Excretion

removal of waste products made by cells

Found in plants
Gets rid of oxygen

Found in animals
Gets rid of CO2

Found in animals
Gets rid of urea

Found in animals
Gets rid of water

Removes urea from the blood
Adjust salt levels in the blood
Adjusts water content in the blood (osmoregulation)

Carries urine from kidney to bladder

Stores urine

Holds urine in bladder

Carries urine out of the body

Renal artery carries blood into kidney
Renal vein carries blood out of the kidney
Outer layer called cortex
Middle layer called medulla
Inner layer called renal pelvis

Blood from renal artery flows through the glomerulus - a bundle of capillaries at the start of the nephron
A high pressure is built up which squeezes water, urea, ions and glucose out of the blood and into the Bowman's Capsule
Big molecules like proteins and blood cells are not squeezed out and stay in the blood

As the filtrate flows along the nephron, useful substances are selectively reabsorped back into the blood
All the glucose is reabsorbed from the proximal convoluted tubule so it can be used in respiration by active transport
Sufficient ions are reabsorbed
Sufficient water is reabsorbed from the collecting duct back into the blood by osmosis

Bowman's capsule
Proximal convoluted tubule
loop of Henle
distal convoluted tubule
collecting duct

chemicals that make you produce more urine
eg caffeine and alcohol

Hypothalamus detects low water potential and sends impulse to pituitary gland
Pituitary gland releases more ADH
ADH travels to kidney in the blood
More ADH makes collecting duct walls more permeable
More water is reabsorbed into the blood
Less urine and it is more concentrated

Contains water, urea and ions