Final answer:
The upper respiratory tract is more commonly colonized by microbes compared to the lower respiratory tract due to its abundant and diverse microbiota. In contrast, the lower respiratory tract is considered to be essentially sterile.
Step-by-step explanation:
The upper respiratory tract is more commonly colonized by microbes compared to the lower respiratory tract. The upper respiratory tract is more commonly colonized by microbes compared to the lower respiratory tract due to its abundant and diverse microbiota. In contrast, the lower respiratory tract is considered to be essentially sterile.
This is because the upper respiratory tract contains an abundant and diverse microbiota, including species like Staphylococcus epidermidis, viridans group streptococci, and Haemophilus spp. In contrast, the lower respiratory tract has fewer microbial inhabitants and is considered to be essentially sterile.