These elements interact with each other and aim to defend the body against diseases, viruses, bacteria, microbes and others.
The human immune system serves as a protection, a shield or a barrier that protects us from unwanted beings, the antigens, that try to invade our body. Thus, it represents the defense of the human body.
Immune Response
The process of defending the body through the immune system is called the immune response.
There are two types of immune responses: innate, natural or non-specific, and acquired, adaptive or specific. Learn about each type of immune response in the explanations below.
Innate, natural or non-specific immunity
Innate or natural immunity is our first line of defense. This type of immunity is born with a person, represented by physical, chemical and biological barriers.
See the table below to see what they are and how they act to defend our body.
| Barrier | Action on the organism |
|---|---|
| Skin | It is the main barrier the body has against pathogens. |
| Eyelash | They help protect the eyes, preventing the entry of small particles and in some cases even small insects. |
| Teardrop | It cleans and lubricates the eyes, helping to protect the eyeball from infections. |
| Mucus | It is a fluid produced by the body that has the function of preventing microorganisms from entering the respiratory system, for example. |
| Platelets | They act in blood clotting, which, in the face of an injury, for example, they produce a network of threads to prevent the passage of red blood cells and retain the blood. |
| Saliva | It contains a substance that maintains lubrication in the mouth and helps protect against viruses that can invade the organs of the respiratory and digestive systems. |
| gastric juice | It is a liquid produced by the stomach that helps in the process of food digestion. Due to its high acidity, it prevents the proliferation of microorganisms. |
| Sweat | It contains fatty acids that help the skin prevent fungi from entering the skin. |
Innate immunity is also represented by defense cells, such as leukocytes, neutrophils and macrophages, which are described below.
The main mechanisms of innate immunity are phagocytosis, release of inflammatory mediators and protein activation.
If innate immunity does not work or is not sufficient, acquired immunity comes into play.
Acquired, adaptive or specific immunity
Adaptive immunity is the defense acquired throughout life, such as antibodies and vaccines.
It consists of mechanisms developed to expose people with the aim of developing the body’s defenses. Adaptive immunity acts in the face of a specific problem.
Therefore, it depends on the activation of specialized cells, the lymphocytes.
There are two types of acquired immunity:
- Humoral immunity : depends on the recognition of antigens, through B lymphocytes.
- Cellular immunity : defense mechanism mediated by cells, through T lymphocytes.
Cells and organs
The human immune system is made up of different types of cells and organs, which are divided as follows:
Find out below how each of these cells and organs act to defend the body.
Cells
The body’s defense cells are leukocytes, lymphocytes and macrophages.
Leukocytes
Leukocytes or white blood cells are cells produced by the bone marrow and lymph nodes. Their function is to produce antibodies to protect the body against pathogens.
Leukocytes are the main agent of our body’s immune system.
Leukocytes are:
- Neutrophils : surround diseased cells and destroy them.
- Eosinophils : act against parasites.
- Basophils : related to allergies.
- Phagocytes : perform phagocytosis of pathogens.
- Monocytes : penetrate tissues to defend them from pathogens.
Lymphocytes
Lymphocytes are a type of leukocyte or white blood cell, responsible for recognizing and destroying infectious microorganisms such as bacteria and viruses.
There are B lymphocytes and T lymphocytes.
Macrophages
Macrophages are cells derived from monocytes. Their main function is to phagocytose particles, such as cell debris or microorganisms.
They are responsible for initiating the immune response.
Organs
The organs of the immune system are divided into primary and secondary immune organs.
Primary immune organs
Lymphocytes are produced in these organs:
- Bone marrow : soft tissue that fills the inside of bones. Site of production of blood cells, such as red blood cells, white blood cells and platelets.
- Thymus : gland located in the thoracic cavity, in the mediastinum. Its function is to promote the development of T lymphocytes.
Secondary immune organs
The immune response is initiated in these organs:
- Lymph nodes: small structures formed by lymphoid tissue, which are located along the path of the lymphatic vessels and are spread throughout the body. They filter the lymph.
- Spleen: filters the blood, exposing it to macrophages and lymphocytes that, through phagocytosis, destroy foreign particles, invading microorganisms, red blood cells and other dead blood cells.
- Tonsils : made up of lymphoid tissue, rich in white blood cells.
- Appendix : small lymphatic organ, with a large concentration of white blood cells.
- Peyer’s patches : accumulation of lymphoid tissue that is associated with the intestine.
Low immune system
When the immune system does not function properly, it decreases its ability to defend our body.
This makes us more vulnerable to diseases such as tonsillitis or stomatitis, candidiasis , skin infections, ear infections, herpes, flu and colds.
To strengthen the immune system and avoid problems with low immunity, special attention must be paid to what you eat. Some fruits help to increase immunity, such as apples, oranges and kiwis, which are citrus fruits. The intake of omega 3 is also an ally for the immune system.
It is also important to exercise, drink water and sunbathe in moderation.
