Transcript Urinary System

• Excretion is needed in order to achieve
homeostasis- the balance of everything
in the body
The Urinary System
Urinary System
• 2 wastes that need to be excreted:
–Urea
–Uric Acid
• These wastes are
–nitrogenous (contain nitrogen)
and
–poisonous (can kill us if not excreted)
How are they produced?
• By the metabolism (break down) of protein in cells
• Amino acids + O2 
heal and grow + H2O + urea and uric
acid
Good
Poisonous
• Urea and uric acid is produced
in the cells
• It circulates in the blood
• The blood is brought to the
kidneys to be filtered
How System Works - Parts
• 2 kidneys
– Function:
• filter blood (125 mL of blood
per minute)
• produce urine
• Produce a hormone called renin (causes
thirst)
How System Works - Parts
• Kidneys are filled with capillaries called
NEPHRONS, which are responsible for filtering
blood.
• It decides what we urinate out and what we
keep.
How System Works - Parts
• How do kidneys filter?
– Decide if there is enough water, vitamins and
minerals in system.
– Keeps what it needs, eliminates what it doesn’t
How System Works - Parts
• Ureters
–Tubes that collect urine from
kidneys and bring it to the bladder
How System Works - Parts
• Bladder
• Expandable bag that stores urine.
Has a sphincter muscle that closes
and opens.
How System Works - Parts
• Urethra
–Tube that urine comes out of.
–Male: long
–Female: short  more bacteria and
more urinary tract infections
How System Works - Parts
• Renal Artery
– Carries unfiltered, oxygenated
blood away from heart to kidneys.
– Carries O2, nutrients, blood
components, minerals,
vitamins, water, urea and
uric acid
How System Works - Parts
• Renal vein
–Carries filtered deoxygenated
blood back to heart
–Carries same contents as
above, but urea and uric
acid have been removed
• Urine
– Excess water, vitamins, minerals
– Urea and uric acid
– Dead hemoglobin, which makes urine yellow