Year 11 Pupils Investigate the Kidney

As part of their GCSE Biology course, Year 11 pupils today investigated the structure of the kidney.

The Dissection Begins

The kidneys are two bean-shaped organs attached to the rear wall of the abdominal cavity. They have a rich blood supply, and as the blood passes through them it is filtered by millions of little structures called nephrons, consisting of: a glomerulus (a coiled ball of capillary blood vessels), and a kidney tubule (of which there are over 1 million, or 60 km worth per kidney).

A Nephron

Finishing Touches

Blood flows into each glomerulus from the renal artery. Small molecules ‘leak out’ under pressure filtration, into the Bowman’s capsule of the tubule. The small molecules are: water, urea, sugar and salt. The urea and most of the water flow down the tubule to a collecting duct and ultimately into the ureter and bladder to be excreted as urine. Useful materials however, like glucose and salt, are actively transported back into the capillaries surrounding each tubule – a process known as selective reabsorption.  

In cross-section, a kidney has two main regions: the outer cortex is lighter coloured, and contains the glomeruli and the beginning and end of each nephron. The inner medulla contains the middle u-shaped part of each nephron (e.g. the loop of Henlé). The medulla extends into the central ‘pelvis’ of the kidney as projections called pyramids.

Kidney in Cross-Section

Kidney Structure

Further Research