ANATOMY

Detailed explanation-1: -The innate immune system includes physical and anatomical barriers as well as effector cells, antimicrobial peptides, soluble mediators, and cell receptors (Table 1). Skin and mucosa provide an effective immune barrier between the internal and external environment.

Detailed explanation-2: -The first line of defence is non-specific and aims to stop microbes from entering the body. The skin and mucous membranes act as a physical barrier preventing penetration by microbes. If the skin is cut then the blood produces a clot which seals the wound and prevents microbes from entering.

Detailed explanation-3: -The mucous membranes lining the nose, mouth, lungs, and urinary and digestive tracts provide another nonspecific barrier against potential pathogens. Mucous membranes consist of a layer of epithelial cells bound by tight junctions.

Detailed explanation-4: -The innate immune system activates special immune system cells and proteins if germs get past the skin and mucous membranes and enter the body.

Detailed explanation-5: -Answer and Explanation: The right option is d) sweat. Our skin is the body’s first line of defenses against bacteria and other harmful organisms. Sebaceous glands in the skin produce sweat and sebum to protect the skin.