Contents
Key Stage 3
A drawing of a kidney.
Meaning
Kidneys are organs in the excretory system that removes urea and excess water from the blood.
About the Kidneys
Key Stage 4
Meaning
Kidneys are organs in the excretory system that removes urea and excess water from the blood.
About the Kidneys
- The kidneys are responsible for osmoregulation as well as the removal of urea from the blood.
- As blood passes through the kidneys water, urea, glucose and salts diffuse from capillaries into the kidney tubules at in a structure called a nephron. Glucose is completely reabsorbed into the blood while water is selectively reabsorbed depending on the water concentration in the blood.
- The selective re-absorption of water is affected by anti-diuretic hormone. When the levels of anti-diuretic hormone are high most of the water is reabsorbed into the blood. When the levels of anti-diuretic hormone are low the water is not re-absorbed and is passed down the ureters to the bladder.