Role of the Immune System

The immune system is the body’s defense mechanism against harmful pathogens, including bacteria, viruses, and foreign bodies.
It comprises various cells, tissues, and proteins that work collaboratively to protect the body.
The key components of the immune system include white blood cells (leukocytes), antibodies, the complement system, and lymphatic system.
The primary function of the immune system is to distinguish between the body’s own cells and foreign cells or substances, and to eliminate the latter.
Leukocytes play an essential role in the immune system by identifying and destroying pathogens. There are two main types: phagocytes, which consume harmful bacteria, and lymphocytes, which remember and recognize previous invaders.
There are two types of immunity provided by the immune system - innate (natural) immunity and adaptive (acquired) immunity.
Innate immunity refers to the defenses that are present at birth. These include barriers such as the skin and mucus membranes, which block entry of pathogens.
Adaptive immunity, on the other hand, is the immunity one develops throughout life as exposure to diseases or vaccination triggers immune responses.
The adaptive immune system comprises B-cells and T-cells. B-cells produce antibodies that bind to antigens to neutralize them, whereas T-cells destroy infected cells in the body.
When the immune system recognizes a foreign substance, it launches an immune response. This includes the production of antibodies, specialized proteins that bind to specific antigens on pathogens.
An important aspect is its ability to remember specific pathogens, allowing for a faster and more effective response to subsequent exposures to the same pathogen. This is known as immunological memory.
A healthy immune system can prevent most common diseases and infections. However, in immune deficiencies, the body’s capacity to fight off pathogens is impaired.
The immune response can be boosted by vaccines, which train the immune system to recognize and eliminate specific pathogens.
Although the immune system is crucial for health, it can sometimes cause problems, such as allergies, where the immune system overreacts to harmless substances, and autoimmune diseases, where the immune system mistakenly attacks the body’s own cells.

This summarises the primary roles of the immune system in human health and disease prevention. Review this periodically to cement understanding and recall.