The functional unit of the kidney is called the nephron. Each kidney contains approximately one million nephrons, which are responsible for filtering blood, reabsorbing essential nutrients, and excreting waste products in the form of urine. The nephron comprises several key structures, including the renal corpuscle, which contains the glomerulus and Bowman’s capsule, as well as the renal tubules, where further processing of filtrate occurs.
The role of the nephron is crucial for maintaining homeostasis by regulating fluid balance, electrolyte levels, and acid-base balance. It does this through processes like filtration, secretion, and reabsorption. Understanding the nephron's anatomy and physiology is essential for comprehending how the kidney functions overall.
While the glomerulus is an important part of the nephron involved in the filtration process, it is just one component and does not represent the entire functional unit. The collecting duct assists in water reabsorption and plays a role in urine concentration but is also part of the nephron rather than the functional unit itself. An alveolus, typically associated with the lungs, is not relevant to kidney function.