APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -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-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).