Which of the following describes how diffusion works in the maternal-fetal exchange?

The concept of diffusion is pivotal in understanding how substances are exchanged between the mother and fetus. In the context of maternal-fetal exchange, diffusion refers to the movement of substances from areas of higher concentration to areas of lower concentration.

When considering nutrients, they typically transfer from the mother to the fetus where they are in lower concentration. This movement is crucial for fetal growth and development. Hence, the correct mechanism described is the movement of nutrients from an area of high concentration in the maternal bloodstream to a lower concentration in the fetal circulation.

For oxygen, it follows a similar pattern; oxygen diffuses from the maternal blood, where levels are relatively high due to the mother’s respiration, into the fetal blood, where oxygen levels are lower. This transfer is essential for fetal metabolism, as oxygen is critical for energy production.

The exchange of carbon dioxide also takes place through diffusion, but in reverse. The fetus produces CO2 as a metabolic waste product, which then diffuses back to the mother, where the concentration of CO2 is lower, allowing for its expulsion through the mother's respiratory system.

All these processes together exemplify the seamless nature of diffusion, highlighting that substances move in the direction of their concentration gradients—thus supporting the need for all statements regarding nutrients,