Name and briefly describe the two branches of immune systems ?

Answer: 1. the innate immune system and 2. the adaptive immune system

1. The innate immune system - is one of the main branches of the immune system and is composed barriers and activates immediately once a pathogen attack occurs. It's purpose is to prevent and limit the spread of pathogens or other foreign particles.

It is composed in turn of:

a. physical barriers - ex. skin, respiratory tract, eyelashes etc

b. general immune responses - complement (which marks and destroys pathogens) and the inflammatory response (which brings the immune cells to the site of the infection through increased blood flow)

c. defense mechanisms - ex. secretions, gastric acid, saliva, tears, sweat etc.

This branch is general and nonspecific as it attacks everything foreign. It is activated by antigens.

2. The adaptive immune system -  is composed of two types of lymphocytes:

a. B cells - produced by the bone marrow, they become specialized for specific pathogens through different antigens. The cell will divide into memory cells (will express the parent cell's antibody) and plasma cells (which will secrete antibodies)

b. T cells - produced by the thymus perform multiple functions such as:

                          - attack foreign substances

                          - augment the response of B cells

                          - direct responses and activities in other immune cells

                            through substances known as cytokines

This branch of the immune system is pathogen specific and it requires the recognition of specific "non-self" antigens.