Acquired immune system

The acquired immune response is specific and has memory. • Specificity – ability to recognize, and respond to specific targets • Memory – second exposure to the same antigen produces a larger and more rapid response. The adaptive immune response is much slower than the innate immune response.

Effector cells - type of cell in the body that carries out a specific activity in response to stimulation. Each lymphocyte has specific receptors for only one antigen.

Antigens are molecules which are recognised by receptors on lymphocytes and elicit a specific immune response to that antigen Antigen presenting cells (APCs) collect antigens from infected tissues and display them to activate lymphoid cells.

act as messengers between cells of the immune system

B Lymphocytes (B Cells) B cells are derived from stem cells in the bone marrow travel to lymphatic tissues especially the spleen and lymph nodes

T Lymphocytes (T cells) T cells like B cells are derived from stem cells in the bone marrow T cells travel and mature in the thymus

Organs of immune system are throughout the body called lymphoid organs because they contain lymphocytes - the wbc. Within these lymphoid organs lymphocytes grow, develop and are deployed.

Lymphoid organ: Bone marrow (the soft tissue in the hollow center of bones) is the original source of all blood cells, including the immune cells.

Lymphoid organ: The spleen is a flattened organ at the upper left of the abdomen. Like the lymph nodes, the spleen contains specialized compartments where immune cells gather and confront antigens

Lymphoid organ: The thymus is an organ that lies behind the breastbone; lymphocytes known as T lymphocytes, or just T cells, mature there.

Clumps of lymphoid tissue are found in many parts of the body linings of the digestive tract the airways and lungs (gateways to the body). These tissues include the tonsils, adenoids, and appendix