Which of the following is NOT a component of the immune system?

The immune system is a complex network consisting of various components that work together to protect the body against pathogens, such as bacteria, viruses, and other harmful invaders. The components of the immune system include organs, such as the spleen and thymus; tissues, such as lymphoid tissue; and processes, which include immune responses like inflammation and the activation of immune cells.

Muscles, while essential for movement and other functions in the body, do not play a direct role in the immune response. They are not involved in the production or action of immune cells, nor do they facilitate the communication between these cells. Therefore, muscles are not considered a component of the immune system. Understanding these distinctions helps clarify the specific roles of different body systems and how they contribute to overall health and wellness.