Lesson 2 ·Class 10 · The Excretory System · Label Lab
Kidney and Nephron Structure
Label the tubule that makes urine.
Tap any part of the diagram to learn its name and its job. Try: Trace the filtrate in order: Bowman's capsule, proximal tubule, loop of Henle, distal tubule, collecting duct.
Free play — explore the diagram, or switch to "Label it yourself" and place every label. Switch to when you're ready to test yourself.
The Bowman's capsule and both convoluted tubules sit in the cortex, which is why the cortex looks dotted. The loops of Henle and the collecting ducts sit in the medulla, which is why the medulla looks striped.
What this lesson covers
What you do
- Trace the filtrate in order: Bowman's capsule, proximal tubule, loop of Henle, distal tubule, collecting duct.
- About two million of these tubules work in the two kidneys, over 60 km of tubing in all, giving a huge surface for reabsorption.
The parts you label
- Bowman's capsule — A thin-walled cup, only one cell thick, like a hollow ball pressed in on one side. Its inner space leads straight into the tubule.
- Glomerulus — A knot-like mass of blood capillaries fitting closely inside the cup. Together with the Bowman's capsule it forms the Malpighian or renal capsule.
- Proximal convoluted tubule — The first coiled region, nearest the capsule. It reabsorbs about two-thirds of the water along with much of the glucose, sodium and chloride.
- Loop of Henle — The hair-pin shaped middle part. It is not convoluted; it runs down into the medulla, turns back and re-enters the cortex, absorbing some water and sodium ions.
- Distal convoluted tubule — The far coiled end of the tubule, back in the cortex. Its walls secrete potassium and foreign chemicals such as penicillin into the forming urine.
- Collecting duct — Receives the contents of many kidney tubules and pours them as urine into the pelvis of the kidney.
- Afferent arteriole — Brings blood into the glomerulus. It is the wider of the two vessels, which is what keeps the pressure inside high enough to filter.
- Efferent arteriole — Carries blood away from the glomerulus. Being narrower than the one coming in, it holds the pressure up rather than letting it drop.
- Peritubular capillaries — The net of capillaries wrapped round the tubule. Whatever the tubule reabsorbs is handed straight back to the blood here.
Challenges to clear
- Find the only part shaped like a hair-pin.
- Find the tubule where potassium and drugs are secreted into the urine.
- Place every label on the nephron.
- Tap the vessel that brings blood into the glomerulus.
- Tap the capillary net that takes back whatever the tubule reabsorbs.
Hint
The Bowman's capsule and both convoluted tubules sit in the cortex, which is why the cortex looks dotted. The loops of Henle and the collecting ducts sit in the medulla, which is why the medulla looks striped.