How The Immune System Works: Overview

2023 Author: Lynn Laird | [email protected]. Last modified: 2023-05-21 21:10

In recent months, we have been making steady efforts to face the ordeal of the coronavirus pandemic. Since there is no cure for COVID-19, we can only rely on our immune system. A real weapon of the body, the immune system's mission is to protect us against various pathogens and infections. For various reasons, it can weaken making the body vulnerable to external aggressions and diseases. It is therefore essential to strengthen your immunity. First of all, one must understand how the immune system works and the definition of immunity.

How the immune system works: what is the immune response?

The immune system is our defense mechanism. To cope with infections and diseases, the immune response is activated. Moreover, our immune system sets up two types of response: innate immunity and adaptive immunity. Both occur when one or more antigens foreign to our body have been identified.

Innate immunity

When an infectious agent enters the body, an immediate response is triggered. This process alerts the entire organism and triggers a mobilization of effectors to the site of infection. This is called an "innate immunity" or the first mechanism of the immune system in the face of attacks. It is she who detects intruders and eliminates them.

Adaptive immunity

Sometimes innate immunity is not enough to prevent microorganisms from invading the body. Consequently, a second immune response is triggered. It may take approximately 96 hours for the adaptive immune response to develop. It is important to know that our immune system recognizes the antigens present and directs its defense mechanisms directly towards them. What is special about adaptive immunity is its ability to memorize attacks. This means that with each new exposure to a pathogen already encountered, the body's defense systems will react faster and more strongly.

Functioning of the immune system: effector agents

The effectors of the immune system are either cells (leukocytes) or free molecules that are able to move throughout the body. Its agents are responsible for carrying out general surveillance and regrouping at the site of infection if necessary. It is very important that the effectors communicate with each other to trigger the most suitable immune response.

Leukocytes

Leukocytes, also called sans white blood cells, are cells circulating in the blood that are the main effectors of an immune response. They are the ones who detect any foreign body that has entered the body and have several physicochemical actions to destroy them.

Lymphocytes (small white blood cells found in the blood and the lymphatic system) are formed by lymphoid stem cells. Lymphocytes are, in fact, the cells which attack viruses, bacteria and other foreign invaders, and which, among other things, play the most important role in the immune response. The so-called “T” lymphocytes, also called “T cells”, are more specifically involved in the monitoring of the body's cells. They destroy damaged and infected cells and tell so-called “B” lymphocytes to make antibodies. B lymphocytes make antibodies to help fight infection and disease. “B” cells can also remember invaders that have already been fought. Therefore, once the intruder is detected,B cells react very quickly by making more antibodies to help fight it.

Antibodies

B cells make proteins that turn into plasma cells. These are the antibodies, also called immunoglobulins. These circulate in the blood and their role is to fight infections and defend the body against harmful foreign substances. To do this, a specific antibody binds to a specific antigen (foreign substances, for example germs), such as a key that only opens a lock. This means that only the antibody produced to fight a specific antigen can bind to it. When this happens, the white blood cells can find and destroy the intruder that is causing the infection or disease.

The lymphatic system

The lymphatic system plays an essential role for the proper functioning of the immune system and the body. It is made up of a large network of lymphatic vessels, as well as specific organs. Lymphatic vessels, on the other hand, are arranged parallel to certain blood vessels and are present in many tissues of the body. Each vessel connects tissue to a lymphatic organ. The lymphatic organs are, for their part, primary (the bone marrow and the thymus - ensure the production of lymphocytes) and secondary (the lymph nodes and the spleen - ensure the differentiation and proliferation of lymphocytes). Lymph is the body fluid, containing white blood cells, nutrients and wastes, which is within the lymphatic system. The amount of lymph is between 1 and 2 liters.

The lymphatic system is essential for the immune system to ensure the body's defense. It is the lymphatic organs that ensure the production of lymphocytes, and it is the lymph that transports them in the lymphatic network. In addition, the lymph contributes to the detoxification of the organism, because it drains certain excess fluids from the tissues. Finally, but just as important, the lymph contributes to the circulation of nutrients and hormones essential to the body.

Spleen

The spleen is the largest of the lymphatic organs. It plays a determining role in the functioning of the immune system and in the process of blood cell renewal. The role of the spleen is to filter and purify the blood. It mainly deals with the destruction and recycling of used red blood cells. It also acts as a blood reserve for the body.

