For a body surface to be a respiratory surface, it must __________.

• A. be dry and covered with hair
• B. be moist and glandular
• C. be thick and moist
• D. be internal
• E. be thin and moist

Answer: (E)

Verified step by step guidance

1. Understand the function of a respiratory surface: It is a site where gas exchange occurs, allowing oxygen to enter the body and carbon dioxide to exit.
2. Recognize the importance of moisture: A moist surface is crucial because gases dissolve in water, facilitating their diffusion across the respiratory surface.
3. Consider the thickness of the surface: A thin surface is essential for efficient gas exchange, as it reduces the distance over which gases must diffuse.
4. Evaluate the options given: Compare each option to the requirements for effective gas exchange, focusing on moisture and thickness.
5. Conclude that the correct characteristics for a respiratory surface are that it must be thin and moist, as these conditions optimize the diffusion of gases.