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Difficulty: HardHuman Anatomy and Body Systems

The human urinary system relies on specialized anatomical regions within the nephron to filter metabolic waste, reclaim essential solutes, and concentrate urine. Match each nephron segment on the left with its primary physiological function on the right.

  • Glomerulus and Bowman's capsuleNon-selective ultrafiltration of blood plasma driven by hydrostatic pressure
  • Proximal convoluted tubuleObligatory bulk reabsorption of filtered glucose, amino acids, and bicarbonate
  • Thick ascending limb of the loop of HenleActive solute reabsorption without water permeability to create a medullary osmotic gradient
  • Distal convoluted tubule and collecting ductHormonally regulated facultative reabsorption of water and sodium via ADH and aldosterone

Answer

Glomerulus and Bowman's capsule matches non-selective ultrafiltration driven by hydrostatic pressure; Proximal convoluted tubule matches obligatory bulk reabsorption of glucose, amino acids, and bicarbonate; Thick ascending limb matches active solute reabsorption without water permeability to establish a medullary gradient; Distal convoluted tubule and collecting duct matches hormonally regulated facultative reabsorption via ADH and aldosterone.
Each nephron segment possesses distinct histological features suited to its physiological function: the glomerulus and Bowman's capsule perform bulk filtration through physical pressure gradients; the proximal tubule performs non-regulated bulk nutrient and ion reclamation; the ascending limb drives active ion transport without water movement to create the hyperosmotic medullary gradient; and the distal segments provide variable, hormone-gated homeostatic regulation.

Step-by-Step Solution

1
Identify the primary site of initial plasma filtration in the nephron.
The renal corpuscle (glomerulus surrounded by Bowman's capsule) filters blood plasma under high hydrostatic pressure, retaining cellular elements and large proteins.
Filtration is passive and driven by Starling forces across the fenestrated capillary endothelium and podocyte filtration slits.
2
Determine where the majority of filtered nutrients and electrolytes are reclaimed.
The proximal convoluted tubule possesses a dense microvillar brush border specialized for active and secondary active transport, reclaiming virtually all glucose, amino acids, and the majority of electrolytes.
This is obligatory reabsorption, operating independently of systemic hydration hormones.
3
Identify the segment responsible for establishing the countercurrent multiplier mechanism.
The thick ascending limb of the loop of Henle actively transports sodium, potassium, and chloride ions out of the filtrate while remaining impermeable to water molecules.
This dilutes the luminal fluid while creating a high solute concentration in the renal medullary interstitium.
4
Identify the target structures for endocrine regulation of water and electrolyte balance.
The distal convoluted tubule and collecting duct adjust final urine concentration in response to circulating hormones such as aldosterone and antidiuretic hormone (vasopressin).
Aquaporin channel insertion and sodium-potassium ATPase activity in these late segments are variable and tightly regulated to preserve homeostasis.

Key Concept

Nephron functional compartmentalization and renal transport physiology
Estimated Time:1m 30s
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Topics

Human Anatomy and Body Systems

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