THE IMMUNE SYSTEM
Definition of the Immune System The human immune system is a collective network of tissues, glands, and organs that work in a coordinated effort with each other to guard our bodies from foreign antigens such as viruses, bacteria, and infection causing microorganisms. For the immune system to work properly, two things must happen: first, the body must recognize that it has been invaded, either by pathogens or toxins or by some other threat. Second, the immune response must be activated quickly, before the invaders destroy many body tissue cells. For the immune system to respond effectively, several conditions must be in order, including the proper interaction of non-specific and specific defenses. The nonspecific
…show more content…
Macrophages act as effector cells in cell mediated immunity. Dendritic cells are mostly found in the skin and mucosal epithelium. Unlike macrophages, dendritic cells can also recognize viral particles that are unlike themselves. Lymphoid cells are the second type of cell in the immune system and these cells are responsible for immune responses. The lymphoid cells are composed of B lymphocytes (B-cells), T lymphocytes (T-cells), and natural killer cells. B-lymphocytes spend the earlier stages of life in the bone marrow. Their job is to travel through the blood and lymph searching for antigens which they can interlock with. Once a B-cell has found an antigen, it starts duplicating itself. These cloned cells mature into antibody creating plasma cells. T-lyphocytes travel through the blood and lymph looking for antigens. When an antigen is located, they notify other cells to help in combating the invader. Natural killer cells play a major role in the destruction of tumors and cells infected by viruses. They kill cells by releasing small amounts of proteins called perforin and granzyme that cause the target cell to die.
Types of Immune Responses We as humans are capable of two kinds of immune responses, innate and adaptive. Both the innate and immune responses distinguish between self and non-self antigens, but the degree of specificity underlying the recognition of the foreign entity, are very different. The innate response