Types of Immunity and Components of Immune System - How Immune System Works

The immune system is a complex network of cells, tissues, and proteins that prevents germs like bacteria, viruses, parasites, and viruses from attacking the body and defends the body against infection. 
The immune system is an integrated system of vital processes performed by organs and cells inside the human body. 
The immune system identifies the causes and factors of the disease, such as harmful bacteria and viruses. Then this biological system expels and resists viruses, bacteria, and fungi that penetrate the skin or transmit to humans in multiple ways. 
When the immune system is functioning properly, it identifies a variety of threats, including viruses, bacteria, and parasites, and distinguishes them from the healthy tissues of the body.

What is the Function of the Immune System in the Human Body?

Types of Immunity and Components of the Immune System - How Does the Immune System Work?

What is the Immune System?

The immune system represents the body’s defense line against infectious organisms, germs, and other pathogenic microorganisms, through a series of steps, called immune response, thus maintaining overall health in the body and preventing infection. 

The immune system is essential to staying alive while providing recovery from disease and acquired long-term protective immunity under normal conditions.

The immune system consists of a network of special cells, such as: white blood cells - T-cells and B-cells, thymus gland, spleen, lymph nodes, stem cells, and antibodies, as well as a group of tissues and organs that work together to achieve the necessary protection.

Read more: Glands in Endocrine System and Mechanism of Hormone Action

Types of Immunity in the Human Body

There are three types of immunity in the human body, and they are as follows:

Innate Immunity: This is also called natural or native immunity and is present in the human body from birth, and provides general protection for the body as it extends protection to external parts, such as the skin, and mucous membranes.

Adaptive Immunity: This is called acquired immunity that the body acquires and develops continuously when exposed to the disease or immunized against them with vaccines. Adaptive immunity develops throughout a person's life.

Passive Immunity: Passive immunity is immunity borrowed from another source and lasts for short periods of time, as antibodies present in a mother's breast milk provide temporary immunity to diseases exposed to the mother.

Components of the Immune System 

 The immune system consists of a network of organs, cells, tissues, and molecules distributed throughout the body, which is responsible for protecting the body from harmful external bodies, such as germs and viruses, through the response of specialized white blood cells (WBCs),, which play a role in the immune response of the body, where they accumulate in the lymph nodes and other parts of the immune system. These organs include:

Bone Marrow: The bone marrow is defined as the spongy tissue that is located inside the bones in the body, including the hip and thigh bones. This marrow contains immature cells called stem cells. 

The bone marrow helps produce many types of red blood cells and white blood cells, which are essential for a healthy immune system and for fighting infections.

Lymphatic System: The lymphatic system consists of lymph nodes, such as those in the neck, including the tonsils, and lymph vessels that spread throughout all parts of the body. 

There is a liquid inside this vessel called lymph and is a clear white liquid consisting of water and nutrients.

This fluid delivers oxygen and food from the blood to the cells and takes from the cells the proteins that are synthesized in them and the products of metabolism and residues resulting from chemical processes to get rid of them after they are purified from the bacteria. 

The lymph moves from one place to another in the body depending on the movement of the muscles. Then these lymph vessels gather in larger vessels so that the fluid is treated inside the lymph nodes.

Lymph Nodes: Lymph nodes are defined as clumps of tissue that lie along the path of the lymphatic system, where these glands filter the lymph fluid before returning it to the blood and help prevent fluid build-up in the tissues, defend the body in case of infection, and maintain the normal size of blood and pressure in the body. They can be found in all areas of the body.

Tonsils: Tonsils are defined as a pair of soft tissue masses that are found in the pharynx, where each almond is made of tissue similar to the lymph nodes, covered with a pink mucosa.

The tonsils are part of the lymphatic system that helps fight infection, as the tonsils swell in response to an infection.

Adenoids: Adenoid, also known as pharyngeal tonsil or nasopharyngeal tonsil is a mass of soft tissue that is high up in the throat, just behind the nasal cavity. 

Like lymph nodes, adenoids are part of the lymphatic system and are made of lymphoid tissues. The lymphatic system removes infections and maintains body fluids.

Peyer's Patches: Peyer's patches, also known as aggregated lymphoid nodules, are an important part of gut-associated lymphoid tissue located throughout the ileum in the small intestine. 

Peyer's patches form an important part of the immune system by tracking the population of intestinal bacteria and suppressing the growth of pathogenic bacteria in the intestines.

Thymus: The thymus is a small, pyramid-shaped gland in the top portion of the chest, which lies below the breastbone at the level of the heart. The thymus is located in a region of the body called the mediastinum. 

