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What Organs & Tissues Are Involved In Immune Function?

What Organs & Tissues Are Involved In Immune Function?

The immune system is a complex bodily system designed to keep illnesses at bay. It acts as the body’s defense against pathogens and has three main functions: to fight off bacteria and viruses, to recognize harmful substances and neutralize them before they affect your health, and to fight changes in the body such as the development of cancer cells as a way to prevent disease.   

While many people are familiar with the immune system and what it does, not many may realize exactly what parts of the body are involved in the immunity process, or how all those parts function symbiotically to keep you healthy. So, what organs and tissues are involved in immune function and what are their specific roles?

Where is the immune system located?

The immune system is essentially located in various areas – it includes many different parts of the body. It is not in one set place, but rather involves several different components that all work together to ensure any pathogens that come your way are neutralized before they can do real damage.


Image by National Cancer Institute on Unsplash: A lymphocyte is a cell that can be created in two parts of the immune system: the bone marrow and the thymus. 


How many parts are there to the immune system?

Within the immune system, there are two subparts that work against disease: the innate and adaptive immune systems. The innate system is the one every human being is born with; it acts as a first responder when it comes to pathogens. When something potentially harmful enters the body, the innate system becomes activated to the threat. However, it does not know exactly what the threat is – only that there is one – so it prompts the start of the immune response while “waking up” the adaptive immune system to enact the next part of the process.

The adaptive immune system is designed to produce specific antibodies – specialized proteins to fight off specific pathogens. For example, if you come into contact with the influenza virus, your innate system sends out the call for the adaptive system to create antibodies to fight that specific virus. The cells that produce the antibodies are B-cells, otherwise known as B-lymphocytes. When these B-cells are created, the body can recognize that same flu virus if it happens to come into contact with it again in the future.

What body parts make up the immune system?

There are many body parts that play vital roles in the immune system. These include:

  • Skin
  • Bone marrow (spongy and soft tissues found within the cavities of bones)
  • The bowel (makes up the lower part of the digestive system)
  • The thymus (two lobes that connect behind the breastbone)
  • The spleen (an organ roughly the size of a fist found within the abdominal cavity)
  • Mucous membranes found in the genitals and bladder (lining the body’s cavities and organs)
  • Adenoids (a grouping of two glands in the back of the nasal passages)
  • Lymphatic vessels (blood vessels that carry blood containing immune cells to the organs involved in immunity)
  • Lymph nodes (small, bean-shaped organs found in various areas across the body, connected by lymphatic vessels)
  • Peyer patches (specialized lymphoid tissues found in the small intestine)
  • Tonsils (masses found in the back of the throat)

Each body part has a different role to play when it comes to immunity. Think of the immune system as a working line in a factory. There are many moving parts, and each is as important as the last for a proper immune response.

What are the main organs of the immune system?

While various organs throughout the body play an important role in immunity, the main organs are those that are part of the lymphoid system. The lymphoid organs are broken into two categories: primary and secondary. Primary lymphoid organs include the bone marrow and the thymus, and secondary lymphoid organs include the lymph nodes, spleen, tonsils, and mucous membrane layers. Each of these organs has its own role to play in immunity.

Bone Marrow

The bone marrow is a starting point for the immune system, in the sense that most of the immune cells needed to fight off disease and illness are create within the marrow itself. When the bone marrow creates these cells, it can then send them to other areas of the body such as organs and tissues.


Image by Jesse Orrico on Unsplash: Parts of the immune system can be found in many areas across the body.



The thymus acts like a gland, but it is technically an organ. Within the thymus, specialized immune cells known as T-lymphocytes are created. These cells are designed to target specific pathogens and often move freely throughout the body to help monitor cells for any changes (think of them as personal night watchmen for your body!). The thymus also helps to create the cells needed to regulate both the innate and adaptive immune response.

Lymph nodes

The lymph nodes are designed to filter out certain pathogens by trapping them. While they have the germs trapped, they activate the immune system to create specialized antibodies that hunt for specific pathogens.


The spleen has various jobs, such as storing immune cells until they are needed by the body. While it is storing cells, it also sends other cells (known as scavenger cells) to monitor and filter out germs that may get into the bloodstream.


The tonsils are needed for the immune system because they don’t only stop germs, but also contain a lot of the cells used to kill germs, known as white blood cells.

Mucous membranes

The mucous membranes in the bowel contain over half of the cells that create antibodies against specific pathogens. The cells within these membranes can target, mark, and destroy pathogens at the same time as using cell memory to allow them to recognize certain harmful substances if they’re encountered in the future.

Since there are so many parts involved in immunity, it’s easy to see why overall health plays a huge role in how well your body is equipped to fight off pathogens. While usually spoken about as if it were a singular entity, the immune system is actually a much larger and more complex system than many people believe.


Featured image by Public Domain Pictures on Pixabay

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