Skill:
• Annotation of diagrams of the nephron
The nephron is the functional unit of the kidney, with each nephron being comprised of the following components:
- Bowman’s capsule – first part of the nephron where blood is initially filtered (to form filtrate)
- Proximal convoluted tubule – folded structure connected to the Bowman’s capsule where selective reabsorption occurs
- Loop of Henle – a selectively permeable loop that descends into the medulla and establishes a salt gradient
- Distal convoluted tubule – a folded structure connected to the loop of Henle where further selective reabsorption occurs
The blood to be filtered enters the Bowman’s capsule via an afferent arteriole and leaves the capsule via an efferent arteriole
- Within the Bowman’s capsule, the blood is filtered at a capillary tuft called the glomerulus
- The efferent arteriole forms a blood network called the vasa recta that reabsorbs components of the filtrate from the nephron
Each nephron connects to a collecting duct (via the distal convoluted tubule), which feed into the renal pelvis
- The collecting ducts are shared by nephrons and hence are not technically considered to be part of a single nephron
Structure of a Nephron
⇒ Click on the image to show colour coding
Nephron Function
Nephrons filter blood and then reabsorb useful materials from the filtrate before eliminating the remainder as urine
This process occurs over three key stages:
- Ultrafiltration – Blood is filtered out of the glomerulus at the Bowman’s capsule to form filtrate
- Selective reabsorption – Usable materials are reabsorbed in convoluted tubules (both proximal and distal)
- Osmoregulation – The loop of Henle establishes a salt gradient, which draws water out of the collecting duct
Relationship between Nephron Structure and Function
