14.1.5—Nephron structure

A nephron is the functional unit of the kidney. Its continuous tubule is organised into a renal corpuscle—glomerulus within Bowman’s capsule—followed by the proximal convoluted tubule, loop of Henle, distal convoluted tubule and collecting duct.

Segment → high-level role:

• Glomerulus + Bowman’s capsule: the renal corpuscle receives blood and forms filtrate from small dissolved substances.
• Proximal convoluted tubule: the early tubule is the main site where useful solutes and some water are selectively recovered.
• Loop of Henle: the tubule extends between cortex and medulla, supporting later control of water and solute movement.
• Distal convoluted tubule: a later segment where the filtrate composition can be adjusted before collection.
• Collecting duct: receives fluid from nephrons and carries the final urine towards the renal pelvis; its water permeability is regulated in a later osmoregulation card.

The renal corpuscles, proximal and distal tubules are mainly associated with the cortex, while loops of Henle and collecting ducts extend through the medulla. Blood capillaries alongside the tubule allow substances recovered from filtrate to return to the blood. Different segment structures therefore support different stages of filtrate processing without making the nephron itself a single uniform tube.

Filtrate is not yet final urine at Bowman’s capsule: its composition changes as it passes along the nephron. This card maps segment structure and broad roles; the full ultrafiltration/reabsorption mechanism, osmoregulation and test-strip detection belong to later cards.