What Is The Immune System And What Does It Do?

Share with Friends & Family

What the immune system is and how it works became important to me when our son and young grandson both developed autoimmune disorders.

Our son was diagnosed with Celiac disease and our grandson was diagnosed with type 1 diabetes.

I became very curious about both of these diseases.

Once I learned they were autoimmune disorders it fueled my desire to learn more about the immune system itself.

Join me on this road to discovery as we learn about our immune system.

What is the immune system?

The immune system is the body’s defence against infections. It is made up of various organs, cells and proteins that all work together to attack germs and help keep us healthy. There are 2 main parts to the immune system and a source of temporary immunity.

The Innate Immune SystemWhat Is The Immune System And What Does It Do? - newborn

The Innate immune system is actually your very first line of defence that you are born with.

It includes such barriers as your skin and mucous membranes that keep harmful substances from entering the body.

Certain cells and chemicals that our immune system creates can also attack foreign substances.

The Acquired Immune System

The acquired immune system (also called adaptive immunity)develops when you are either infected with a virus or vaccinated against a virus.

Active immunity is usually long-lasting and for many diseases, it can last your entire life.

Passive Immunity

Passive immunity occurs when you receive antibodies to a certain disease rather than making them through your own immune system.

This occurs in newborn babies who receive antibodies from their mothers.

Passive immunity can also be received through blood products that contain antibodies.

The drawback is that passive immunity only lasts a few weeks or months.

When your immune system works properlyWhat Is The Immune System And What Does It Do? - vaccination

The immune system is very efficient and can tell the difference between your cells and those of a foreign substance and quickly activates, mobilizes, attacks and kills foreign invader germs that can cause you harm.

Your immune system learns the properties of different germs after you have been exposed to them. It will develop antibodies to protect you from those specific germs.

A perfect example would be when you get a vaccine your body will build antibodies to the foreign cells in that vaccine. It will remember these foreign cells and destroy them if you are exposed to them in the future.

Sometimes when we get sick, doctors may prescribe antibiotics to help our immune system. It is important to note that antibiotics only kill certain bacteria, they don`t kill viruses.

When something goes wrong

Sometimes your immune system can`t win an attack against an invader and you may develop an infection.

Other times your immune system launches an attack when there is no invader or it doesn`t stop an attack after the invader has been killed.

When this happens problems such as allergies and autoimmune diseases can occur.

This is how our young grandson got type 1 diabetes. His immune system attacked and killed the insulin-producing beta cells in his pancreas and he can no longer produce insulin.

Parts of the immune system

The immune system consists of a complex system of cells and organs that all work together to protect your body and help you recover when you get sick or injured.

White Blood Cells

What Is The Immune System And What Does It Do? - white blood cells

White blood cells are a key part of the immune system. It is their job to search for and attack and destroy germs in order to maintain good health.

There are many different types of white blood cells in the immune system. Each type either circulates in the bloodstream throughout the body or resides in a particular tissue waiting to be called into action.

Each type of cell has its own mission and its own way of recognizing a problem, communicating with other cells and performing its function.

Lymph Nodes

These are small glands that filter and destroy germs so they don`t spread to other parts of the body making you sick.

They are also part of your body`s lymphatic system. Lymph nodes contain immune cells that can analyze the foreign invader then activate, replicate and send the specific lymphocytes (white blood cells) to fight off that particular invader.

There are hundreds of lymph nodes all over your body, including your neck, armpits and groin.

Swollen, tender lymph nodes are a clue that your body is fighting an infection.


The spleen stores the white blood cells whose job it is to defend your body from foreign invaders. It filters your blood, destroying old and damaged red blood cells.

Tonsils and Adenoids

What Is The Immune System And What Does It Do? - tonsils

Tonsils and adenoids are located in your throat and nasal passage.

They can trap foreign invaders such as bacteria or viruses.

Our tonsils and adenoids have immune cells that produce antibodies that protect you against throat and lung infections.


The thymus is a small organ in your upper chest beneath your breastbone.

It is the job of the thymus is to mature a certain type of white blood cell.

The specific task of this cell is to learn to recognize and remember an invader so that it can be quickly attacked the next time this invader is encountered.

