IMMUNOLOGY

Detailed explanation-1: -Sweat, mucus, tears, and saliva all contain enzymes that kill pathogens. Urine i s too acid ic for many pathogens, and semen contains zinc, which most pathogens cannot tolerate. In addition, stomach acid kills pathogens that enter the GI tract in food or water.

Detailed explanation-2: -Stomach acid is a chemical barrier against infection. It is hydrochloric acid and is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water.

Detailed explanation-3: -Chemical barriers against infection include enzymes in tears, saliva and mucus that break down the surface of bacteria. The acid in sweat and in the stomach kills cellular pathogens and there are anti-bacterial proteins in semen (the fluid that contains male sperm).

Detailed explanation-4: -The mucus secreted by gastrointestinal tract together with various other substances forms the intestinal mucosal chemical barrier, which is the key component of the body’s natural immune system. Among all these substances, mucus is the most effective one in protecting the surface of intestinal mucosa.

Detailed explanation-5: -First, the stomach wall is covered by a thick coating of bicarbonate-rich mucus. This mucus forms a physical barrier, and its bicarbonate ions neutralize acid. Second, the epithelial cells of the stomach’s mucosa meet at tight junctions, which block gastric juice from penetrating the underlying tissue layers.

Detailed explanation-6: -Chemical barriers in human include tears, breast milk, sweat, saliva, stomach acid.

Detailed explanation-7: -Chemical barriers of innate immunity: Chemical barriers block entry of pathogens at body openings and inner body surfaces. Examples of chemical barriers include sweat, breastmilk, mucus, saliva, tears and semen. Vaginal secretion is acidic in nature and is not endured by pathogens.