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What Is The Immune System?

The immune system is a complex network of organs, cells, and proteins that defends the body against infection while protecting the body's own cells [2].

It works to detect and eliminate harmful substances, such as pathogenic microbes and toxic substances, using both innate and adaptive mechanisms, which distinguish self from non-self [1].

The innate immune response acts rapidly and broadly, providing physical and chemical barriers, as well as cellular defense mechanisms, to neutralize and destroy invaders. On the other hand, the adaptive response produces long-lived cells that can re-express effector functions, contributing to immune memory [1].

Self-tolerance is important in avoiding harmful effects on self-tissues. Failure of self-tolerance leads to autoimmune diseases [1]. The cells involved in the adaptive immune response include B cells and T cells, which work together to recognize and eliminate specific antigens [3]. B cells produce antibodies that recognize and neutralize the antigen, while T cells can either directly kill the antigen or activate other immune cells to do so.

The immune system has two main arms of defense: innate immunity and adaptive immunity. Innate immunity is the first line of defense and offers lifelong protection against invaders [2]. Adaptive immunity is acquired during one's lifetime through exposure to specific antigens and can retain long-term memory to enable faster response upon re-exposure [1]. The two arms of defense work together to protect the body from harm caused by pathogens.

The immune system is a complex and vital system that protects the body from harmful substances and pathogens. It uses both innate and adaptive mechanisms to distinguish self from non-self and to eliminate harmful substances. Failure of self-tolerance leads to autoimmune diseases. The two main arms of defense, innate and adaptive immunity, work together to provide lifelong protection against invaders and enable faster response upon re-exposure. [1][2][3]


[1] Overview of the Immune Response - PMC

[2] Immune system explained

[3] Innate vs Adaptive Immunity

what is the immune system?