NANP Board Practice Exam

Which term is used to describe glutamine's role in inter-organ amino acid exchange?

1. Nitrogen shuttle

2. Oxygen carrier

3. Protein transporter

4. Stress hormone

The correct answer is: Nitrogen shuttle

Glutamine is often described in the context of inter-organ amino acid exchange as a nitrogen shuttle. This term highlights its primary function in facilitating the transfer of nitrogen between different tissues in the body. Glutamine is the most abundant amino acid in the blood and serves as a key nitrogen source for various anabolic processes in organs, particularly during times of stress or when the body is in a state of high demand for amino acids. During this transfer, glutamine can be released from skeletal muscle into the bloodstream and taken up by organs such as the intestines, liver, and kidneys, where it can be converted into other essential molecules. This process is crucial for maintaining a balanced amino acid pool in the body and supports various metabolic functions. The other terms do not accurately describe glutamine's specific role: an oxygen carrier typically refers to hemoglobin or other molecules that transport oxygen; a protein transporter implies a broader category of molecules that move proteins or peptides across membranes; and a stress hormone usually pertains to hormones like cortisol, which respond to stress rather than amino acids involved in nitrogen metabolism.