Immune Health Basics: How Body Fights Infection

Have you noticed that people around you started sneezing again? So, how is your immune system? Are you ready for unexpected? And if you want to bulletproof your natural body defense, first, you should know immune health basics and how the body fights infection.

Overall, what do you know about your body defense?

Well, most people know little. And to build a healthy immune system, you should learn more about essential topics:

  • functions of the immune system
  • how the body fights viruses
  • the structure of the immune system
  • lines of defense in the immune system

Your robust immune system is your path to wellness. Besides, most people don’t know that the immune system as a part of your natural body detox.

So, join me on my journey to learn immune health basics.

1. System Protects Body Organs

Every hour of every day, foreign invaders–pathogens, viruses, harmful bacteria, and bad chemicals—are attacking you. Their goal is to enter your body and begin to multiply. As a result, the infection grows, and you start showing signs of illness.

Well, what does the body do?

Immune Health Basics: How Body Fights Infection

Natural Body Defense

By design, you have a system that protects body organs. It is your IMMUNE SYSTEM! (1)

But why most of us have a blurry idea about the immune health basics and how the body fights infection?

The reality is that in contrast to the cardiovascular system, for example, you cannot see the immune system. That is why, for a lot of people, the damage goes undetected.


Your life entirely depends on body defense! And if it fails, you are falling sick. Also, your immune system might have wear and tear. As a result, it can start attacking itself. Moreover, when the immune system is damaged, it can lead to severe diseases, for example, cancer.

It is critical to remember that the main function of your immune system is to Detect and Defeat the infection.

So, can you afford the weakened immune system?

How the Body Fights Viruses

But first, why are viruses invading your body?

Because they are not only multiplying but trying to dominate by killing cells and interrupting different cell functions. Besides, some bacteria make dangerous toxins for human cells or tissue. And this is how they fight for the ‘territory.’

Well, those foreign substances trigger your immune system activity—for example, fever or headache. Why? Because high temperature, for example, might destroy viruses. And this is how the body fights infection.

Well, if your body defense is active and healthy, the reaction is adequate. As a result, very soon you are back to normal. Well, is it another reason why you should know immune health basics and boost your immune system?  Also, how about regulating your kids’ immune system?

TAKEAWAY: The function of the immune system is to protect the body from foreign invaders. A compromised body defense is a base for all diseases.

2. The Structure of the Immune System

What are the parts of the immune system?

  • white blood cellsWhite Blood Cell Cartoon Character
  • macrophages (2)
  • antibodies
  • lymphatic system
  • bone marrow
  • spleen
  • thymus
  • complement system

Let’s give the honors to some heroes of your immune system.

White Blood Cells/Lymphocytes

White blood cells are your surveillance system. They patrol blood and tissue looking for foreign substances—viruses, parasites, microbes, or fungi. Then, they identify an invader and activate the immune attack.

There are different types of white blood cells, mainly B-cells, T-cells, and Natural Killer Cells or NKC. (3)

→ CLICK HERE to learn how to boost the activity of NK cells by up to 437%!


Antibodies fight foreign pathogens or their toxins. How does it work?

You will be very interested to know that each foreign virus or bacteria has a so-called ‘antigen’ on its surface. Besides, the same antigens are on chemicals produced by those microbes. Therefore, it works like a mark for the body surveillance that it is an outsider. And this is how antibodies identify those antigens for elimination.

Lymphatic SystemLymphatic System

We have covered before the topic of lymph and who it works, mainly because it is a significant organ of your natural body detox system.

Read more about lymph 101 in the post, “How to Detox Lymphatic System.

In short, the lymphatic system is made of:

  • Lymphatic vessels – channels carrying lymph fluids which deliver white blood cells;
  • Lymph nodes that ‘catch’ and ‘arrest’ foreign microbes
  • White blood cells

Reacting to pathogens is one of the lymphatic system’s critical functions.

Bone Marrow

Do you know why bone marrow is so crucial and why some people badly need a bone marrow replacement?

Well, this fantastic spongy part of your bone produces red blood cells that carry oxygen. (4)

TAKEAWAY: The immune system is a very comprehensive network of organs, fluids, and killer cells with one primary function to fight infection.

 Macrophage Engulfing Harmful Bacteria

3. Lines of Defense in the Immune System

It is crucial to emphasize that the body has a few lines of defense, specifically:

  • 1st Line of Defense – Innate defense, mainly physical and chemical barriers
  • 2nd Line of Defense – Non-specific defense (after pathogen entered the body)
  • 3rd Line of Defense – Specific or Adaptive Defense (5)

Let’s look at each line of defense in detail.

First-Line Defense Immune System


It is the primary physical barrier of the first line of immune defense against bacteria and other enemies. Sweat and oil—the sebum—protect the skin. In turn, it is shielding the body from millions of microorganisms.

Of course, the skin itself can also be infected, for example, when you have cold sore or athletes foot.

