American Society for Clinical Pathology (ASCP) Histotechnician Certification Practice Exam

Which statement accurately describes a vein?

1. It carries oxygen-rich blood

2. It contains structures called valves

3. It is located deeper than arteries

4. It is always larger than arteries

The correct answer is: It contains structures called valves

The statement that a vein contains structures called valves is correct because veins have one-way valves that prevent the backflow of blood, ensuring that it flows efficiently back to the heart. This is particularly important in the limbs, where blood must travel against gravity. The presence of valves helps maintain venous return, especially during physical activity or when a person is standing upright. In contrast, veins do not carry oxygen-rich blood, as arteries do; they usually transport deoxygenated blood back to the heart. While veins are generally located closer to the skin's surface than arteries, they also vary in size and can be smaller than certain arteries in specific locations. Therefore, stating that veins are always larger than arteries is not accurate, as their size can vary significantly based on the specific blood vessels in question.