Learning Intentions  I can describe the role of the kidneys.  I understand and can describe the process of filtration and reabsorption in the nephron. Success Criteria I can label a diagram of the urinary system. I can name the parts of the kidney nephron. I can describe the process of filtration and reabsorption.

The Kidneys The kidneys have 2 main functions. –Maintaining water balance. –Cleaning of the blood- getting rid of poisonous waste substances, such as urea, from the body.

Urea Urea is a poisonous waste product formed from amino acids.Urea is a poisonous waste product formed from amino acids. It is made in the liver and travels to the kidneys in the blood where it is filtered from the bloodIt is made in the liver and travels to the kidneys in the blood where it is filtered from the blood If not removed its build up causes death!If not removed its build up causes death!

A F B C D E Kidney ureter bladder urethra Renal artery Renal vein

The Kidney’s under take two functional processes: Filtration of the bloodFiltration of the blood Selective re-absorption of useful substances e.g. Water, glucose, salts.Selective re-absorption of useful substances e.g. Water, glucose, salts.

How the Kidneys Work Each kidney is made up of about 1 million tiny filtering units called NEPHRONS which filter the blood and then allow reabsorption of the useful substances back into the bloodstream.Each kidney is made up of about 1 million tiny filtering units called NEPHRONS which filter the blood and then allow reabsorption of the useful substances back into the bloodstream.

Bowman’s Capsule Look at these animations.

How the kidneys work Blood from the renal artery enters a knot of capillaries called the GLOMERULUS.Blood from the renal artery enters a knot of capillaries called the GLOMERULUS. The blood is under high pressure and all small molecules such as water, salt, glucose & urea are forced out of the blood and into the BOWMANS CAPSULE.The blood is under high pressure and all small molecules such as water, salt, glucose & urea are forced out of the blood and into the BOWMANS CAPSULE.

The filtered small molecules make up glomerular filtrate and passes into the nephron.The filtered small molecules make up glomerular filtrate and passes into the nephron. Useful substances such as glucose, water & salt are reabsorbed into the capillaries from the Kidney tubule.Useful substances such as glucose, water & salt are reabsorbed into the capillaries from the Kidney tubule. The urea and excess water & salt are passed into the COLLECTING DUCT.The urea and excess water & salt are passed into the COLLECTING DUCT. This is passed along the URETER and stored in bladder as URINE.This is passed along the URETER and stored in bladder as URINE. Urine leaves the body via the URETHRA.Urine leaves the body via the URETHRA.