Step 1: Understanding the Concept:
A functional unit is the smallest part of an organ that can perform all the functions of that organ. For the kidney, this means filtering blood and forming urine.
Step 2: Detailed Explanation:
Each human kidney contains approximately 1 million nephrons.
• Neuron: The functional unit of the nervous system.
• Nephron: The microscopic structure that filters blood, reabsorbs what is needed, and excretes the rest as urine.
• Glomerulus/Bowman capsule: These are actually parts of the nephron, not the entire functional unit itself.
Step 3: Final Answer:
The functional unit of the kidney is the nephron.