Which of the following are considered the main portals of entry for pathogens into the human body?

• A. Bones, muscles, nerves, and joints
• B. Liver, pancreas, spleen, and heart
• C. Blood vessels, lymph nodes, cartilage, and tendons
• D. Skin, respiratory tract, gastrointestinal tract, and urogenital tract

Answer: (D)

Verified step by step guidance

1. Understand that portals of entry are the routes through which pathogens enter the human body to cause infection.
2. Recall the common and main portals of entry, which include external surfaces or openings that pathogens can access easily.
3. Identify that bones, muscles, nerves, joints, liver, pancreas, spleen, heart, blood vessels, lymph nodes, cartilage, and tendons are internal structures and not typical entry points for pathogens.
4. Recognize that the skin, respiratory tract, gastrointestinal tract, and urogenital tract are the primary external interfaces with the environment and serve as the main portals of entry.
5. Conclude that the correct answer lists the main portals of entry as skin, respiratory tract, gastrointestinal tract, and urogenital tract.