ANATOMY

Detailed explanation-1: -The first line of defence (or outside defence system) includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, ‘friendly’ bacteria and white blood cells called neutrophils.

Detailed explanation-2: -“White blood cells are among other places located in the oral mucosa, and they represent the body’s first line of defence against infectious agents. The mucus in the mouth causes the white blood cells to throw out a ‘net’ that traps bacteria”, explains Ole Sørensen from the Division of Infection Medicine.

Detailed explanation-3: -The first line of defence is your innate immune system. Level one of this system consists of physical barriers like your skin and the mucosal lining in your respiratory tract. The tears, sweat, saliva and mucous produced by the skin and mucosal lining are part of that physical barrier, too.

Detailed explanation-4: -Along with the intestinal epithelium, the microbiota forms a protective barrier against infectious threats and plays an active role in promoting and maintaining the immune homeostasis during intestinal infections.

Detailed explanation-5: -Keratinocytes. Keratinocytes are the predominant cells in the epidermis. They act as the first line of innate immune defence against infection.