Final answer:
The placenta, with its rich network of blood vessels and chorionic villi, enables efficient gas and nutrient exchange between mother and fetus while protecting the fetus from the mother's immune system. Oxygen, carbon dioxide, and nutrients like glucose, amino acids, and iron are transferred via diffusion and active transport mechanisms. Oxygen uptake is facilitated by fetal hemoglobin's higher affinity for oxygen compared to maternal hemoglobin.
Step-by-step explanation:
The placenta is an essential organ in placental mammals, including humans, that allows efficient gas exchange between the mother and the fetus. Nutrients and wastes are exchanged through the umbilical cord, connecting the fetus to the placenta. The placenta consists of maternal and embryonic blood vessels separated by membranes, ensuring that fetal and maternal blood does not mix, which protects the fetus from the mother's immune system.
For gas exchange, the placenta utilizes a high surface area provided by chorionic villi, where oxygen and carbon dioxide are exchanged by simple diffusion, with fetal hemoglobin having a greater affinity for oxygen than maternal hemoglobin to enhance oxygen uptake. Nutrients such as glucose pass via facilitated diffusion, while amino acids and iron utilize active transport to meet the high demand of the fetus. Wastes are efficiently removed from fetal blood through capillaries in the chorionic villi and returned to the maternal circulation for disposal.
The placenta fully develops by weeks 14-16 and continues to serve as the site of nutrition, respiration, and waste management for the growing fetus throughout the pregnancy. This intricate system of exchange is crucial for the survival and development of the fetus before birth.