Question

in terms of innate immunity what is the body's second line of defense against microbial infection/disease? explain the roles of the formed elements in the blood, lymphatic system, and phagocytes.

Answer 1

The second line of defence is a group of cells, tissues and organs that work together to protect the body. This is the immune Sustem This response is rapid, short-lived and generic, and it lacks any memory of previous infections Important components of this innate immunity include: I. Phagocytes Cells that engulf microorganisms or cells that are infected, damaged or dying. These phagocytic cells are macrophages and neutrophils. They enclose the antiqens in a vesicle called a phagosome and are breaken down with hydrolytic enzymes. The remains are presented to other specialised immune cells that initiate a more targeted immune response

2. Natural killer cells These cells kill everything they meet with the help of recognition of self markers - major histocompatibility complex (MHC) proteins on the surface of the cells they make contact with. NK cells release chemicals calledd cytokines, which alert and attract other immune cells, 3. Complement tere blood also play an important role in innate immunity because there are around 30 proteins in the blood plasma that can be activated bu the presence of microbes or antibody-antigern complexes. Complement can destroy pathogens and activate phagocytic cells

4. Inflammation When the receptors of cells involved in the non-specific immune system are engaged by pathogens, the cells release molecules that trigger inflammation. Increased blood leads to swelling indicating that something is wrong. Higher blood flow causes an increase in temperature, which can inhibit the replication of some bacteria anc Viruses.