Question

Animal Physiology Questions

1. Why do most multicellular organisms require more than just diffusion to facilitate gas exchange? What is the other process called? Name all the places in our body where these two different processes occur (i.e. where do we get diffusion and where do we get the other process).
2. Explain the sigmoidal shape of the oxygen equilibrium curve for vertebrate hemoglobin. Why does the myoglobin oxygen equilibrium curve look different? If you were to draw these curves graphically, what would be on the x-axis? What would be on the y-axis?

Answer 1

Direct transfer of gas is not possible for most multicellular organisms. Multicellular organisms require a system for gas exchange between the environment and another for the gas transport to each and every cell by increasing pressure differences, increasing area and decreasing distance.

Multicellular organisms possess respiratory organs that increase the surface area available for diffusion located in the gills, tracheae, and lungs. These adaptations bring the external environment close to the internal fluid such as blood or hemolymph, which is circulated throughout the body.