In the urinary system, what are the basic functional units of the kidney responsible for filtering blood and forming urine?

• A. Alveoli
• B. Villi
• C. Nephrons
• D. Haversian systems (osteons)

Answer: (C)

Verified step by step guidance

1. Identify the main structures listed in the problem and their functions: Alveoli are involved in gas exchange in the lungs; Villi are finger-like projections in the small intestine that aid nutrient absorption; Haversian systems (osteons) are structural units in compact bone.
2. Recall that the kidney's primary role is to filter blood and form urine, which requires specialized microscopic structures.
3. Understand that the nephron is the microscopic functional unit of the kidney responsible for filtering blood, removing waste, and forming urine.
4. Recognize that each kidney contains about a million nephrons, each consisting of a glomerulus and a renal tubule where filtration and reabsorption occur.
5. Conclude that among the options given, nephrons are the correct answer as they perform the essential functions of blood filtration and urine formation in the urinary system.