Answer: See Below
Step-by-step explanation:
Macrophages are specialized cells of the innate immune system that play a crucial role in phagocytosis of bacteria. When bacteria invade our body, they are recognized by the macrophages through pattern recognition receptors (PRRs) on their cell surface. The PRRs can recognize specific patterns or structures present on the surface of the bacteria called pathogen-associated molecular patterns (PAMPs).
Once the macrophages recognize the presence of bacteria, they engulf them through a process called phagocytosis. During this process, the macrophages extend their pseudopods around the bacteria and form a phagosome, which is a membrane-bound compartment that encloses the bacteria. The phagosome then fuses with lysosomes, which contain enzymes and other molecules that can kill and degrade the bacteria.
Macrophages also have the ability to present bacterial antigens to other cells of the immune system, such as T cells. This process is known as antigen presentation, and it allows T cells to recognize and respond to the bacteria more efficiently. The antigen-presenting cells (APCs) such as macrophages, present the bacterial antigens to T cells in the context of major histocompatibility complex (MHC) molecules on their surface. This interaction activates the T cells, which can then differentiate into effector cells that can directly kill the bacteria or produce cytokines that further activate the immune response.
In summary, the innate immune system uses macrophages and phagocytosis as a first-line defense mechanism against bacterial infections. The macrophages can recognize and engulf bacteria through PRRs, and subsequently kill and degrade them through lysosomal enzymes. They can also present bacterial antigens to T cells, which activates the adaptive immune system to mount a more specific and effective response.