Immune system

Function: The function of the immune system is to help keep your body healthy and to make sure you don't get sick. 

Organs:
Skin: Your skin is the first thing that the bacteria and the viruses have to get through and the skin protects your body from all of the germs that try to enter.
White blood cells: Your white blood cells work to get rid of any viruses that somehow gt into your immune system.
Nose: Your nose works to trap all of the bacteria that gets past your skin so that the bacteria doesn't get into your bloodstream.
Stomach: Your stomach helps because if the bacteria gets in your food and into your body your stomachs acids will help break down the bacteria
Phagocytes: They work to eat and get rid of he bacteria that gets in your blood stream and that is making you sick.
Tonsils and lymph nodes: They work together to help get rid of the bacteria to help fight off invading germs.

There are many more that do important jobs for the immune system as well. Some others are your spleen, appendix, bone marrow, etc.
Other systems:
The Systems that the Immune system works with is the circulatory system. Your circulatory system is the system that gets infected by bacteria because the blood is part of the system. The circulatory system transports all of the white blood cells to fight off the bacteria. The immune system helps keep the circulatory system safe while having the circulatory system transport your white blood cells to help. The circulatory is very important to the immune system. Your immune system also works with the digestive system because the digestive system breaks down some of the bacteria that gets in your body.
Analogy:

https://upload.wikimedia.org/wikipedia/commons/d/d2/Soldiers_of_the_205th_Afghan_National_Army_Corps.jpg

The immune system is like soldiers because:

• Both of their jobs is to protect something 
• When something bad happens they both have to fight the enemy off
• They body is like the country that they are fighting for because they are both important 

The immune system and soldiers are similar because they both are very important to something big. Both of their main jobs is to protect something. When ever something bad happens they have to fight it off like how the soldiers have to fight when there is enemy's or a war and your immune system has to fight off sickness. They both have to protect something that is important like how the immune system protects your body and soldiers protect their country.

Structure and function:
The main function of the skin is to make help make sure no bacteria gets into your body. The skin is make just to do this.
1. The skin is make to be stretchy so that you can move because if it was hard or not stretchy you would not be able to move very well or your skin would tear.
2. Your skin is on the outside of your body because if it were on the inside it would not be able to protect your body it would let all of your insides be exposed to bacteria.
3. Your layer of skin is thin because it allows it to be stretchy. If the skin was too thick you could not move as much and your skin would be very hard. If your skin was any thinner than you would get hurt a lot more and it would be easier for bacteria to get in your system.

  Sources:
https://www.brainpop.com/health/bodysystems/immunesystem/

http://kidshealth.org/en/kids/ismovie.html