4BI1
Excretion
Structures and Functions in Living Organisms · 6 question types
Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 12% of your exam marks.
stable
High
Stable12%
The kidney and urea production appear regularly; dialysis is a common application question.
The kidneys are part of the urinary system, which filters the blood and removes water-soluble waste in the form of urine. The complete system has five named parts:
| Structure | What it does |
|---|---|
| Kidneys (one pair) | Filter the blood and form urine. Located on either side of the spine, towards the back of the abdomen, just below the ribs |
| Renal artery | Brings blood from the aorta into each kidney to be filtered. The renal artery has a high oxygen and a high urea content |
| Renal vein | Carries filtered blood away from each kidney back to the vena cava. The renal vein has a low urea content |
| Ureter (one per kidney) | The tube that carries urine from the kidney down to the bladder |
| Bladder | A muscular elastic bag that stores urine until it can be passed |
| Urethra | The single tube that carries urine from the bladder out of the body |
A tip for telling the two tubes apart: the ureter is one of two tubes that goes between upper organ (kidney) and bladder, while the urethra is the single tube that ends at the thigh.
