Final answer:
During pregnancy, the uterus undergoes significant changes including a weight increase to around 2 pounds and a considerable expansion of the vascular system to support fetal requirements. The uterus does not develop a layer of mucus on the lung, and its capacity growth is more complex than just holding nearly a liter of fluid.
Step-by-step explanation:
The most significant changes in the uterus during pregnancy include a notable increase in weight and changes in the vascular system. Firstly, the weight of the uterus can increase to approximately 2 pounds by the end of pregnancy. This weight gain is part of the general increase in maternal weight, which also includes the growing fetus, amniotic fluid, and the placenta. Secondly, there is a substantial increase in the vascular system of the uterus, with the maternal blood volume increasing by about 30 percent, which can represent approximately 1-2 liters; this helps fulfill the needs of fetal nourishment and waste removal. It's important to note that while the uterus certainly increases in capacity during pregnancy, it does not specifically develop a layer of mucus on the lung as the uterus and lungs are separate organs, and the assertion that the uterus can hold nearly a liter of fluid is imprecise since the uterus expands considerably to accommodate the growing fetus.