How the immune system works #2

Our immune system is essential for our survival. Without an immune system, our bodies would be open to attack from bacteria, viruses, parasites, and more. It is our immune system that keeps us healthy as we drift through a sea of pathogens.

 

Immunity

Everyone's immune system is different but, as a general rule, it becomes stronger during adulthood as, by this time, we have been exposed to more pathogens and developed more immunity.

That is why teens and adults tend to get sick less often than children.

Once an antibody has been produced, a copy remains in the body so that if the same antigen appears again, it can be dealt with more quickly.

That is why with some diseases, such as chickenpox, you only get it once as the body has a chickenpox antibody stored, ready and waiting to destroy it next time it arrives. This is called immunity.

There are three types of immunity in humans called innate, adaptive, and passive:

 

Innate immunity

We are all born with some level of immunity to invaders. Human immune systems, similarly to those of many animals, will attack foreign invaders from day one. This innate immunity includes the external barriers of our body — the first line of defense against pathogens — such as the skin and mucous membranes of the throat and gut.

This response is more general and non-specific. If the pathogen manages to dodge the innate immune system, adaptive or acquired immunity kicks in.

 

Adaptive (acquired) immunity

This protect from pathogens develops as we go through life. As we are exposed to diseases or get vaccinated, we build up a library of antibodies to different pathogens. This is sometimes referred to as immunological memory because our immune system remembers previous enemies.

 

Passive immunity

This type of immunity is "borrowed" from another source, but it does not last indefinitely. For instance, a baby receives antibodies from the mother through the placenta before birth and in breast milk following birth. This passive immunity protects the baby from some infections during the early years of their life.

 

Immunizations

Immunization introduces antigens or weakened pathogens to a person in such a way that the individual does not become sick but still produces antibodies. Because the body saves copies of the antibodies, it is protected if the threat should reappear later in life.

 

Immune system disorders

Because the immune system is so complex, there are many potential ways in which it can go wrong. Types of immune disorder fall into three categories:

 

Immunodeficiencies

These arise when one or more parts of the immune system do not function. Immunodeficiencies can be caused in a number of ways, including age, obesity, and alcoholism. In developing countries, malnutrition is a common cause. AIDS is an example of an acquired immunodeficiency.

In some cases, immunodeficiencies can be inherited, for instance, in chronic granulomatous disease where phagocytes do not function properly.

 

Autoimmunity

In autoimmune conditions, the immune system mistakenly targets healthy cells, rather than foreign pathogens or faulty cells. In this scenario, they cannot distinguish self from non-self.

Autoimmune diseases include celiac disease, type 1 diabetes, rheumatoid arthritis, and Graves' disease.

 

Hypersensitivity

With hypersensitivity, the immune system overreacts in a way that damages healthy tissue. An example is anaphylactic shock where the body responds to an allergen so strongly that it can be life-threatening.

 

In a nutshell

The immune system is incredibly complicated and utterly vital for our survival. Several different systems and cell types work in perfect synchrony (most of the time) throughout the body to fight off pathogens and clear up dead cells.

 

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Source: https://www.medicalnewstoday.com/articles/320101.php