Medical Assistant Certification (MAC) AMCA Practice Exam

What is the functional unit of the kidney?

1. Glomerulus

2. Nephron

3. Renal pelvis

4. Ureter

The correct answer is: Nephron

The nephron is recognized as the functional unit of the kidney because it is the primary structure responsible for the processes of filtration, reabsorption, and secretion, which are crucial for the formation of urine. Each kidney contains approximately one million nephrons that work together to maintain the body's fluid and electrolyte balance, eliminate waste, and regulate blood pressure. The nephron includes several key components: the glomerulus, which filters blood, and the renal tubules, where reabsorption and secretion occur. This intricate system ensures that essential substances are retained in the body while waste products are removed efficiently. In contrast, while the glomerulus is an important part of the nephron that initiates the filtration process, it does not encompass the full range of functions associated with the nephron. The renal pelvis serves as a funnel for urine collected from the nephrons but does not perform the filtration or reabsorption functions. The ureter's primary function is to transport urine from the kidneys to the bladder, rather than processing and filtering blood. Thus, the nephron's comprehensive role in renal function solidifies its status as the functional unit of the kidney.