Excretion - Removal of metabolic waste, excess substances and toxic materials

Includes - Lungs, Liver, Kidney

Organ	Excretes	Why Toxic
Lungs	Carbon Dioxide [Aerobic Respiration]	Carbon Dioxide - Dissolved in water → Acidic solution → Reduces enzyme activity
Kidneys	Excess water, salts and urea [Breakdown of excess amino acids]	Urea → Toxic
Liver	Ions	Excess

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Urinary System -

Kidney - 2 bean-shaped organs → Filter blood

Ureter - Tube connecting kidney to bladder

Bladder - Stores urine as produced by kidney

Urethra - Tube connecting bladder to exterior

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Kidney -

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Start in cortex, loop into medulla and come back to cortex
The contents of a nephron drains into the inner part of the kidney → urine collects there → ureter → bladder