ANATOMY

Detailed explanation-1: -Mechanical barriers-which include the skin, mucous membranes, and fluids such as tears and urine-physically block pathogens from entering the body. Chemical barriers-such as enzymes in sweat, saliva, and semen-kill pathogens on body surfaces.

Detailed explanation-2: -Professional phagocytes play a central role in innate immunity by eliminating pathogenic bacteria, fungi and malignant cells, and contribute to adaptive immunity by presenting antigens to lymphocytes.

Detailed explanation-3: -Phagocytes (Innate Immunity) He identified two groups of phagocytic cells during his studies of bacterial infection and named these cells macrophages and microphages.