungs--gateways to the body. These tissues include the tonsils, adenoids, and appendix.

for a complete discussion of each one of them, click on "Immune Organs"

Do Not Get Scared With The Terminology!

i'm adding here this video for those who prefer something more visual...

whatch out for the vocabulary - terms may vary but we are still talking about the same thing!





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