The thymus is much more closely associated with the immune system than with the endocrine system. The thymus plays an important role in the training and development of T-lymphocytes or T cells.

Spleen: The spleen is the largest organ in the lymphatic system, and it is an important organ in maintaining fluid balance in the body. It consists of two different types of tissues; Red pulp tissues that filter blood and get rid of damaged and old red blood cells, and white pulp tissues that are immune cells that help the immune system fight the infection.

Digestive System: The digestive system helps protect the body from viruses, bacteria, toxins, and chemicals that are ingested, through lymphoid tissue, which is divided into three sectors:

The first sector consists of the tonsils, appendix, and lymph nodes located throughout the small intestine.

The second sector includes lymphocytes and plasma cells that feed the basement membrane of the small intestine.

The third sector that includes the lymphocytes that are located between the epithelial cells in the mucosa. The interaction between these cells in the lymphatic system is the primary factor of defense in the digestive system.

Skin: The skin is the largest organ in the body with an estimated total area of 1.85 square meters and its main function is to protect the body from microbes and harmful elements, and also helps in regulating body temperature and allowing the sensations of touch, heat, and cold.

Antibodies: White blood cells produce antibodies that are a series of protein molecules.

Hormones: Hormones can be defined as chemicals that are secreted by specific parts of the body known as the glands, and are followed in their classification into a device known as the endocrine system. 

In fact, the principle in the presence of hormones is based on achieving communication between the various parts of the body, as glands release these hormones into the bloodstream, and from the bloodstream, they are transmitted to the organs or tissues concerned. 

It is worth noting that hormones are considered to be very strong chemicals, so you see a small amount of them that have a great and very important effect on the body. 

It should be noted that hormones are not only released by the glands in humans but also, hormones are found in plants and animals and help each of them to perform their body functions correctly and accurately.

Read more: Hormone Interactions with Target Cells - How Do Hormones Control Your Life?

Immune System Features

➤The immune system responds to alien organisms by producing antibodies and stimulating specialized lymphocytes against specific antigens. This leads to killing these organisms and neutralizing the effect of any toxic products on them. 

➤The important immune system feature is to monitor the cells of the body to ensure that they are together and not abnormal.

➤The immune system is characterized by being fast to capture the latest developments in the body and works to prevent its spread and also eliminates non-good or damaged cells that cause cancer and other obstacles that contribute to harm to the organs inside the body, and therefore it is distinguished by its strength.

➤The immune system can identify countless pathogens, parasites, and foreign bodies that enter the human body.

➤The immune system contains enzymes that protect the body from infection with viruses.

➤The immune system contains defensive mechanisms that protect the entire body from germs.

How Does the Immune System Work?

A healthy person has defensive mechanisms that protect it from disease or the risk of infection. The role of the immune system is to protect against disease or its causes, which can be harmful. 

The most important function of the immune system is to monitor the cells of the body to ensure that they are together and not abnormal. 

The cells that infect viruses, malignant cells, and cells from another individual of the same type, all of these cells have protein markers on their outer membranes that act as a flag that declares their presence and as a signal to the immune system to destroy them.

The system to which these proteins belong is known as the major synthesis of tissue compatibility. 

The adaptive immune response is actually interactions of the immune system against compounds on the cell surfaces of the foreign organism that invades the body. 

These compounds are known as antigens and can enter the body through the skin or the respiratory and digestive channels and blood vessels. 

The most common antigens are in proteins such as those found in bacteria and viruses. This is a simplified idea of the immune system and it is the same function that it does for a normal individual or a pregnant woman.

How Immune System Fights Infection to Keep You Well

We can imagine that the immune system is an army defending its habitat from invaders. 

The defender is fortified through the skin, the corneal layer in the eye, the lining of mucus in the mouth, lungs, cells, and tissues in the intestine.

Not only that, but the secretions and fluids that are released from the body help push the germs out, and the enzymes available in that kill the germs. 

The secretions and fluids are eye tears, nasal mucus, and vaginal secretions. Therefore, any damage to the skin or these tissues, cell damage and defects in secretions and fluids expose the body to bacterial attack and ease of infection.

When the immune system can distinguish between healthy, damaged or malignant cells, this means that it works efficiently, but in the case of a weakened immune system, it will not be able to recognize enemies easily and therefore will not resist, or eliminate them. 

Therefore, the high incidence of diseases such as influenza and others is an indication of a weakened immune system. You should consult a doctor to find out the cause and its treatment.

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Author: Mahtab Alam Quddusi