Final answer:
Barriers to pathogens and toxins presented by the physical characteristics of the GI tract are best described as physical barriers. These include the skin, mucosal surfaces, mucus, cilia, and stomach acid that prevent pathogens from entering the body.
Step-by-step explanation:
Barriers to pathogens and toxins presented by the physical characteristics of the gastrointestinal (GI) tract are best described as examples of physical barriers.
Physical barriers include the skin, mucosal surfaces, mucus, cilia, and stomach acid that prevent pathogens from entering the body.
For example, the skin acts as a physical barrier by preventing pathogens from entering the body through abrasions or punctures.
The mucus and cilia in the respiratory tract trap and remove pathogens.
Overall, physical barriers play a crucial role in protecting the body from pathogens and toxins