Asked Nov 11, 2019

Can I get clarification on the three lines of defense and the cells that take place in each group? (ex. b cells and t cells, cell-mediated and humoral immunities...etc)


Expert Answer

Step 1

The immune system of a human body is the responsible for defending the individual from any harmful agent. The lymphatic system is part of immune system which is composed of lymphatic organs, lymphatic nodes and lymphatic vessels.

Step 2

Immune system is primarily divided into two types, the innate immunity and the adaptive immunity. On one hand when innate immune system acts in a non-specific manner, adaptive immune system on the other hand, acts in antigen specific manner and has memory of each encounter.

Innate immune system comprises two line of defenses.

The first line of defense is the chemical and physical barrier that includes lining the openings of body with layers of cilia, hair, mucus, skin or expelling out the microorganisms using mechanisms like vomiting, defecation or urine. Chemical barriers of body include lining the inner or outer layer of an organ with different chemical components. The components of chemical barriers include hyaluronic acid, sebum, acidity, saliva, gastric juices and lysozyme.

The second line of defense include destroying the pathogens in a non-specific manner that include phagocytic cells, inflammation and fever. The phagocytic cells include ingesting and destroying the microbes. The mechanism of inflammation works by bringing white blood cells at the sit...

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