Nephron
From these slides, focus on these 5 points.
KIDNEYS and URETERS(1).pdf
Topic | What you should know |
Nephron | Microscopic structural and functional unit of the kidney; approximately 1–1.5 million per kidney in your slides |
Renal corpuscle | Glomerulus + Bowman’s capsule; site of blood filtration |
Renal tubule | Proximal tubule → loop of Henle → distal tubule → connecting tubule, then drains into collecting ducts |
Tubular processing | Reabsorption returns water and substances to blood; secretion transfers substances into tubular fluid |
Final urine | Fluid remaining after filtration and tubular processing |
Filtration barrier — memorize the three layers in order:
Capillary endothelium → glomerular basement membrane → filtration slits between podocyte foot processes
Juxtaglomerular apparatus — the most important comparison:
Feature | Juxtaglomerular cells | Macula densa |
Location | Wall of the afferent arteriole | Specialized cells in the distal tubular region next to the glomerulus |
Cell type | Modified smooth muscle cells | Specialized tubular epithelial cells |
Main function | Secrete renin | Sense tubular NaCl delivery |
Renin → ↑ angiotensin II → ↑ aldosterone → sodium and water retention → supports blood pressure.
Exam traps:
Glomerulus ≠ renal corpuscle: the corpuscle includes Bowman’s capsule.
Juxtaglomerular cells secrete renin; macula densa senses NaCl.
Collecting ducts receive fluid from multiple nephrons and are generally considered separate from the nephron itself.