What Is the Immune System? - Our Body's Defense Against Pathogens

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  • 0:46 The Immune System
  • 2:39 Innate and Adaptive Systems
  • 4:13 How the Two Systems…
  • 5:57 Immune Tolerance
  • 6:58 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

In this lesson, you will be introduced to the immune system. You'll learn about the innate and adaptive immune system, Edward Jenner, haptens and immune tolerance.

Your Private Security Force

If you've ever heard of the company Blackwater, then you're familiar with the concept of a private military or private security force. Governments, companies and individuals hire these private forces for their own use and protection. Your own body has a very similar private security force made up of many different factors, which work together to protect and serve against foreign invaders that are trying to kill you. This security force is so large that it is subdivided into many different parts, two of which will be covered in this lesson.

The Immune System

Before we continue with this lesson, an introduction must be made to the founder of your private security detail. His name is Edward Jenner, and he was an English physician who is known as the father of immunology. Jenner developed the very first vaccine, and his work led directly or indirectly to billions of lives being saved around the world.

The security force Jenner is the founder of isn't called Blackwater, it's called the immune system. This is a collection of organs, tissues, cells and molecules that protect against pathogens. The organs and tissues of the immune system can be thought of as the buildings your security forces need to use to protect you. The cells are the individual security guards inside those buildings, those patrolling the roads between buildings and those on the front lines. While the molecules are the guns, bullets and communication systems the private force uses to protect you.

On the front lines, there are pathogens your security forces protect against. Pathogens are everything from parasites to fungi to bacteria to viruses and even haptens, which are molecules that may cause an immune response when attached to a protein but not on its own. A famous example of the latter is a substance called urushiol that is found in poison ivy.

Regardless, the pathogens your little soldiers fight against are sometimes really small, such that a few little soldiers can kill them off, and sometimes really big, to the point of needing an entire squadron or platoon of soldiers to be sent to kill the invader.

The Innate and Adaptive Immune System

As I mentioned before, there are many different groups and subgroups of your security firm. It's a really big organization, one that probably costs hundreds of thousands of calories per year to maintain and keep the soldiers well fed.

There are two main divisions of your private force. The first is called the innate immune system. This is the first line of defense against pathogens, also called the non-specific immune system. Basically, this is a large contingent of barriers (like skin) and soldiers (or cells) that is always on the front lines, always patrolling, always shooting anything and anyone on-sight. They're not specific. They don't pick and choose whom to kill. They just shoot to kill without thinking. If it moves, they will attack it! They also react very quickly and are present almost all over your body at all times.

This is in contrast to the other large section of your immune system called the adaptive immune system. This is an immune system specific to an antigen and generates immunological memory. In essence, this part of your security force isn't the army soldier patrolling the streets, killing any intruder on site with a fast response, as the soldiers of the innate immune system are trained to do. No. Here it's a bit different. The soldiers of the adaptive immune system are like the Special Forces.

How the Two Systems Work Together

These Special Forces lag a bit behind in the fight against an invader because they take a long time to train and a while longer to deploy in comparison to the regular soldiers already on the front lines. However, they're specially built and trained to target very specific invaders. Once they are trained to kill that specific invader, they never forget them because they have a very good memory. In the future, if that particular invader were to attack your body again, the Special Forces would be able to be mobilized much more quickly because they no longer have to be trained for that invader after the first attack, and therefore, they will remember how best to defend your body right away.

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