Question

1. Which mechanisms are considered as the first line of defense and which ones are considered the second line of defense?
2. What are natural killer cells?
3. What is an inflammatory response? (What is it's purpose - why is it so important?)
4. How does the complement system work?

Answer 1

1. The body's first line of defense to fight against the infection which acts as a natural physical barrier includes skin, mucus, hairs of nose and ear, urine, raising body temperature, and vomiting. Human skin act as a natural protector against microbes as we clean the outer epidermis with soap and water thus it helps in removing the microbes from the surface. The mucous secreted by the mucous membrane is also helps to flush the germs from the body, Hairs of the nose also act as barriers to the entry pathogens via the respiratory tract. Similarly, increasing body temperature is also one cause to prevent infections on a primary basis. The urinary system passes urine which also removes several unwanted microbes from the body.

Innate immunity is known as the body's second line of defense system against foreign bodies. It is merely basis on antigen attached to the body and is trapped by cells to mask its effect. Several cells of the body play a role in it like phagocytes which has a mechanism to engulf the microbes and kill them. Inflammation is also another way in which swelling of that part happens where the attack happens. The RBC's causes swelling, redness at the site of action.