What is the role of each of the three lines of defense of the human body?

The first line of defense is the human body's ** and mucous membranes, which mainly directly block bacteria, viruses and other harmful substances from entering the body;

The second line of defense is the body's macrophages.

i.e. white blood cells. The main function is to remove foreign substances such as bacteria and viruses that have entered the human body, and can remove the remains of aging and dead cells in the body; Both lines of defense are non-specific immunity, i.e., they are not targeted.

The third line of defense refers to the body's immune function, including humoral immunity and cellular immunity. Humoral immunity is also called antigen-antibody immunity, that is, the reaction of plasma cells to release antibodies to accumulate antigens; Cellular immunity is T cells.

It acts on the target cells that are invaded by viruses and so on, causing them to be lysed and digested, so as to achieve the purpose of destroying the host cells of the virus. This line of defense is specific immunity.

The human body has three lines of defense:

The first line of defense is composed of ** and mucous membranes, which can not only block pathogens from entering the human body, but also their secretions (such as lactic acid, fatty acids, stomach acid and enzymes, etc.) have a bactericidal effect.

The second line of defense is germicidal substances in body fluids and phagocytes.

These two lines of defense are the natural defense functions gradually established by human beings in the process of evolution, which are characterized by the fact that all human beings are born with them, and they do not target a specific pathogen, but have a defensive effect against a variety of pathogens, so they are called non-specific immunity (also known as innate immunity).

The third line of defense is mainly composed of immune organs (thymus, lymph nodes, spleen, etc.) and immune cells (lymphocytes).

The third line of defense is the acquired defense function gradually established by the human body after birth, which is characterized by being produced after birth and only acts against a specific pathogen or foreign body, so it is called specific immunity (also known as acquired immunity).

Acquired immunity - the third line of defense for immunity.

The third line of defense for immunity: specific immunity.

It is mainly immunized by immune cells - lymphoid B and lymphoid T cells.

Among them, lymphocytes are "responsible" for humoral immunity; Lymphoid T cells are "responsible" for cellular immunity.

The acquired specific immune system is a specific immune mechanism, and the antibodies secreted by immune lymphocytes produced against one antigen can only exert immune function against the same antigen. It has no effect on variants or other antigens.

The first line of defense is like the antivirus software itself; The third line of defense is like a virus Trojan that kills software.

Only when the three lines of defense play an immune, complete and intact role can our health be more fully guaranteed.

1. The human body has three lines of defense against the attack of pathogens. It is the first line of defense composed of ** and mucous membranes and their secretions, and the bactericidal substances in body fluids (such as lysozyme) and phagocytosis make the scattered cytosis into the second line of defense, mainly composed of immune organs and immune cells to form the third line of defense.

2. The three lines of defense to protect the human body itself The human body is like a city, with both external and internal defense lines.

The three lines of defense of the human body refer to the different ways in which we protect the body from the external environment in our lives, which are mainly divided into the following three aspects.

First line of defense: **. The human body** is the outermost protective shell, which not only protects against the invasion of external microorganisms, but also regulates body temperature and protects against UV radiation.

At the same time, our ** can also alert us in a variety of ways, such as feeling pain, temperature changes, touch, etc., so that we can take timely measures to avoid injury or infection.

The second line of defense: the immune system. The body's immune system is an important line of defense within our body, and it can produce antibodies to defeat viruses or bacteria in time when we are susceptible to them.

The immune system protects us from various diseases while also providing us with longer-lasting protection.

The third line of defense: healthy habits. By maintaining healthy lifestyle habits, we can better maintain the health of our bodies.

For example, maintaining a good diet, getting enough sleep, exercising reasonably, and avoiding bad habits such as smoking and drinking alcohol can make our bodies healthier and stronger.

In conclusion, the three lines of defense of the human body are important barriers to protect our body from the external environment. We should pay attention to protecting these three lines of defense, maintain good health through good living habits, and create better conditions for our life and work.

The first line of defense of the human body is composed of ** and mucous membranes, which can not only block pathogens from entering the human body, but also their secretions (such as lactic acid, fatty acids, gastric acid and enzymes, etc.) also have a bactericidal effect. The second line of defense is germicidal substances in body fluids and phagocytes. These two lines of defense are the natural defense functions gradually established by human beings in the process of evolution, which are characterized by the fact that people are born with a specific pathogen, and do not have a defensive effect against a variety of pathogens, so they are called non-specific immunity (also known as innate immunity).

The third line of defense is mainly composed of immune organs (thymus, lymph nodes, spleen, etc.) and immune cells (lymphocytes, a type of white blood cell). The third line of defense is the acquired defense function that the human body gradually builds up after birth, which is produced after birth, and only acts against a specific pathogen or foreign body, so it is called specific immunity (also known as acquired immunity).

People lack the old body, and the three acres of people are the big line of defense.

The third line of defense is specific immunity (also known as acquired immunity).

(1) The first line of defense of the human body is composed of ** and mucous membranes, which have the effect of blocking and killing pathogens and cleaning foreign bodies (2) The second line of defense of the human body is composed of bactericidal substances and phagocytic cells in body fluids, which has the effect of dissolving and phagocytosing pathogens (3) The third line of defense of the human body is composed of immune organs and immune cells, which can produce antibodies and destroy antigens, which belongs to specific immunity.

The first and second lines of defense belong to non-specific immunity, also known as innate immunity, which is not against a specific pathogen, but has a defensive effect on a variety of pathogens Non-specific immunity is immunity that everyone is born with and has a defensive function against a variety of pathogens; However, the specific immunity of Yuanshujian is acquired by human beings, and it only works against a specific pathogen or foreign body, which is also called acquired immunity, so the answer is: (1)**; Mucous membrane; Blocking, killing pathogens, cleaning foreign bodies (2) sterilizing substances in body fluids; Phagocyte; dissolves and phagocytoses pathogens (3) immune organs; immune cells; production of antibodies, destruction of antigens; multiple pathogens; non-specific immunity; Congenital Immunity Orange Pants; a specific pathogen, foreign body; Specific immunity, acquired immunity.

First line of defense: **.

The second line of defense: the immune system.

The third line of defense: the specific immune system.

One: ** and cilia.

Two: phagocytic cells, bactericidal substances.

Three: immune organs and immune cells.

** and bactericidal substances in mucosal humors and lysozyme immune organs and immune cells.

1.and mucous membranes.

2.Bactericidal substances in body fluids and phagocytes.

3.Antibodies produced by immune organs and immune cells.