Learning IntentionsI can describe the role of the kidneys. I understand and can describe the process of filtration and reabsorption in the nephron.

Success CriteriaI 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 KidneysThe Kidneys

The kidneys have 2 main The kidneys have 2 main functions.functions.

– Maintaining water balance.Maintaining water balance.

– Cleaning of the blood- getting rid Cleaning of the blood- getting rid of poisonous waste substances, of poisonous waste substances, such as such as ureaurea, from the body., from the body.

UreaUrea• Urea is a poisonous Urea is a poisonous

waste product formed waste product formed from amino acids. from amino acids.

• It is made in the liver It is made in the liver and travels to the and travels to the kidneys in the blood kidneys in the blood where it is filtered from where it is filtered from the bloodthe blood

• If not removed its build If not removed its build up causes death!up causes death!

A

F

B

C

D

E

Kidney

ureter

bladder

urethra

Renal artery

Renal vein

The Kidney’s under take two functional The Kidney’s under take two functional processes:processes:

• Filtration of the bloodFiltration of the blood

• Selective re-absorption of useful Selective re-absorption of useful substances e.g. Water, glucose, salts.substances e.g. Water, glucose, salts.

How the Kidneys WorkHow the Kidneys Work

• Each kidney is made up Each kidney is made up of about 1 million tiny of about 1 million tiny filtering units called filtering units called NEPHRONSNEPHRONS which which filterfilter the blood and then the blood and then allow allow reabsorption ofreabsorption of the useful substances the useful substances back into the back into the bloodstream.bloodstream.

 

Bowman’s Capsule

Look at these animations.

How the kidneys workHow the kidneys work

• Blood from the renal artery enters a knot Blood from the renal artery enters a knot of capillaries called the of capillaries called the GLOMERULUSGLOMERULUS..

• The blood is under high pressure and all The blood is under high pressure and all small molecules such as small molecules such as water, salt, water, salt, glucose & ureaglucose & urea are forced out of the blood are forced out of the blood and into the and into the BOWMANS CAPSULE.BOWMANS CAPSULE.

• The filtered small molecules make up The filtered small molecules make up glomerular glomerular filtratefiltrate and passes into the and passes into the nephronnephron..

• Useful substances Useful substances such assuch as glucose, water & salt glucose, water & salt are are reabsorbedreabsorbed into the capillaries from the into the capillaries from the Kidney tubuleKidney tubule..

• The The urea and excess water & salturea and excess water & salt are passed are passed into the into the COLLECTING DUCT.COLLECTING DUCT.

• This is passed along the This is passed along the URETERURETER and stored in and stored in bladder as bladder as URINE.URINE.

• Urine leaves the body via the Urine leaves the body via the URETHRAURETHRA..