Thymus

The thymus is a lymphoid organ, located at the base of the neck, in the upper part of the thorax. The thymus is one of the centers of production and maturation of immune cells, T lymphocytes. Without T cells, our bodies are not protected against infection and cannot effectively control abnormal cells (for example, cells. cancerous). When this organ is not functioning properly, it can lead to an insufficient number of T cells to protect us. The thymus gland also makes hormones that help T lymphocytes to grow and therefore the immune system to continue to function properly.

What weakens the immune system?

Once we have explained how the immune system works, let's learn why the body's defense weapons are sometimes unable to protect us.

Having healthy immunity is not only a guarantee of health, but also of life! Without an immune system, our body leaves us defenseless and unarmed against external aggressions. When he is healthy, no infection can resist him. But there is a "but" to all of this. There are many factors that can upset the immune system. The destruction of the defenses exposes the organism to serious infections, cancers etc. When it comes to a weak immune system, the culprits are in most cases:

• An illness

• A dietary imbalance

• Sedentary lifestyle or overtraining

• Stress

• Lack of sleep

• Aging

1. Thanks to a complex ecosystem, the gut is a centerpiece of the immune system. A poorly balanced diet, either in quantity or in quality, is the most important and most common cause of immune deficiency. For example, the lack of micronutrients, vitamins and minerals, leads to immune aging and a decrease in the proliferative capacities of T lymphocytes, which makes the body more vulnerable to microbes.

2. It is clear that physical exercise, in addition to contributing to overall good health, also has a direct effect on immunity. It improves blood circulation, helps increase cell immunity and decreases the risk of infection.

Conversely, overtraining has a negative impact on the body. It causes a drop in the level of lymphocytes and, consequently, less antibodies in the event of attacks.

3. Lack of sleep is one of the most harmful factors for health. Sleeping too little has a direct impact on the immune system, reducing the body's resistance to infections. As a result, cells make fewer antibodies. Chronic lack of sleep is harmful to both physical and mental health.

4. The link has long been made between stress and reduced immune defenses. Chronic stress, in particular, is bad for immunity because, according to the study by researchers at Ohio State University, it reacts directly to genes in white blood cells, leading to blood cell reactions. exacerbated defense. Therefore, this inordinate immunity could increase the risk of diabetes, cardiovascular problems, and obesity.

5. Aging also weakens the immune system. As we age, the body partly loses its ability to identify foreign antigens. Therefore, autoimmune diseases are becoming more common. T cells react less quickly to antigens. Older people have less complement protein and do not produce as much in response to bacterial infections. Finally, with age, the ability of antibodies to bind to antigen is reduced.

How to strengthen your immune system ?

Fortunately, there are ways to optimize your immune system and strengthen your defenses.

The food is crucial for a healthy immune system. It is very important to have a varied diet adapted to the seasons. It must also be balanced in proteins, carbohydrates and lipids. It is advisable to reduce the intake of foods high in sugar and to avoid saturated animal fats and excess animal protein. Conversely, you should prefer unsaturated fats, containing essential fatty acids: virgin oil from 1st pressing, rich in omega 3 - from rapeseed, flax, walnut or camelina; cold sea fish such as anchovies, sardines, mackerel. It is very important to increase the share of vegetables and fruits. Fibrous foods (semi-complete or whole grains, legumes, vegetables and fruits) are also essential.

The probiotics are recommended to stimulate the immune system as a whole and, in particular, the integrity of the intestinal cells. You can get it in organic stores or pharmacies. Regarding food, it is found in lacto-fermented foods or sauerkraut.

The vitamin D is not only important for bones, but also for the functioning of the immune system. It activates T lymphocytes. So sun exposure should not be overlooked. During the period from October to April, you can supplement your vitamin D needs with food supplements.

The magnesium stimulates white blood cells and has an anti-fatigue action, which could be very useful in the fight against stress. To obtain it in sufficient quantities, it is necessary to favor foods that contain it (cocoa, coffee, dark chocolate with 70% cocoa, cashews, almonds, spices, whole breads and rice, tofu, seafood, sardines in oil, snails etc.).

Vitamin C deficiency is one of the causes of weakened immunity. It is not synthesized by the body, therefore, it must be provided by food or by supplementation.

The echinacea acts as a stimulator of the body's defense system and helps fight colds. This plant is therefore preventive and curative at the same time. Please note: there are contraindications for people with autoimmune disease or diabetes.

Mushrooms from the Asian pharmacopoeia - shitake, maitake and reishi - help to strengthen the immune system, to better resist epidemics as well as to cope with stress. Warning: given the high concentration of mushrooms, you must first consult a health professional to find out how much to take.

Reducing chronic stress is key to healing your weakened immunity. Yoga, gardening, reading, outings or meals with friends: everyone has their own way to relax. What matters is to regain your emotional balance.