Bone Marrow

There are stem cells in the spongy center of bones that develops into red blood cells, plasma cells, a variety of white blood cells and other types of immune cells.

Bone marrow makes billions of new blood cells every day and releases them into the bloodstream.

Skin, Mucous Membranes and other first lines of defence

Skin is our first line of defence in preventing germs from entering the body.

Our skin produces oils and secretes other protective immune cells.

What Is The Immune System And What Does It Do?- mucous membrane

Mucous membranes line our respiratory, digestive, urinary and reproductive tracts. These membranes secrete mucous which lubricates and moistens the surfaces.

Germs will stick to the mucous in the respiratory tract and are subsequently moved out of the airways by little hair-like cilia.

We have tiny hairs in our noses that also catch germs.

There are enzymes in sweat, tears, saliva and mucous membranes as well as secretions in the vagina that will all defend your body and destroy germs.

Stomach and bowel

We all have stomach acids that kill many bacteria quite quickly after they enter the body.

Many types of good bacteria in our intestines actually kill harmful bacteria.

Symptoms of a weakened immune system

There are several deficiencies and disorders that can damage or disrupt the immune system.

Some types of medication actually make it harder for your body to fight infection.

High-stress levels

Did you ever notice how you tend to get sick after a major project at work or after a heavy exam schedule?

That is because stress is known to decrease the body’s lymphocytes, the white blood cells that help fight off infection. The lower your lymphocyte levels the greater your risk of contracting viruses like the common cold.

Frequent coldsWhat Is The Immune System And What Does It Do? - frequent colds

We catch colds from time to time and it is normal for adults to sneeze and sniffle through two or three colds each year. Most of us bounce back in 7 – 10 days.

It takes the immune system 3-4 days to develop enough antibodies to fight off those pesky germs.

However, constantly catching colds, or having a cold that just doesn’t seem to be running its course is a clear sign that your immune system is struggling to keep up.

Stomach troubles

Frequent bouts of diarrhea, gas or constipation could be a sign that your immune system is compromised.

According to research, nearly 70% of your immune system is actually located in your digestive tract. There are many beneficial bacteria and microorganisms living there whose job it is to defend your gut from infection and support the immune system.

Having low amounts of these helpful gut bacteria can increase your risk of viruses, chronic inflammation and even autoimmune disorders.

Slow-healing wounds

Did you know that whenever you get a cut, scrape or burn your skin goes into damage control?

Your body actually works to protect the body by sending nutrient-rich blood to the injury to help regenerate new skin.

Naturally, this healing process will depend heavily on healthy immune cells.

But, if your immune system is compromised, then your skin can’t regenerate.

This means your wounds take much longer to heal and this increases your risk of infection.

Frequent infections

According to The American Academy of Allergy Asthma & Immunology, battling frequent infections could be an indicator of a weakened immune system.

Signs of a weakened immune system can include:

  • more than four ear infections within one year
  • developing pneumonia twice within one year
  • chronic or more than three episodes of bacterial sinusitis in one year
  • requiring antibiotics more than twice a year

Extreme tiredness

If you know you are getting enough sleep each night yet still suffer from exhaustion your immune system may be trying to tell you something.

When your immune system struggles, so do your energy level.

This is because your body is trying to conserve energy to fuel your immune system so it can fight off germs.

Fighting germs takes a lot of energy so it doesn’t leave much for other tasks.

Immune system Disorders


Sometimes our bodies overreact to harmless substances (such as food or pollen) and the immune system launches a response.
When this happens the body fights the allergen by releasing histamines that cause allergy symptoms.

Allergic reactions can range from mild (sneezing and stuffy nose) to severe anaphylactic reactions (breathing problems and death).

There are over-the-counter antihistamine medications that can help calm the symptoms.

Anaphylactic reactions may require an epi-pen.

Autoimmune DisordersWhat Is The Immune System And What Does It Do? - type 1 diabetes supplies

Autoimmune disorders occur when the immune system mistakenly attacks its own healthy cells.

There are several well known autoimmune disorders such as:

Primary Immunodeficiency Disorders

Primary immunodeficiency diseases are inherited (passed along genetically within families) disorders.

There are over a hundred of these diseases that prevent the immune system from working properly.


