• Digestive System
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    Introduction to the Digestive System The digestive system is completed by the gastrointestinal tract—also known as the GI tract or digestive tract. The GI tract is a sequence of hollow organs connected in a long, twisting tube from the mouth to the anus. The hollow organs that build up the GI tract include mouth, oesophagus, ...
  • Immune System
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    Introduction to Immune System The immune system is a host protection system encompassing many biological structures and procedures within an organism that defends the body against disease. To function appropriately, an immune system must notice a wide variety of agents, termed as pathogens, from viruses to parasitic worms, and differentiate them from the organism’s own ...