CNRN Practice Exam 2026 – Complete Prep for Your Certification Test

The duodenum is the first part of the small intestine, and its length typically measures approximately 25 to 30 centimeters in adults, which aligns with the choice indicating a length of 28 cm. This section plays a crucial role in digestion as it receives chyme from the stomach, along with bile from the liver and pancreatic juices, facilitating the digestion of nutrients. By recognizing the function and anatomical location of the duodenum, noting that it is about one foot long in terms of functional length, the choice of 28 cm becomes clear as the most accurate representation of its average length in the human body.