GENERAL HISTOLOGY

Detailed explanation-1: -Reviewed by Emily Henderson, B.Sc. The human body has three primary lines of defense to fight against foreign invaders, including viruses, bacteria, and fungi. The immune system’s three lines of defense include physical and chemical barriers, non-specific innate responses, and specific adaptive responses.

Detailed explanation-2: -Physical barriers include skin, mucus, digestive tract membranes, and traps of respiratory and urogenital which traps entering microorganisms.