Biological Systems MCAT Practice Exam

What physiological change occurs during pregnancy that increases the need for certain resources in the body?

1. Increased demand for carbohydrate metabolism

2. Increased demand for oxygen and nutrients

3. Decreased blood volume

4. Increased fertility rates

The correct answer is: Increased demand for oxygen and nutrients

During pregnancy, a woman's body undergoes significant physiological adaptations to support the developing fetus. One of the most critical changes is the increased demand for oxygen and nutrients. As the fetus grows, it requires a steady supply of oxygen and essential nutrients to develop properly. To meet this increased demand, the mother's cardiovascular system adapts in several ways. For instance, there is an increase in blood volume, which enhances the capacity to transport oxygen and nutrients. This increased blood volume leads to an increased cardiac output, allowing for more efficient circulation to both the mother and the fetus. Additionally, the placenta plays a vital role in nutrient and gas exchange. It acts as an interface between maternal blood and fetal blood, and it needs to be well supplied with oxygen and nutrients to function effectively. The mother's body also experiences hormonal changes that contribute to these physiological adaptations, promoting a higher metabolic rate and greater oxygen consumption. In summary, the increased demand for oxygen and nutrients during pregnancy is a fundamental change that ensures the health and development of the fetus, highlighting the importance of these resources for both maternal and fetal well-being.