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Main Functions of the Urinary System

​Main Functions of the Urinary System: 

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1. EXCRETION: To rid the body of metabolic waste which is toxic to our blood (urea, uric acid, creatinine).

2. OSMOLARITY: To maintain normal water-salt balance.

3. ACIDITY: To maintain acid-base level n the blood (pH).
 

Main Organs that Excrete Waste:

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  • SKIN: Has sweat glands that remove urea and salts through sweat.

  • LIVER: Creates urea and detoxifies the blood.

  • LUNGS: Removes CO2 and H+ ions as we breathe

  • KIDNEYS: Removes uric acid, excess salts, water, and poisonous substances through urine.

Excretion Vs Elimination

Excretion:

  • The removal of waste produced by cell from metabolism like urine, sweat, carbon dioxide, etc. 

    • Urine contains salts, ions, urea and 95% water

    • Our bladder can hold 400 to 600 mL of urine before it has to be removed. 

    • Amino acids break down into ammonia in the liver which is then combined with carbon dioxide to form urea.

Elimination:

  • The removal of waste produced during digestion like fecal waste (ie. poop)

Main Component of the Urinary System

The Kidney:

  • Humans have a pair of kidneys

    • Each kidney is a bean-shaped, 10 cm long organ ​that is supplied with blood by the renal artery and blood is taken away by the renal vein.

  • Kidneys receive about 20% blood flow and only make up 1% of our body weight

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  • Urine exits the kidney through a duct called the URETER

    • The ureter drains into the URINARY BLADDER

    • Once the bladder is full, urine is expelled through the URETHRA

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  • The function of the kidney is to maintain osmoregularity (a water-salt balance) and regulate the composition of blood.

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TERMS:

KIDNEY: filters blood and removes waste from the body

URETER: carries urine from the kidney to the bladder

BLADDER: stores urine until it can be expelled 

URETHRA: takes urine from the bladder to the outside of the body

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