List the 3 lines defence of body?

The three lines of defense in the body are:

1. Physical barriers

- Skin: The skin acts as a barrier against microorganisms, chemicals, and other environmental hazards.

- Mucous membranes: Mucous membranes line the respiratory, digestive, and urogenital tracts and produce mucus that traps microorganisms and debris.

- Tears, saliva, and gastric juices: These fluids contain chemicals that can kill or inhibit the growth of microorganisms.

2. Innate immune responses

- Phagocytes: These cells engulf and destroy microorganisms and other foreign particles.

- Natural killer cells: These cells attack and kill cells that are infected with viruses or are otherwise abnormal.

- Inflammation: Inflammation is a response to tissue damage that results in increased blood flow, swelling, heat, and pain. Inflammation helps to recruit immune cells to the site of injury and to clear away damaged tissue.

3. Adaptive immune responses

- Antibodies: Antibodies are proteins that are produced by B cells and that recognize specific antigens. Antibodies can neutralize microorganisms, prevent them from entering cells, and target them for destruction by phagocytes.

- T cells: T cells are a type of white blood cell that recognize specific antigens and help to coordinate the adaptive immune response.

- Cell-mediated immunity: Cell-mediated immunity involves the killing of infected cells by T cells and natural killer cells.

- Memory cells: Memory cells are a type of B cell and T cell that can persist for long periods of time and provide immunity to future infections with the same pathogen.