Two very well-known infections that weaken the immune system are HIV and mononucleosis


There are certain types of cancer that directly affect the immune system. Those types of cancer would be leukemia, lymphoma and myeloma. These types of cancer occur when immune cells uncontrollably grow.


Sepsis occurs when your immune system overwhelmingly responds to an infection. Your body`s response to the infections actually triggers widespread inflammation and causes a downward spiral of events that can often lead to organ damage, organ failure or death.


Certain medications, such as corticosteroids, can weaken the immune system.

It is common for transplant patients to take immunosuppressant medications in an effort to prevent transplant rejection. The downside is that these drugs can also increase your risk of infection.

How to boost your metabolism

We are aware that our body requires nourishment, adequate rest and a healthy environment in order to remain strong and healthy and the immune system is no different.

Certain lifestyle choices have been proven to boost immune systems and help avoid illness.

There are steps we can take to help boost or maintain a healthy immune system including:

  • quit smoking
  • lose weight or maintain a healthy weight
  • limit alcohol consumption
  • adequate sleep
  • regular exercise
  • frequent handwashing
  • limit stress and focus on wellness
  • ensure you are up to date on all vaccines

When to call a doctor

What Is The Immune System And What Does It Do? - see a doctor

If you have a cold that doesn`t seem to go away or you find you are always sick you should see your doctor.

Some symptoms indicative of a possible autoimmune disease can include:

  • exhaustion or fatigue (always feeling tired)
  • sore, aching muscles (especially when unaccompanied by fever)
  • difficulty concentrating or paying attention
  • loss of hair
  • inflammation, redness or rashes anywhere on your body
  • tingling or numbness in fingers or toes

Final thoughts

Through this article we’ve gained a more thorough understanding of what is the immune system and what does it do.

The immune system is a complex system of organs, cells and proteins whose job is to protect us from infections and viruses.

Whether inherited or acquired, our immune system works very hard to protect us.

Our immune system, like the rest of our body, requires a healthy nutritious diet, regular exercise and enough sleep in order to functions at its best.

Sometimes our immune systems are weakened and we get sick other times it malfunctions and causes autoimmune disorders.

It is important to seek medical advice if we have a persistent cold (won’t go away) or get colds frequently as this could indicate a weakened immune system.

I am not in any way a medical practitioner. Please do not rely on the information on our website as an alternative to medical advice from your doctor or another healthcare provider. We only share our experiences. We are affiliates, this means that if you purchase something from a link or ad on this site we may receive a small commission. This in no way affects the price you pay. 

Do you or someone you know, struggle with an autoimmune disorder?

Perhaps you know someone with a primary immunodeficiency disorder?

What measures do they take to help improve their immune system?

Leave your answers in the comment section below and please share any tips that work for you.


Medex Supply - Better Prices for Better Quality

Share with Friends & Family

2 thoughts on “What Is The Immune System And What Does It Do?”

  1. Our body is really a wonderful machine, the way it all works, the way different organs and tissues work together as a well-organized team, it’s impressive. It was interesting to see where and what different functions there are. My allergies are super light and have decreased considerably over the years, maybe because I do my best to follow a healthy diet? Who knows, but I’m happy about it. I have only one dangerous allergy: vaccinations. I cannot get vaccinated, because it will cause very strong allergic reactions in me. I’ve been through one such reaction already and I don’t want to go through that again.
    It was interesting to learn that diabetes type 1 can be acquired because your body attacks the insulin-producing beta cells. It’s worrisome to read that sometimes your body – like a machine – can mess things up and with negative consequences …

    • Thanks for dropping by Christine. I agree, it truly is fascinating how all the parts of the body work together to keep us functioning as we should. Making healthy lifestyle choices will certainly help our body do its job most effectively. I have never heard of being allergic to vaccinations. All the more reason to make healthy choices in life to give your body a helping hand. I have one potentially life-threatening allergy and that is to bee stings. I carry 2 epi-pens for that. I am also allergic to codeine and morphine both of which are commonly prescribed pain-killing drugs. I certainly hope I never require surgery because I don’t think there is much they can give me that doesn’t contain at least traces of one of those. Yes sometimes things go wrong with our immune system and people can get type 1 diabetes-like our grandson or Celiac like our son. All we can do is make healthy choices and deal with the hand we are given. Thanks again and take care.


Leave a Comment