ANATOMY

Detailed explanation-1: -Skin is a barrier that serves as one of the body’s first lines of defense against harmful microbes. Specialized immune cells within skin tissue help to fight invading organisms.

Detailed explanation-2: -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-3: -The skin is part of the first line of defense protecting the body from infection. It harbors a range of immune cells, including Langerhans cells (Langerhans, 1868). Initially thought to be part of the nervous system, Langerhans cells play an important role in the defense against pathogens (Schuler and Steinman, 1985).

Detailed explanation-4: -The first line of defense against infection are the surface barriers that prevent the entry of pathogens into the body. The second line of defense are the non-specific phagocytes and other internal mechanisms that comprise innate immunity.

Detailed explanation-5: -Answer and Explanation: The production of sebum by sebaceous glands in epithelial membranes would be considered a first line of defense against pathogen infection. Sebum provides a physical barrier against infection, and it also exhibits antibacterial activity (due to the presence of certain fatty acids).