Final answer:
The nephron is the functional unit of the kidney, and it is responsible for filtering and purifying the blood to produce urine. It includes a renal corpuscle, a renal tubule, and associated capillary networks. Nephrons perform glomerular filtration, tubular reabsorption, and tubular secretion. The correct option is 4) nephron
Step-by-step explanation:
The functional unit of the kidney is the nephron. Each kidney contains over one million nephrons, which are responsible for filtering the blood, removing waste, and balancing bodily fluids to produce urine. A nephron is comprised of several parts including a renal corpuscle, a renal tubule (which contains a proximal convoluted tubule, loop of Henle, distal convoluted tubule), and collecting ducts.
Nephrons are categorized into two types: cortical nephrons and juxtamedullary nephrons. Cortical nephrons are located deep in the renal cortex and makeup 85 percent of all nephrons, while juxtamedullary nephrons, which constitute the remaining 15 percent, are located near the renal medulla.
The process of urine formation involves three vital functions: glomerular filtration at the renal corpuscle, tubular reabsorption, and tubular secretion along the renal tubule. Ultimately, urine flows from the nephrons to the renal papilla and into the ureter. The correct option is 4) nephron