what are the physical and chemical defenses of pathogens?

Question

like, how does the immune system defend itself against pathongens.

Answer 1

Barriers
Things like skin and tissues which prevent pathogens from getting access to internal tissues.


Humoral system (chemical)
i.e. Antibodies, the Compliment systems, Clotting systems (Intrinsic and extrinsic clotting pathways) (which can trap certain foreign material).


Cellular system
-Neutrophils (ordinary white cells which are phagocytes - they eat pathogens).
-Macrophages and Monocytes (similar to Neutrophils, but are in league with humoral system to help recognize new threats and concoct new antibodies)
-Lymphocytes
--B Cells (actually part of the humoral system - they produce antibodies)
--T Cells - They fight some of the heartier pathogens - viruses, TB, fungi, cancer cells.
---T Cells come in several forms helper and suppressor cells. The helper (T4) cells are targeted by HIV, which is why it compromises the immune system.

Lymphatic system
The lymphatic system has three interrelated functions: (1) removal of excess fluids from body tissues, (2) absorption of fatty acids and subsequent transport of fat, chyle, to the circulatory system and, (3) production of immune cells (such as lymphocytes, monocytes, and antibody producing cells called plasma cells).