So, be sure you clean and detox your skin regularly. Healthy skin is not only beautiful, but it better protects you from infections.

Mucous membranes

They have a central role in releasing mucus and trapping bacteria. It contacts with skin in the area of eyes, lips, ears, or nostrils. In addition, when air with each inhale enter the lungs, mucus is crucial because of it warm and humidify the air.

Stomach acids, tears, saliva

These are chemical parts of the first immune defense line. Tears, for example, have antiseptic enzymes. Stomach acids, on the other hand, can kill dominant harmful bacteria.

TAKEAWAY: The first line of the body defense—physical and chemical—work as one outer protective network to stop pathogens and prevent they are entering the body.

Inflammation as Type of Immune Response

4. Types of Immune Responses: Inflammation

Second-line Defense Against Pathogens

When 1st line of immune defense has failed, bacteria is inside the body. How the body fights infection then?

It turns on the 2nd line of defense including:

  • inflammatory response – redness, healing, and heat
  • complement system helping to clear pathogens
  • releasing interferon to block the invader’s growth

Also, why is it called ‘non-specific?’

Well, because it is a non-specific response, the body has by design to fight different invaders and help to heal.

Let’s look more in detail at the inflammation. When last time did you have any injury, skin cut, or any other tissue damage? What did you feel first?

Inflammatory ResponseHow Body Fights Infection: Inflammation

It is ironic, but while writing this post, I have an inflated tissue injury of my foot.

Well, it is swollen and painful.

Also, I feel heat and pulse precisely in that spot. And it’s because the body sends the increased blood flow to an affected area.

Why pain? Because swelling stimulates the nerves!

Without a doubt, it is an infection. Well, it is a perfect example of the inflammatory response of the immune system – the classical case of how the body fights infection.

But why did I also feel some cramps in my leg muscle?

It is interesting to know that during inflammation, the body sends blood fluids to the injured area away from the vascular system. Well, make sense. As a result, I had muscle cramps.

TAKEAWAY: Body second defense line is non-specific to any particular pathogen. Inflammation is a primary non-specific response against infection.

Immune Health Basics: How Body Fights Infection. Macrophage Ingesting Pathogens
Source: Wikimedia. Credit: Obli

5. Third Line Defense Against Pathogens

Another critical point of the immune health basics. In contrast to the second line of defense, the third body defense line is specific to particular microbes or bacteria. And that’s why it’s called ‘adaptive’ defense. (6) (7)

But what it does is responding to antigens. These are the protein molecules on the invader cell membrane. (8)

Antigens are an important facet of how the body fights infection. Also, you should know that the immune system doesn’t recognize the body’s antigens. So, you are safe if your immune system is healthy.

Third Line Defense Illustration

Overall, the adaptive response to infection is a complex process. Below is a simple illustration of how immune cells activate this type of immune attack:

Immune Health Basics: How Body Fights Infection. Third Line of Immune Defense Illustration
Source: Wikimedia; Reh0318 [CC BY-SA 4.0 (]
  1. A macrophage—the immune cell—engulfs the pathogen.
  2. Macrophage digests the ‘invader’ and produces its antigens (orange triangle).
  3. T cells (yellow) attach to macrophage and become ‘activated’ T cells.
  4. The activated T cells bind to B cells (green) and get them ‘activated’.
  5. Some activated B cells become plasma cells (blue) and release in the blood, while other activated B cells become memory cells (purple). They will enable a response if there is a second invasion.
  6. Plasma cells produce antibodies (dark green Y-shape). In turn, they bind to antigens to fight foreign invaders.

So, rest assured that if this type of pathogens strike again, you are well-equipped with antibodies. (9)

TAKEAWAY: The third line of defense against the infection is specific to a particular foreign invader. The immune system responds to the pathogen’s antigen and produces antibodies.


In summary, your immune system is at the gate to protect you from outside dangers—diseases, pathogens, viruses, bacteria, fungi, and harmful chemicals.

In addition, there are three lines of body defense:

  1. External physical and chemical
  2. Non-specific and inherent
  3. Adaptive producing specific antibodies

So, now you know immune health basics, parts of the immune system, types of immune body defense and how the body fights infection.

Well, the next logical question is, how is your immune system?

And if you think it is in tip-top shape, great!

But remember that in contrast to other body systems, you cannot ‘see’ or ‘feel’ your body defense.

So, it is imperative to strengthen your body defense. Right?

Click here to get the best on the market supplements for the immune system.

I invite you to enlighten us with your thoughts. Leave them below.

Happy Fighting!

Immune System Sign


Founder of Detox Generation

Disclosure: The views and opinions expressed on this site are solely those of the author. All content, including text, images, and other formats, is for information purposes only. The author is not a medical professional, dietitian or integrative treatment specialist. Always seek the advice of your physician or other qualified health specialists with any questions you may have.

We are a website that needs compensation to operate like any other website on the internet. Our articles may include products that have been independently chosen and recommended by us. If you purchase something mentioned in the article, we may earn a small commission.