What Exactly Is Your Immune System?

Your immune system is made up of many different parts – both individual cells and proteins as well as organs and organ systems. The cells are things like your White Blood Cells (WBCs) and antibodies are proteins. The organs of your immune system are: skin, lymphatic system, tonsils, thymus, spleen, bowels, and bone marrow to name a few!

The First Line of Defense

Your first line of defense is your skin and mucous membranes (inside your lungs) – they create a physical barrier that prevents pathogens from entering your body. Think of them like the wall surrounding the castle! Breaks in your skin or membranes, such as a cut, allow pathogens to enter and can create an infection.

The Second Line of Defense

Your body’s second line of defense works in tandem with the first – things that enhance the physical barriers. These things are like the moat and boiling oil you send over your wall at the invaders at your doorstep.

Stomach acid stops most of the bacteria that enter our bodies through the food we eat. (It’s why keeping your stomach acid high is important!)

Mucus in our lungs help to trap the germs that we breathe in so we can expel them later. (Eww!)

Harmless bacteria living on our skin and mucous membranes also help to keep invaders out.

Antibacterial substances like enzymes in our saliva and airways help kill the germs that get past our initial defenses.

The Organs

The lymphatic system is composed of primary and secondary lymphoid organs. The primary consists of the bone marrow and thymus, and they make special immune cells call lymphocytes. These lymphocytes are responsible for your immune “memory.” Your lymphocytes can turn into T cells or B cells, so that when you are exposed to the same virus again, you can ramp up production of your army more quickly.

The secondary lymphoid organs are the lymph nodes, spleen, tonsils, and certain mucous membranes where the actual fighting occurs against the germs.

Bone marrow is where most immune cells are produced and multiply.

The thymus is behind your breastbone above your heart. It creates the T cells of your immune system, which are part of your innate and acquired immunity.

Your lymph nodes are nodules along the lymph vessels that act as filters to remove the pathogens, which is why they can become swollen and sore when you are fighting something.

Tonsils are near your throat and palate and can help stop germs from entering the nose and mouth. Like your lymph nodes, your tonsils can get swollen and sore when you are actively fighting an infection.

The spleen has several functions, but for your immune system, it is a storage facility for the immune system cells in your body.

Your mucous membranes also line your bowels and are responsible for making more than 50% of the antibodies in your body. They also have healthy gut flora, aka bacteria, that are along the lining. They are like the good plants in your garden – if you have a lot of good plants, there is less space for weeds (pathogens) to grow.