ANATOMY

Detailed explanation-1: -Answer and Explanation: Fever is not the first line of defense; it is considered the second line of defense. Suppose the first line of defense couldn’t protect the body, and the pathogen still enters the body. In that case, the second line of defense protects the body, including fever, inflammation, and phagocytosis.

Detailed explanation-2: -Innate immune cells are the body’s first line of defense. They quickly respond to foreign cells to fight infection, battle a virus or defend the body against bacteria. T-cells and B-cells react when invading organisms slip through that first line using a process called acquired immunity (or adaptive immunity).

Detailed explanation-3: -Physical barrier The innate immune system provides the first line of defense, which is divided broadly into two categories – physical/chemical barriers and nonspecific resistance.

Detailed explanation-4: -Skin, tears and mucus are part of the first line of defence in fighting infection. They help to protect us against invading pathogens.