The glomerulus is primarily responsible for which function in urine formation?

• A. Reabsorption of substances from filtrate
• B. Secretion of hormones into urine
• C. Filtration of blood to form urine
• D. Storage of urine in the bladder

Answer: (C)

The glomerulus is where blood filtration begins in urine formation. Within the renal corpuscle, the glomerular filtration barrier allows water and small solutes to move from blood into Bowman's capsule, forming the filtrate that will be processed along the nephron. Large molecules and cells remain in the bloodstream, so this step is responsible for creating the initial filtrate, not for reabsorbing substances, secreting into urine, or storing urine. Reabsorption and secretion occur later along the tubules, while storage happens in the bladder.