AP BIOLOGY

Detailed explanation-1: -The macrophages and neutrophils of the innate immune system provide a first line of defense against many common microorganisms and are essential for the control of common bacterial infections.

Detailed explanation-2: -For example, cells of the innate immune system, such as neutrophils, macrophages and dendritic cells, serve as the body’s first line of defense against infection and other insults.

Detailed explanation-3: -Polymorphonuclear neutrophils (PMNs) are the most abundant leukocytes in the circulation, and the first cellular responders to tissue injury and infection.

Detailed explanation-4: -Macrophages are specialised cells involved in the detection, phagocytosis and destruction of bacteria and other harmful organisms. In addition, they can also present antigens to T cells and initiate inflammation by releasing molecules (known as cytokines) that activate other cells.

Detailed explanation-5: -Besides phagocytosis, macrophages play a central role in inflammation. They initiate the immune response against microorganisms, since macrophages are some of the first cells to come in contact with these invaders.